Screening for Depression in cADiovasCular pAtients at a Tertiary Center in Trinidad.
Conditions: Depression
Sponsor: The University of The West Indies

SCREENING OF DEPRESSION IN PATIENTS WITH 
CARDIOVASCULAR DISEASE IN A TERTIARY CENTRE IN 
TRINIDAD AND TOBAGO: 
DEPRESS CVD TNT STUDY 
 
Authors: 
1 Naveen Anand Seecheran, MBBS, MSc, FACC, FESC 
1 Cathy-Lee Jagdeo, BSc, MBBS 
 
 
1 Department of Clinical Medical Sciences 
Faculty of Medical Sciences 
The University of the West Indies 
St. Augustine Campus 
 
 
 
20th February, 2019 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

	  
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TABLE OF CONTENTS 
 
 
 
 
 
 
 
Page  
 
ABSTRACT  
 
 
 
 
 
2 
 
 
 
 
 
 
ACKNOWLEDGEMENTS  
 
 
 
3 
 
INTRODUCTION 
 
 
 
 
 
4 
 
METHODS 
 
 
 
 
 
 
14 
 
RESULTS 
 
 
 
 
 
 
21 
 
DISCUSSION  
 
 
 
 
 
33 
 
CONCLUSION 
 
 
 
 
 
47 
 
REFERENCES 
 
 
 
 
 
48 
 
 
 
 
 
 
 
 
 

	  
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ABSTRACT  
 
Objectives: This was an observational study aimed to screen patients with 
cardiovascular disease for depression in Trinidad and Tobago in a tertiary 
centre and to determine if there is a significant association between patients 
with symptoms of depression and other comorbidities. 
Methods: Patients (N=1203) were randomly selected from the outpatient 
cardiology clinics at the Eric Williams Medical Sciences Complex. After 
fulfilling the inclusion criteria and informed consent were obtained, they were 
given the case report form which included the Patient Health Questionnaire 9. 
Results: The study had a 96% respondent rate whereby the average age was 
found to be 62 years old. 47.5% were male and 52.5% were female. 90.2% of 
the sample had cardiovascular disease. 25% of the sample had a PHQ score or 
greater than or equal to 10 with 19.3% having no symptoms of depression. 
Females were found to be more depressed than males (p < 0.001) and only 
ticagrelor use was found to be significantly associated with depression (p 
0.001). Comorbidities associated with depression included hypertension, 
stroke, chronic obstructive pulmonary disease and chronic kidney disease 
excluding diabetes mellitus. 
Conclusion: Approximately one in four patients with cardiovascular disease 
have significant symptoms of depression. Significant associations were found 
between depression and other illnesses. Thus, it is evident that screening for 
depression should be encouraged among patients with cardiovascular disease 
so that patients can be treated optimally and effectively to obtain the best 
outcomes. Further studies are needed to support these findings.  
Keywords: cardiovascular disease; depression; comorbidities. 
 
 
 
 

	  
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ACKNOWLEDGEMENTS 
 
The willingness to participate in the study from the patients of the 
cardiovascular outpatient clinics was immensely appreciated. The research 
study was approved by the Research Ethics Committee of the University of 
the West Indies, St. Augustine and additionally, by the North Central Regional 
Health Authority. The assistance and approval from the Public Health 
Observatories at Eric Williams Medical Sciences Complex allowed the 
investigators of the study to use the facility as a research site which assisted in 
obtaining a large pool of patients with cardiac disease amongst Trinidad. The 
patients and the doctors of the cardiology outpatient clinics at Eric Williams 
Medical Sciences Complex were additionally of great assistance to conduct 
this study as these patients were all part of the clinic listings on each particular 
day. The staff of the cardiology outpatient clinics were very accommodating 
and provided a comfortable environment for the participants of the study. 
 
No funding or sponsorship was obtained for this study and no conflict of 
interest was declared. 
 
 
 
 
 
 
 
 
 
 
 
 

	  
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INTRODUCTION   
  
Coronary artery disease, as well as depression, are both highly prevalent 
diseases. Both of them cause a significant decrease in quality of life for the 
patient and impose a significant economic burden on society(1). The evidence 
is growing that depression per se is an independent risk factor to suffer a 
cardiac event and thus if physicians become more aware of the prevalence of 
depression, this can impact on treating the condition and overall reduce the 
rate of morbidity/mortality in these patients. 
  
Depression is highly prevalent in cardiac patients. Approximately 31-45% of 
patients with cardiac disease which include, coronary artery disease, suffer 
from clinically significant depression with 15-20% of patients with coronary 
artery disease meeting the criteria for major depressive disorder(2). 
Additionally, depression was found to be` more prevalent among females(3). 
Some cardiovascular diseases, such as atrial fibrillation, heart failure and 
patients who are awaiting implantation of implantable cardioverter-
defibrillator devices have been noted to have increased risk for depression and 
major depressive disorder(2). It has also been observed that patients with 
cardiovascular disease have also been found to have other psychiatric illnesses 
such as generalized anxiety disorders, major depressive disorders and post-
traumatic stress disorders(2).  
 
Of significance, 25-45% of patients in Trinidad and Tobago with organic 
diseases have been noted to have features of depression(4). Suicides rates have 
been as high as 12.3/100 000 in Trinidad and Tobago(4). In 2008, 58% of 
males in Trinidad and Tobago died premature deaths as a result of 
cardiovascular disease while 69% of females died premature deaths as a result 
of cardiovascular disease which were between the ages of 30 years old to 69 
years old(5). Therefore, we see that independently, the incidence of depression 
and cardiovascular disease in Trinidad and Tobago is considered to be 

	  
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remarkable. It was additionally observed that 40% of hospitalized patients 
with existing cardiovascular disease had clinical depression in a public health 
institution in Trinidad in one study previously done(6). In this study, patients 
were screened for depression using the patient health questionnaire.  
 
Comparatively, in another study, using the Centre for Epidemiologic Studies 
Depression scale done in Trinidad, it was found that 47% of patients with self-
reported cardiovascular disease had depressive symptoms while 37% of 
patients with depressive symptoms have no self-reported cardiovascular 
disease(7). 
One may question, what is the actual cause of depression; after much research, 
a myriad of hypotheses and theories have been postulated such as genetic and 
psychosocial stress related, stress hormone and cytokine-related, monoamine 
related, the neurotrophic hypothesis of depression, circadian rhythm related to 
altered glutamatergic and gabaergic neurotransmitter related(8). Thus, based 
on supporting and non supporting data for the above, depression is considered 
an etiologically heterogeneous disorder(8). 
 
In comparison, the pathophysiology of cardiovascular disease ranging from 
acute coronary syndromes, heart failure to cardiac arrhythmia disorders, for 
the most is well understood. Data have suggested a causative relationship 
between depression and cardiovascular disease. One such culprit as a common 
finding to be the initiator of both diseases is inflammation(9). Inflammation 
has been shown to be abnormal with some consistency in mood disorders, 
however, cannot account for the entirety of the link between the two disease 
processes(9). 
 
Depression is considered to be a risk factor for developing cardiovascular 
disease as it has biological effects, including abnormalities of endothelial 
function, atherosclerotic plaque integrity and changes in thrombosis or 
hemostasis as well as electrophysiological effects(10). The American Heart 
Association recommends that depression should be recognized as a risk factor 
for coronary heart disease just as hypertension, hyperlipidemia and diabetes 
mellitus(11). There is an 80% risk in developing worsening cardiovascular 

	  
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disease and in addition to an increased mortality rate in adults with depression 
with or without previously existing cardiac disease (11). Based on a number of 
studies, there has not been any clear objective evidence to suggest a causative 
effect of depression on cardiovascular disease, as one is a mind related illness 
and the latter is a somatic disease, making it far more complex in reality to 
understand(12).  
 
Depression has been shown to have a negative impact on patients with 
cardiovascular disease with respect to lifestyle, treatment and compliance(11). 
Thus, even though there is no objective evidence for a causative relationship 
between depression and cardiovascular disease, without a doubt, depression 
plays a major role in fitting the risk factor profile for cardiac disease. 
Additionally, depression is associated with a reduced quality of life and 
worsens the prognosis of cardiovascular disease(13). 
 
This then leads to the next matter to discuss. How would treating depression 
impact on cardiovascular disease and mortality and vice versa? It is unknown 
whether successful treatment of depression impact on reducing cardiac 
morbidity and mortality based on some studies(14) (15). Additionally, 
antidepressants especially SSRI therapy and cognitive behavioural therapy 
have been found to be safe to use in patients with cardiovascular disease(14). 
Treating the symptoms of depression in the cardiac group of patients can aid 
in encouraging compliance with medications(1) and accurate and timely 
assessment of depression in patients with chronic heart disease has the 
potential to influence prognosis and reduce suffering in those who have been 
discharged after hospitalization for cardiac issues(16).  
 
Hence, when depressive symptoms are treated successfully, there is a 
reduction of cardiac mortality and morbidity due to improvement in 
compliance with medication therapy and treatment strategies(15). From the 
Enhancing Recovery in Coronary Heart Disease Study (ENRICHD study), 
treating patients with depression with cognitive behavioural therapy reduced 
mortality and recurrent myocardial infarction, but there was no evidence to 
support a reduction in general cardiac morbidity and mortality outcomes(17). 

	  
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In this study, the cohort was 2481 patients. With respect to the 
pharmacotherapy of depression, a potential side effect of tricyclic 
antidepressant therapy can cause lengthening of the cardiac myocyte action 
potential, less so for tricyclics and SSRI class of antidepressant medications. 
The potential risk of this can lead to precipitating cardiac arrhythmias(18) 
(19). However, in a 5 year follow up study, there was no increased risk for 
cardiac arrhythmias associated with antidepressant class; this risk was 
increased in the first 28 days when using tricyclic antidepressants while 
fluoxetine use did not reveal this finding and there was a significantly lower 
risk associated with its use for cardiac arrhythmias(20). 
 
Due to SSRI medications being safer than other classes of antidepressants in 
patients with cardiac diseases, they are usually effective and the antidepressant 
of choice in a setting of cardiac disease(18). Particular precautions should be 
taken in treating patients with cardiac failure with antidepressants especially in 
those with prolonged myocyte action potentials(18). On the contrary, beta 
blockers particularly propranolol and atenolol along with calcium channel 
blockers can potentially cause depressive symptoms and are drugs used to 
treat cardiac disease(21). 
 
It has been known that low socioeconomic status is a determinant for health 
and more specifically cardiac disease. Those with poor social support have an 
increased risk for cardiovascular disease(22). Similarly, low socioeconomic 
status has also been associated with a higher prevalence of depression(23). 
Using income and education level as a measure of the socioeconomic index, it 
was found that the index can be used to predict depressive symptoms(23). 
Thus, it can be seen that a lower socioeconomic status can imply a higher risk 
for cardiac disease and depression. 
 
Age is noted to be an independent risk factor for the development of 
cardiovascular disease(24). Increasing age has generally been associated with 
a higher risk for developing cardiac disease possibly as there is an increased 
risk for traditional risk factors such as diabetes mellitus and hypertension with 
increasing age(25). 

	  
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It has been hypothesised that a similar relationship exists for increasing age 
associated with depression, however, this has not yet been confirmed 
statistically(26). Thus, increasing age does play a role in the two diseases; but 
confounding variables such as socioeconomic status, in such populations, 
should be taken into consideration. 
 
Interestingly, it has also been suggested that lower education levels are not 
associated with an increase in the incidence of cardiovascular disease in a 
study done among 20 543 Japanese women over a 12 year period(27). In 
another study done in a group of women, there was also an association 
between lower education levels being associated with a higher morbidity and 
mortality rate amongst females with cardiac disease(28). Some literature 
suggests that the link between low education levels and depression is not that 
clear as this relationship is deemed as inconclusive(29). Whilst, in other 
articles, reviewed it was suggested that lower levels of education increase the 
risk for depression and major depressive disorder(30). Therefore, there is 
some element with low education attainment increasing the risk of both 
depression and cardiac disease and this factor should not be ignored. 
 
South Asian ethnicities have a higher risk of cardiac disease, specifically, 
ischemic heart disease whilst African Caribbeans have a lower risk of 
ischemic heart disease(31). However, black Americans have an increased risk 
of cardiovascular disease(32). Internationally, it has been noted that the 
prevalence of depression is more common amongst white Americans and 
Mexican Americans in the United States of America(33). In Trinidad, it was 
found that double the number of Indo-Trinidadians are depressed compared to 
Afro-Trinidadians(34). Ethnicities/racial groups do have a significant 
influence on the disease process involved in cardiac disease and depression 
and should always be taken into consideration. 
Comorbidities most commonly associated in patients with depression include 
acute coronary syndrome, cancers and stroke(35). This may negatively impact 
on the disease processes and depression should be treated, as most times there 
is a deterioration in functionality, while these patients are safely 
monitored(35). The two most commonly reported medical illnesses in 

	  
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association with depression are cardiovascular disease and diabetes 
mellitus(36). Of note, depression is not just associated with other physical 
medical comorbidities but also other mental illnesses such as anxiety 
disorders, alcoholism, obsessive compulsives disorders and personality 
disorders(37). In all, comorbidities other than cardiovascular disease should be 
noted as they can additionally be linked to depressive symptoms. 
 
Approximately 31-45% of patients with coronary artery disease also had 
clinically significant depressive symptoms(2). About 36% of patients with 
heart failure had depressive symptoms while 30-40% undergoing coronary 
artery bypass graft surgery had depressive symptoms(2). Ischemic heart 
disease appears to be the most common type of cardiac disease associated with 
depression. 
 
There are a number of investigational tools and screening questionnaires used 
to assess symptoms of depression such as the Beck’s Depression Inventory, 
Patient Health Questionnaire- 2, Patient Health Questionnaire-9 and the Zung 
depression rating scale to name a few. The Patient Health Questionnaire – 9 
has been shown to have reasonable sensitivity and specificity for patients with 
chronic heart disease(38) and hence is the investigational tool in this study. It 
is noted to be a quick screening test for depression. This questionnaire seems 
to assess any type of mood impairments rapidly and reliably, minimizing 
possible underestimates or misjudgments of the depressive symptomatology 
from both the patients and cardiac unit professionals. It is considered to be the 
gold- standard in the hospital setting(39). 
  
It is recommended that physicians use tools such as the Patient Health 
Questionnaire-9 to screen cardiac patients for depression as there is a link 
between depression and cardiac disease and it is considered to be a 
bidirectional relationship(40). When compared to the Patient Health 
Questionnaire-2, the Patient Health Questionnaire-9 was found to have a 
higher sensitivity and specificity(41). It has been evaluated and shown that the 
Beck’s Depression Inventory II and Patient Health Questionnaires are most 
useful in this setting of assessing patients with cardiac disease for 

	  
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depression(39). In another study where the Patient Health Questionnaire-9 was 
administered as a self-assessment, it was found to have high sensitivity and 
moderate specificity(42). The Patient Health Questionnaire-9 has also proven 
to be useful in resource-poor settings(43).  
 
Other advantages of the Patient Health Questionnaire-9 include that it is a 
quick assessment, it grades the severity of depression, can be obtained in 
different languages, the score is easy to calculate and additionally it can be 
used to reassess patients on antidepressant therapy as it grades depression(44). 
On the other hand, the downside of the Patient Health Questionnaire-9 is that 
it may lead to unnecessary diagnosis of depression and it does not include 
exclusion criteria for other mood disorders in which some patients can be 
misdiagnosed(44).  
 
Based on the above, it can definitely be said that there is a link between 
depression and cardiac disease. But what is the importance of this link or 
relationship? The aim of establishing this relationship in Trinidad amongst a 
large patient population would allow physicians to treat patients optimally and 
be aware of depression being considered a risk factor for cardiac disease. It 
may additionally, help to increase screening for depression in the cardiology 
clinics as if depression is treated appropriately in this cohort of patients, the 
standard of care will without a doubt, improve as controlling and managing 
risk factor of a disease may assist in elimination or reduction of cardiovascular 
disease. This initiative may encourage patients to become more compliant 
with therapy and have a reduction in the morbidity and mortality rates 
associated with cardiac disease in Trinidad. It will also assist this group of 
patients to practise autonomy when it comes to their healthcare and has a 
positive impact on their functionality and lives overall. 
  
Thus, it is important to determine the incidence of depression amongst the 
cardiac patients in Trinidad, to not just initiate treatment, but to further 
establish and raise awareness of this bidirectional link between depression and 
cardiac disease. In summary, depression is considered to be an independent 
risk factor for cardiac disease. In addition, other variables such as 

	  
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socioeconomic status, ethnicity, educational level, medications and other 
comorbidities do have an impact on depression as well in this particular group 
of patients.  
 
The Patient Health Questionnaire-9 is a good screening tool that can be used 
not just for detecting depression, but also for grading depression severity and 
aid with determining response to treatment. Hence, its use in this study. It is a 
quick assessment tool where its advantages outweigh its disadvantages and 
some studies have shown it to be an eye-opening self-assessment tool as well. 
Additionally, if patients are found to be depressed using this screening tool, 
they would be referred to a psychiatrist for further evaluation and treatment. 
This would encourage physicians to treat their patients as a whole being and 
not just focus on their cardiovascular health as there are many connections 
such as depression. It would also allow doctors to have a baseline screening 
score from the Patient Health Questionnaire-9 which is easy to redo and 
reassess patients at any point in time on treatment. 
 
There are a number of studies in the pool of literature which show a 
relationship between depression and cardiovascular disease; however, this 
study aims to raise awareness and implement a change amongst the patients in 
Trinidad and Tobago with cardiac disease so that it would encourage and 
assist physicians to provide optimal health care for patients. It is also aimed to 
screen these patients for depression as in the cardiology clinics, depression is 
highly underdiagnosed and undertreated. 
  
  
  
 
 
 
 
 
 

	  
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METHODS  
 
The study design was a cross-sectional descriptive study performed from 
November 2018 to February 2019. It was performed at the Eric Williams 
Medical Sciences Complex, Champ Fleurs, Trinidad. Of note, this is one of 
the major public hospital institutions in Trinidad under the North Central 
Regional Health Authority whereby there is access to a 24-hour Accident and 
Emergency department where routine medical care is accessible. The 
population of Trinidad and Tobago is approximately 1.37 million people(45), 
in which the north-central distribution of the country seeks health care at this 
institution making it an excellent research site for this study. 
The primary objectives of the study were to screen patients for depression in 
those with cardiovascular disease in Trinidad and Tobago and to determine the 
association between patients with depression and other comorbidities. 
 
Patients for the study were recruited from the cardiology outpatient clinics at 
Eric Williams Medical Sciences Complex as this institution has a very strong 
cardiology background. Patients were targeted for participation in the study 
while waiting to see the attached physician to the cardiology clinic. 
Participants were attained at the Eric Williams Medical Sciences Complex 
during the days Monday to Friday where there were ongoing cardiology 
outpatient clinics. Once informed consent was obtained from these patients, a 
questionnaire was administered to these patients in which the primary 
investigator and/or co-investigator was/were present on site. The number of 
participants in this study was 1203 patients. There were no dropped subjects 
from the study nor were there any incomplete questionnaires by any 
participants. The sample size for this study was calculated to be 1159 patients. 
This was calculated using the MGH Biostatistics Calculator(46). The value 
obtained using this calculator was multiplied by 0.1, the attrition rate of the 
study and then subtracted from the original value obtained using the original 
value that was calculated using the MGH Biostatistics Calculator. 
 

	  
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Based on a study done by Huffman, it was estimated that 40% of patients with 
cardiovascular disease also have depression(2). The Type I error rate 5% (α = 
0.05) making the Type II error rate 95% (β = 0.95) with a statistical power of 
90%. Assuming a 10% patient decline and attrition rate and a minimum 
detectable difference of 10%, the estimated sample size was calculated to be 
1159 patients. 
 
Data collection was performed by the researchers of the study along with eight 
specifically trained and oriented medical students. All data collectors in the 
study were supervised by primary investigator and co-investigator of the study 
so that in the event of any adverse events such as acute psychosis or any acute 
cardiology emergencies, patients could have been referred directly to the 
accident and emergency department at Eric Williams Medical Sciences 
Complex where routine medical care could have been executed. Of note, there 
were no adverse outcomes that occurred in the data collection process during 
this study. 
 
Before ethical approval could be obtained, the co-investigator listed in this 
study had to complete a recommended and required ethics course by the 
University of the West Indies, St. Augustine. The ethics course was able to 
educate the researcher on ethical principles such as informed consent, privacy 
and confidentiality and conflicts of interest associated with research and was 
instituted by the Collaborative Institutional Training Initiative (CITI) 
associated with the University of Miami. It comprised 22 compulsory modules 
with 2 elective modules. Completion of this ethics course was confirmed with 
certification from the institution which was forwarded to the University of the 
West Indies, St. Augustine. 
 
Ethical approval was obtained for this study to be performed from the ethics 
committee of the University of the West Indies, St. Augustine. Additionally, 
approval was obtained from the Head of Cardiovascular Department along 
with the Complex Administrator at Eric Williams Medical Sciences Complex. 
Approval was also granted from the Chief Executive Officer and from Public 
Health Observatories at Eric Williams Medical Sciences Complex in order to 

	  
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use the complex as a research site to ensure that patients were safe and that no 
harm was done for the purpose of research. All of the prior mentioned 
approvals were forwarded to the cardiology outpatient clinic staff members. 
 
Additionally, there was an attached consent form which was also approved by 
the ethical committee of the University of the West Indies, St. Augustine. This 
consent form clearly explained to the participants why the research was being 
conducted, the average duration of completing the questionnaire, the benefits 
and any potential risks associated with participation in the study along with 
the assurance that confidentiality will be maintained throughout the entire 
study and that the patient can stop or not complete the questionnaire at any 
point without any facing repercussions. This information was documented on 
the consent form and also explained by the researchers of the study to each 
potential participant. All additional questions from patients were answered 
truthfully regardless of if it would have affected the patient’s decision to 
participate in the study. 
 
Patients were asked to participate in the study as long as they were registered 
patients at Eric Williams Medical Sciences Complex in any of the cardiology 
outpatient clinics. This was confirmed by matching patients with their 
registration numbers on the cardiology outpatient clinic appointment listings. 
These lists are made prior to each cardiology clinic that is scheduled every 
week on Mondays, Tuesdays, Wednesdays, Thursdays and Fridays. The 
inclusion criteria for participation in the study included patients who were 18 
years old and over along with registered patients of the cardiology outpatient 
clinics at Eric Williams Sciences Complex. The exclusion criteria for 
participants included patients less than 18 years old, those who did not give 
informed consent to participate in the study, patients who were not registered 
patients of the cardiology outpatient clinics at Eric Williams Medical Sciences 
Complex along with patients who were acutely unwell requiring hospital 
admission. No particular gender groups were excluded from this study. In 
addition, no ethnic and or racial groups were excluded from the study. 
 

	  
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Patients who fit the inclusion criteria were approached and then given a 
written informed consent form which was approved by the Ethical Committee 
of the University of the West Indies, St Augustine, explaining the purpose of 
the study, the information collected from the participants of the study and 
what will be done with the recorded data as mentioned above. Commercial 
advertisements including the Internet and newspapers were not used to recruit 
patients in this study. Of note, no rewards or incentives were offered to 
encourage participation in the study by subjects nor were there any 
penalization for declining participation in the study. Specifically, patients were 
not offered any monetary payments to encourage their participation in the 
study. Patients were allowed to decide on their own, whether or not they 
wanted to participate in the study. Subjects were able to participate based on 
the fulfilling inclusion criteria and informed consent attained. Of significance, 
there was no sponsorship obtained to conduct this study.       
 
Confidentiality of patients was kept and ensured as no patient names were 
recorded and all data recorded was de-identified. Patients were uniquely 
identified using their clinic registration numbers of the cardiology outpatient 
clinic. By using registration numbers to identify patients, this assisted in 
preventing duplicate collection and entry of data. Additionally, the database 
was only accessible to the primary investigator and the co-investigator of the 
study. The data was stored on a device which was password protected and 
again this password was only available to the primary investigator and co-
investigator of the study. The database was encrypted to ensure the patient’s 
recorded information was safe. 
 
In addition, there is an immense amount of literature on cardiovascular disease 
associated with depression. One of the hallmarks of this study would have 
been to choose the best screening tool for depression in this setting and the 
population of the cardiology outpatient clinics at Eric Williams Medical 
Sciences Complex. The depression screening tool used in the questionnaire of 
this study was the Patient Health Questionnaire-9. It was selected to be used in 
this setting in comparison to other depression screening tools as it is quick 
which would maintain patients’ attention and prevent them from being too 

	  
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preoccupied and missed seeing the physician in the cardiology outpatient 
clinic. Based on the literature, it is one of the better selections for a population 
to be screened where results are quick. This tool also allowed researchers to 
assess the category of depression into mild, moderate and severe. This allowed 
patients who were high risk to be easily identified in the event of any need for 
admission to the hospital facility. 
 
The potential risks associated with asking questions listed in the Patient Health 
Questionnaire-9 were low. These potential risks included psychological 
trauma, feelings of depression and acute psychosis. Participants were 
monitored in the study during the questionnaire by the primary investigator 
and or of the study for any potential risks. If any risks were detected clinically, 
patients had the opportunity to be referred to the 24-hour accident and 
emergency department of the Eric Williams Medical Sciences Complex for 
further evaluation, admission and treatment. Fortunately, during this study, 
there were no occurrences of adverse events and no participants had to be 
referred to the accident and emergency department. 
 
Of importance, no invasive data was collected from participants in this study. 
No blood samples were drawn and no drugs being tested were administered to 
any patients enrolled in the study. Additionally, any patients deemed as 
medical emergencies had the opportunity to be referred to the accident and 
emergency department of Eric Williams Medical Sciences Complex where the 
routine medical protocol was followed and appropriate referrals were made. 
Some examples of these emergencies included acute psychosis, acute coronary 
syndromes and acute heart failure. 
 
The scores of the Patient Health questionnaire-9 were verbally communicated 
to the patients in confidentiality by the primary investigator and or co-
investigator of the study along with the interpretation of the score and what it 
meant on the depression scale. Patients were given the opportunity to decide if 
they wanted these results communicated to the physician seeing them in the 
cardiology outpatient clinic and if so; the results were given to their respective 

	  
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physicians who would have decided on appropriate referrals and routine 
medical care. This would include appropriate referrals to psychiatry. 
 
The Social Sciences 24 (SPSS, Chicago, Illinois USA) was the software used 
for the entry of data and its analysis. Descriptive analyses were performed 
which were unadjusted. Statistical significance was accepted as p < 0.05. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

	  
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RESULTS  
 
Out of 1253 patients being approached to participate in the study, 1203 gave 
informed consent to participate in the study, giving an overall response rate of 
96%. Based on Table 1, the average age of the study population was found to 
be approximately 62 years old with the distribution of the study population 
being 47.5% male and 52.5% female. There were no other genders groups 
such as lesbian, bisexual and gay in the study population. Based on the 
educational background of the study population, the majority of patients has a 
background of up to primary school education of 49.5% while just 6.6% of the 
population has a background of no education. The income levels of these 
patients ranged from 28.2% of patients having no income at all, with 52.5% of 
patients being pensioners who received a pension income. Of note, only 3.1% 
of the population has earnings of more than $10 000.00. The majority of 
patients in the study was of Indo-Caribbean descent making up 57.4% of the 
participants. Afro-Caribbean ethnicities made up approximately 31.5% of the 
participant group. 
 
 
 
 
 
 
 
 
  
 
 
 
 

	  
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Demographics (N=1203) 
Value 
*Age (years) 
62.5 ± 13.1 
  
+Gender 
 Male 
Female 
  
 571 (47.5%) 
632 (52.5%) 
+Education 
 None 
Primary 
Secondary 
Tertiary 
  
 79 (6.6%) 
595 (49.5%) 
400 (33.3%) 
129 (10.7%) 
+Salary 
 None 
Pension 
5000-10 000 
>10 000 
  
 339 (28.2%) 
631 (52.5%) 
196 (16.3%) 
37 (3.1%) 
  
+Ethnicity  
Indo-Caribbean 
Afro-Caribbean 
Mixed/Other 
  
 690 (57.4%) 
379 (1.5%) 
134 (1.1%) 
*Mean ± Standard deviation 
+Frequency (Percentages) 
Table 1: Demographics of Sample  
 
 

	  
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Table 2 illustrates the distribution of diseases of the study population out of 
1203 patients. 90.2% of these patients had coronary artery disease/ 
cardiovascular disease. 9.8% of these patients were registered patients of the 
cardiology outpatient clinics who were referred for suspected cardiac disease 
and had pending cardiac investigations such as coronary angiograms and 
transthoracic echocardiograms. Additionally, many of these patients had 
lifestyle diseases where 47.9% of patients were diabetic and 71.5% of patients 
were hypertensive. Approximately 51.0% of these patients also had 
hyperlipidemia. Only a small percentage of the sample population had COPD 
which was 5.7% of the sample of participants. 
 
Disease (N=1203) 
+Value 
Coronary artery disease/ cardiovascular disease 1085 (90.2%) 
DM 
576 (47.95%) 
HTN 
860 (71.5%) 
Hyperlipidemia 
614 (51.0%) 
COPD 
69 (5.7%) 
Chronic kidney disease 
101 (8.4%) 
Stroke 
139 (11.6%) 
Peripheral vascular disease 
115 (9.6%) 
+Frequency (percentages) 
Table 2: Disease Status of Sample 
 
 
 
 

	  
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With respect to the patients who had symptoms of depression based on the 
Patient Health Questionnaire-9 scores, a PHQ score of 10 or more was used as 
a cut off to represent the percentage of patients with significant symptoms of 
depression. The PHQ more than or equal to 10 has been noted to have a 
specificity and sensitivity of 88% for major depression(47) and hence, why it 
was used as the score for significant depressive symptoms. Figure 1 depicts 
the distribution of the sample population with respect to PHQ scores. A total 
of approximately 25% of patients had a PHQ greater than or equal to 10 
representing severe depressive symptoms. Only a small percentage of 19.3% 
of patients had no symptoms of depression. 
 
 
 
 
 
826 patients were on aspirin therapy. This accounted for 68.7% of the sample 
population while 31.8% of patients were on clopidogrel. Additionally, 53.5% 
of patients were on a statin. 17% of patients were on calcium channel blockers 
as compared to 44.7% of patients were on beta-blocker therapy. Only 
approximately 2.2% of patients were on ticagrelor therapy. 9.3% of patients 
were on warfarin and 1.2% of patients were on Factor Xa inhibitor drugs. The 
distribution of medication use can be seen in Table 3. 
 

	  
23	  
From Table 4, the female population was found to have more depressive 
symptoms than the male population with a p-value of <0.001. Other 
statistically significant findings were that patients with no education or 
secondary level education were found to be depressed and had PHQ scores of 
more than or equal to 10. Very low-income brackets and very high-income 
bracket patients were also found to be more depressed in this sample of 
patients using Fisher’s Exact test. Chi-squared testing revealed no associations 
between depression and ethnicity in this population of patients. 
 
With respect to medication use, the only significant association between 
depression and medication use was found with ticagrelor with a p-value of 
0.001. Out of 304 patients with PHQ greater than or equal to 10, 4.9% were on 
ticagrelor. There were no statistically significant associations found between 
depression and the use of beta blockers, calcium channel blockers, analgesic 
use, ACE inhibitors, ARBs and statins. This can be seen clearly in Table 5. 
 
The number of diseases was positively correlated with having major 
depression with an odds ratio of 1.248 (95% Confidence Interval: 1.125-
1.384) Additionally, the number of drugs was positively correlated with 
having major depression with an odds ratio of 1.062 (95% Confidence 
Interval: 1.005-1.123). 
 
When adjusted for age, gender, ethnicity, salary and education, there were a 
number of diseases associated with depression in this study. Hypertension, 
COPD, chronic kidney disease and stroke were all significantly associated 
with depression. When adjusted, the odds ratio for hyperlipidemia associated 
with depression was 1.263 (95% CI 0.965-1.653), making it not statistically 
significant. 
 
In summary, approximately 25% of the sample population had significant 
symptoms of depression in which their PHQ score was greater than or equal to 
10. Significant association were found with comorbidities such as 
hypertension, COPD, Chronic kidney disease and stroke. Associations were 
also found between depression and the use of ticagrelor. Additionally, the 

	  
24	  
female gender had a tendency to be more depressed, along with low salary 
brackets of income and pensioners being more depressed. 
Drug (N=1203) 
+Value 
Aspirin 
826 (68.7%) 
Clopidogrel 
382 (31.8%) 
ACE inhibitors 
505 (42.0%) 
ARB 
150 (12.5%) 
Beta Blockers 
538 (44.7%) 
Statin 
644 (53.5%) 
Ivabradine  
88 (7.3%) 
Trimetazidine  
313 (26.0%) 
Nitrates 
282 (23.4%) 
Spironolactone 
61 (5.1%) 
Calcium channel blockers 
204 (17.0%) 
Loop diuretics 
211 (17.5%) 
Vitamin K antagonists 
112 (9.3%) 
Factor Xa inhibitors 
14 (1.2%) 
Analgesics 
23 (1.9%) 
Ticagrelor 
27 (2.2%) 
Table 3: Drug Use in Sample 
 
+Frequency (percentages)  
 

	  
25	  
 
 
 
Demographic 
PHQ < 10  (n=899) PHQ ≥ 10  (n=304) p value 
*Age (years) 
mean ± SD 
62.57 ± 13.1 
  
60.88 ± 13.1 
0.052 
+Gender 
  
Male 
Female 
  
  
  
463 (51.5%) 
436 (48.5%) 
  
  
108 (35.5%) 
196 (64.5%) 
  
  
 
< 0.001 
+Education 
  
None 
Primary 
Secondary 
Tertiary 
  
  
  
46 (5.1%) 
432 (48.1%) 
317 (35.3%) 
104 (11.6%) 
  
  
33 (10.9%) 
163 (53.6%) 
83 (27.3%) 
25 (8.2%) 
  
  
0.001 
0.094 
0.011 
0.109 
+Salary 
  
None 
Pensional 
5000 – 10000 
>10 000 
  
  
  
221 (24.6%) 
490 (54.5%) 
154 (17.1%) 
34 (3.8%) 
  
  
118 (38.8%) 
141 (46.4%) 
42 (13.8%) 
3 (1.0%) 
  
  
<0.001 
0.017 
0.208 
0.012 

	  
26	  
Demographic 
PHQ < 10  (n=899) PHQ ≥ 10  (n=304) p value 
~Ethnicity 
  
Indo-Caribbean 
Afro-Caribbean 
Mixed/Other 
  
  
  
510 (56.7%) 
292 (32.5%) 
97 (10.8%) 
  
  
180 (59.2%) 
87 (28.6%) 
37 (12.2%) 
  
  
 
0.426 
 
*Independent Sample t test 
+Fisher’s Exact test 
~Chi Square test 
 Table 4: Association between Demographics and Major Depression 
(PHQ ≥ 10) 
 
 
 
 
 
 
 
 
 
 
 
 
 

	  
27	  
 
 
 
 
Drug 
*PHQ<10 
(n=899) 
*PHQ ≥ 10 
(n=304) 
p 
value 
Aspirin 
  
606 (67.4%) 
220 (72.4%) 
0.116 
Clopidogrel 
  
291 (32.4%) 
91 (29.9%) 
0.476 
ACE inhibitor 
  
363 (40.4%) 
142 (46.7%) 
0.060 
ARB 
  
113 (12.6%) 
37 (12.2%) 
0.920 
Beta blocker 
  
399 (44.4%) 
139 (45.7%) 
0.689 
Statin 
  
473 (52.6%) 
171 (56.2%) 
0.287 
Ivabradine  
  
71 (7.9%) 
17 (5.6%) 
0.204 
Trimetazidine 
 
  
222 (24.7%) 
91 (29.9%) 
0.082 
Nitrates 
  
202 (22.5%) 
80 (26.3%) 
0.183 

	  
28	  
Drug 
*PHQ<10 
(n=899) 
*PHQ ≥ 10 
(n=304) 
p 
value 
Spironolactone 
41 (4.6%) 
20 (6.6%) 
0.174 
Calcium channel 
blocker 
  
149 (16.6%) 
55 (18.1%) 
0.537 
Loop diuretic 
  
151 (16.8%) 
60 (19.7%) 
0.257 
Vitamin K 
antagonists 
  
81 (9.0%) 
31 (10.2%) 
0.568 
Factor Xa inhibitor 
  
11 (1.2%) 
3 (1.0%) 
>0.99 
Analgesics 
  
14 (1.6%) 
9 (3.0%) 
0.145 
Ticagrelor 
  
12 (1.3%) 
15 (4.9%) 
0.001 
*Frequency (percentages) 
Table 5: Association between Medication use and Major Depression 
(PHQ ≥ 10) 
 
 
 
 

	  
29	  
Disease 
(Comorbidity) 
  
Unadjusted Odds Ratio 
(95% CI) 
*Adjusted Odds 
Ratio 
(95% CI) 
HTN 
  
1.821 (1.330-2.492) 
1.988 (1.414-2.797) 
Hyperlipidemia 
  
1.347 (1.037- 1.750) 
1.263 (0.965-1.653) 
COPD 
  
1.741 (1.046-2.897) 
1.703 (1.009-2.876) 
Chronic Kidney 
disease 
  
1.896 (1.239-2.901) 
1.872 (1.207-2.902) 
Stroke 
1.665 (1.142-2.427) 
1.847 (1.251-2.728) 
*Adjusted for Age, Gender, Salary and Education 
 Table 6: Association between Diseases (Comorbidities) and Major 
Depression (PHQ ≥ 10) 
  
 
 
 
 
 
 
 
 
 

	  
30	  
DISCUSSION  
 
In this study, it was found that the mean of ages of the sample population was 
62 years old in which the female patients were more likely to have depressive 
symptoms as compared to the males. This was not surprising as it has been 
found that depression is 1.7-fold greater incidence in women(48). This gender 
disparity has well been documented in the literature that the female gender is 
associated with a higher prevalence of depression(49). In another study 
supporting this finding, it was found that women are twice as likely to develop 
depression in their lifetime than men(49). Some postulated causes for this 
gender gap for depression emerge from biological sex differences and have 
less to do with other issues such as cultural differences, education and 
diet(48). In this study, 64.5% of females had depression symptoms determined 
by a PHQ score or greater than or equal to 10. The female and male 
distribution of the sample population in this study was approximately evenly 
distributed where about 52.5% were females.  Additionally, another article 
suggested that women tend to have internalizing features of depression 
whereas men external features of depression(48). 
 
Out of 1203 patients, more than 50% of the population had only up to primary 
level education. 10.9% of the population had no formal education was found 
to have significant symptoms of depression. Lower levels of educational 
attainment are associated with a higher rate of depression in the western 
world(50). From this evaluation, the association was not due to genetic effects 
but more environmental factors such as socioeconomic factors(50). 
The HUNT study found that there was a protective effect of higher levels of 
educational attainment associated with a lower risk for depression and anxiety; 
seeming to have a cumulative effect throughout life(29). Some proposed 
hypotheses for this protective effect include higher education level attainment 
aid in more satisfactory occupations with higher salaries, healthier lifestyle 
practices and better development of self-efficacy resulting in enhanced coping 
mechanisms with stressors associated with life(51). In China, it was found that 
lower levels of education were associated with a lower socioeconomic status 
which led to an increased likelihood for the development of major depressive 

	  
31	  
disorder in a female population that was studied(52). Consistent with the 
findings of this study, there was a positive correlation between lower levels of 
education and mental health in general in which the relationships were 
strongly related to employment and being in a relationship(53). Therefore, it 
can be seen that the relationship between low education levels and depression 
has been established throughout the western and eastern continents. 
 
Patients that were found to have significant symptoms of depression (PHQ 
greater than or equal to 10) were found to have no salary earnings, 
pensionable earnings or those in the greater than $10 000.00 salary bracket. In 
one meta-analysis done, it has been shown that depression is more prevalent in 
populations where there is a greater degree of income inequality(54). Another 
study also supported this finding was assessed using the European Social 
Survey 2006/2007 in which it was found that income inequality was 
associated with higher rates of depression(55). In assessing depression using 
the General Health Questionnaire, it was similarly found that 20-30% of 
people with depression were in the lowest income or wealth categories as 
compared to 10-15% were in the higher income brackets(56). Hence, 
demonstrating depression in the lowest and highest income brackets as found 
in this study. Family or household income seems to have some protective 
effect against depression as proposed in another study(57). Hypothesized 
theories to support these finding include two main theories of social causation 
and social selection(58). Depression may cause stress, reduced coping 
mechanisms and adversity which may be the aetiology of low-income settings 
and increased risk for the development of mental illness as proposed by the 
social causation theory(58). The social selection hypothesis that those with 
mental illness are more likely to have a reduction in socioeconomic status as a 
result of possible genetic factors, increased incidence of hospitalizations and 
increased rates of unemployment(58). On the contrary, it was also found that 
depression was more prevalent amongst those with higher income earnings 
compared to those with lower incomes in a meta-analysis and systematic 
review which included 26 studies(54). Those earning more than $10 000.00 
was found to have more significant symptoms of depression which was a 
statistically significant finding in this study. 

	  
32	  
 
There were no significant associations between any particular ethnic group 
and depression found in this study. In comparison. In another study which 
compared Whites, Hispanics and African Americans, it was found that 
depression was more prevalent among the minority groups (Hispanics and 
African American)(59). Possible explanations for these findings were that the 
minority groups were more likely to be female, lived alone, had one living 
parent and had more chronic diseases(59). The ethnic distribution of the 
patient population in this study was quite different. Likewise, there were 
higher rates of depression amongst African Americans and Mexicans with 
significant lower depression care use(60). Physical health among ethnic 
groups was another variable which impacted upon the rates of depression 
amongst different ethnic groups as it was found in England that South Asians 
were more depressed than Whites as a result of poorer physical health 
status(61). Of significance, it has been reported that foreign-born ethnicities 
have lower rates of depression when compared to non-foreign-born ethnicities 
in the United States of America(62). In another local study assessing 
hospitalized patients with cardiac disease for depression, no particular ethnic 
group was significantly more depressed as depicted in this study(6). Of note, 
there is a paucity of local data comparing Caribbean ethnicities and their 
association with the prevalence of depression. 
 
90% of 1203 respondents were reported as having coronary artery disease/ 
cardiovascular disease in the sample population. However, the remaining 10% 
of patients were still registered patients of the cardiology outpatient clinics at 
Eric Williams Medical Sciences complex with no confirmed cardiac diagnosis 
at this point of evaluation. This could occur as a result that there was no 
confirmed or objective evidence thus far, to confirm the presence of cardiac 
disease in these particular patients. For instance, some of these patients would 
have cardiac type symptoms and referred to a specialist cardiology clinic to be 
investigated for a disease process and thus, would be awaiting their 
investigations and results. Additionally, as it was an outpatient setting some of 
the results of investigations such as coronary angiograms, transthoracic 
echocardiography reports, physiological exercise stress test reports would still 

	  
33	  
be pending in which patients would routinely be seen while awaiting these 
investigations or results by their physicians to ensure no change or worsening 
in their symptomatology and to ensure no new symptoms arising for further 
evaluation and investigation. They were still included in the sample as they are 
registered patients of the cardiology clinics and they would have had 
symptoms to represent cardiac disease clinically at some point in their 
presentation. 
 
Depression symptoms were prevalent in other disease conditions in this study. 
These included hypertension, chronic obstructive lung disease, chronic kidney 
disease and stroke after being adjusted for age, gender, salary and education 
levels. After the odds ratio was adjusted for age, gender, salary and education, 
hyperlipidemia was not significantly associated with depression. It was found 
that both diseases, depression and hypertension can impact on each other(63). 
Hence, patients who were depressed were found to have poorly controlled 
hypertension while patients with hypertension were found to have 
depression(63). The prevalence of depression in patients with hypertension 
was found to be 26.8%(64). Similarly, depression is common in patients with 
COPD. The prevalence of depression in COPD has been found to be 
approximately 40% which is much higher than those with hypertension(65). 
The relationship between COPD and depression also seems to be bidirectional 
and nicotine dependence associated with COPD seems to have a major impact 
on this occurrence(66). Likewise, there is a  relationship between patients who 
suffered a stroke and depression. Depression was found to be 1.77 times more 
common in those patients with a previous stroke and linked to social distress 
after suffering a stroke(67). Patients with chronic kidney disease have also 
been found to have varying levels of depression(68). There have been studies 
which reported that patients with chronic kidney disease who have depression 
are undertreated(69). 
 
Out of all the medication associations with respect to depression, the only 
ticagrelor had a statistically significant relationship with significant symptoms 
of depression. The drug ticagrelor is an antiplatelet, a direct-acting inhibitor of 
adenosine diphosphate receptor P2Y12(70). Conduction abnormalities have 

	  
34	  
been reported after an acute coronary event with the use of ticagrelor in a case 
reported in 2017(71) which been well documented in the literature. In the 
PLATO trial, out of 9235 patients, approximately 1.1% of patients 
experienced depression with ticagrelor(70). When compared to clopidogrel, 
the rate of depression was quite similar(70). Thus far, there have not been any 
major findings of depression associated with the use of ticagrelor as found in 
this study. 4.9% of patients had a PHQ of more than or equal to ten, who were 
taking ticagrelor. This finding may have been related to depression being 
associated with the disease that ticagrelor was being used to treat, coronary 
artery disease. 
The categories of depression were divided into no depression, minimal 
depression, mild depression, moderate depression, moderately severe 
depression and severe depression based on the Patient Health Questionnaire-9 
score. Patients with significant symptoms of depression were defined as a 
patient who had a PHQ-9 score of greater than or equal to ten. This cut off was 
used as it has been documented in the literature to have a sensitivity and 
specificity of 88% for detecting major depressive disorder(47). The PHQ-9 
scores greater than or equal to ten would include the categories of moderate 
depression, moderately severe depression and severe depression. In this study, 
it was found that approximately 25% out of 1203 patients had significant 
symptoms of depression while only 19.3% of this population had no 
symptoms of depression. Approximately, 31-45% of patients with cardiac 
disease have been reported to be depressive symptoms(2). It can be clearly 
demonstrated that depression is without a doubt, underdiagnosed in the 
outpatient cardiology clinics at the Eric Williams Medical Sciences Complex. 
It should be noted that in this setting, the Patient Health Questionnaire - 9 was 
not used as a diagnostic tool but as a screening tool for depression as it has 
been well documented in the literature and has been shown to work very well 
for screening a population for depression(72). Additionally, it has 
demonstrated great use in determining the severity of depression(47). The 
phrase “ depression” in this study was used to represent the risk for major 
depression or likelihood for meeting the criteria for the diagnosis of 
depression. 
 

	  
35	  
Of importance, out of 1203 respondents, no patients were previously 
diagnosed or gave a medical history of a formal diagnosis of depression even 
though approximately 25% of this population had significant symptoms of 
depression. Two patients were on fluoxetine therapy and alprazolam therapy 
for generalized anxiety disorder. In a population with cardiac type diseases, 
the prevalence of depression is three-fold higher than that of the general 
population and thus, has been well documented to be underdiagnosed in these 
patients(11), even though it has been reported as a risk factor for developing 
cardiac disease(11). Those who have depression with cardiac disease have a 
worse outcome than those who are not depressed(18). This finding may be 
supported as patients who are depressed are likely to be non-compliant with 
therapy for their cardiac condition(18). Thus, it is extremely important to 
screen this population of patients to reduce the rates of morbidity and 
mortality. It is recommended that patients with cardiac disease should be 
screened for depression so that the condition is not underrecognized and 
undertreated in an effort to improve the overall outcome of such patients. 
However, there are no studies which have shown that community-based 
screening for depression improves cardiovascular outcomes(73).  
 
As previously mentioned, ticagrelor was the only drug from the study which 
was linked to patients demonstrating significant depressive symptoms. It is 
important to note that a pertinent negative finding from the study was that 
patients on beta-blocker therapy did not exhibit any significant symptoms of 
depression and this finding is supported in the literature. It was found that 
there was an only small risk of fatigue and sexual dysfunction associated with 
beta blockers but there was no increased risk for depression in using these 
drugs(74). Calcium channel blockers are common drugs using in the treatment 
of hypertension, a risk factor for cardiac disease and also depression. 
Interestingly, there is some degree of controversy with respect to if calcium 
channel blocker therapy is linked to depression and increased suicidal rates. In 
an observational Swedish study, there was a significant correlation between 
the use of calcium channel blockers and increase the chance of suicide after 
being adjusted for age and sex(75). In this study, that correlation was not 
found between the use of calcium channel blockers and depression. Another 

	  
36	  
class of drug used in the treatment of coronary artery disease includes statins. 
In this study, there was no correlation between statin therapy and depression. 
However, in a Swedish cohort, it was found that statins, specifically 
simvastatin, may have some protective effect against depression, especially in 
patients over the age of 40 years old(76). 
 
Unexpectedly, there was no association found between patients with diabetes 
mellitus and significant symptoms of depression even though some literature 
has supported this association. In another local study done in 2013, it was 
found that depression was significant among patients with diabetes mellitus, 
hypertension and those with heart disease(77). This association linking 
depression and diabetes mellitus was also found when studied in patients from 
Malaysia, where patients were found to be depressed likey as a result of 
diabetic complications(78). In the Madrid Diabetes Study, patients with type 2 
diabetes were also found to have depression most likely as a result of their 
health status, mental status, diabetic complications and gender(79).  One 
studied aetiology for this association of depression and diabetes mellitus may 
be linked to the use of insulin therapy as it was found that patients on insulin 
therapy had a higher risk of depressive symptoms(80). The importance of 
these associations between depression are other comorbidities lie in the fact 
that poorly controlled depression, poorly controlled diabetes mellitus and 
other poorly controlled diseases are linked to worse outcomes and result in an 
overall greater health care cost(81). Thus, the importance to observe these 
associations and aim to treat these diseases and not fail to notice symptoms of 
depression among this group of patients and it does have an impact on 
morbidity and mortality rates. 
 
One assessment done using the Patient Health Questionnaire - 9 was 
functionality status. It is imperative to include this aspect of the assessment as 
it was found that the severity of depression increased, there was a decline in 
the functional status of individuals(47). The severity of depression is 
additionally essential to determine as individuals with more severe depression 
do worse(82). In another study which evaluated patients who were depressed, 
it as found that they had the tendency to an increased rate of poorer self-

	  
37	  
reported role functionality(83). Self-reported low functional status could have 
been as a result of their emotional or physical conditions(83). Thus, it can be 
seen that an individual’s functional status may be considered subjective if 
patients are self-reporting and run the risk of being over-reported. However, it 
is an important aspect in determining the severity of depression which can 
impact on the overall well being of a patient. 
 
The Patient Health Questionnaire - 9 was chosen as to research tool in this 
study as it has been found to be a good screening tool for depression. It has 
been found to have a high sensitivity and negative predictive value, however, 
its sensitivity and a positive predictive value were low making it an excellent 
choice to screen patients for depression but not used to make a diagnosis(84). 
In our setting, it was applicable as the patients were willing to participate as 
the questionnaire only comprised a small number of questions. This made it 
easy to understand and not very time consuming, hence such a high 
respondent rate for the study. In addition, the Patient Health Questionnaire 9 
has been proven to be useful across different cultural groups when used with 
different ethnic groups which included African-Americans, Chinese-
Americans, Latinos and Whites(85) making it very useful in our setting which 
includes a variety of ethnic groups. One disadvantage of the Patient Health 
Questionnaire 9 is that it is not a diagnostic tool and thus, if patients score 
more than or equal to 10, they need further evaluation for the diagnosis of 
depression and using this questionnaire does not give a final diagnosis of 
depression(84). When the Patient Health Questionnaire 9 was compared to the 
Beck Depression Inventory II,  both were found to have adequate reliability, 
convergent/discriminant validity and similar responsiveness to change(86). 
There were differences in the categorization of the severity of depression 
between the two(86). The Patient Health Questionnaire 9 was chosen to be 
used in this study as it was shorter and would not prevent or delay patients’ 
clinic visits in the outpatient cardiology clinics. 
 
The Patient Health Questionnaire 9 was used in one study in specialized 
outpatient clinics in Japan to screen diabetic patients for depression, in which 
this screening tool was found to be useful and effective(87). It has also been 

	  
38	  
found that the Patient Health Questionnaire 9 is an excellent screening tool in 
the primary care setting too(84). Additionally, this screening tool was also 
used to screen in patients with cardiac disease in Trinidad and Tobago. Hence, 
it has been seen throughout the literature that the Patient Health Questionnaire 
is useful and effective both in an inpatient and outpatient setting. 
 
Of importance, in this study, patients who were found to have a PHQ score of 
greater than or equal to 10 were advised to seek further evaluation from a 
psychiatrist so that they can be formally assessed and diagnosed accurately. 
Once patients gave informed consent, these results were communicated to the 
physician who was attending to them in the cardiology outpatient clinic at Eric 
Williams Medical Sciences Complex, whereby routine medical care would be 
followed through and these patients would be given the appropriate referrals. 
It was reiterated to patients, that this questionnaire was a screening test and 
not a diagnostic test by any means. In the study, no respondents required 
admission to the emergency department at the Eric Williams Medical Sciences 
Complex.  
 
It was also found that there were positive correlations between the number of 
diseases and depression along with the number of medications a patient was 
taking and depression. This would be supported as different comorbidities as 
previously mentioned are associated with a higher risk of depression and thus 
these correlations were not surprising.  
 
In summary, it is evident that significant symptoms of depression were found 
in approximately 25% of patients with cardiac disease, which means one out 
of every four patients had depressive symptoms. Thus, closer attention is 
needed when it comes to screen such patient populations to assist in reducing 
the rates of morbidity and mortality and assist in compliance with medical 
therapies recommended. Additionally, further studies would be needed to 
evaluate if ticagrelor is independently associated with a higher risk of 
depression as found in this study. It should be noted that the Patient Health 
Questionnaire 9 is an excellent screening tool for depression and should not be 
used as a diagnostic tool by any means. Screening of depression should be 

	  
39	  
encouraged so that patients are effectively treated and patients who have 
depression are no longer underdiagnosed. 
 
Strengths and Limitations  
 
One of the major strengths if the study would be the number of participants of 
this study which was 1203 patients. This would have assisted to generalize the 
data that was analyzed across Trinidad and Tobago and give an idea of the 
incidence of depression amongst patients with cardiovascular disease across 
the country and have a greater impact on implementing therapy and making a 
change. Another strength worth mentioning in this study was the research site 
chosen, Eric Williams Medical Sciences Complex, as this is the only public 
health care tertiary institution that has a device cardiology outpatient clinic for 
cardiac patients with pacemakers, implantable cardioverter devices and 
chronic resynchronization therapy devices. Additionally, it is the only public 
health care institution which offers images services of CT coronary 
angiograms and cardiac MRIs along with invasive interventional cardiology 
procedures such as invasive coronary angiograms, percutaneous coronary 
intervention and coronary artery bypass graft surgery. Hence, this institution 
would have patients from the entire country and not just the north-central 
jurisdiction; including patients from San-Fernando, Port-of-Spain and Sangre 
Grande. This makes the data more plausible as it gives an overview of 
depression in cardiac patients with respect to most geographical locations of 
Trinidad and Tobago. 
 
The Patient Health Questionnaire-9 is a short and easy questionnaire which is 
easy to understand between all levels of education. Patients were more willing 
to participate as the questionnaires took an average time of 5 minutes for 
completion and it did not get in the way of their appointments to see the 
physician in the cardiology outpatient clinic. Any terminology on the 
questionnaire which was not understood was verbally explained that the 
person administering the questionnaires. It was also a good screening tool for 
depression as the results were easy to interpret and communicate to the 
doctors of the cardiology outpatient clinic as long as patients gave their 

	  
40	  
consent for this to be done. This made it easy for a routine medical practice to 
be implemented on site. 
 
There were some limitations of this study, one of which was the variability of 
patient responses with respect to questions being asked as this may have been 
inconsistent based on the patients’ current mood, location, time and health 
status. As the study is a cross-sectional study, it only represents the 
participants’ current feelings at one particular instance which is variable and 
likely to change. 
 
Another possible limitation of the study included the patients’ truthfulness 
with respect to their responses in the questions asked. Some responses may 
have intentionally not been the truth to prevent doctors’ concern for mental 
health rather than cardiovascular health or that patients may have been 
embarrassed to state how they really feel. 
 
As a result of needing the participants’ consent to communicate the results of 
the Patient Health Questionnaire-9 with the doctors in the clinic, some patients 
with major depression based on the responses, may not have been able to have 
appropriate psychological and psychiatry intervention if consent was not 
obtained. This would have prevented routine medical care to be implemented. 
 
Additionally, 9.8% of the respondent group did not have any confirmed 
diagnosis of cardiovascular disease as they were referred for the suspected 
diagnosis of cardiac disease but their investigations to confirm and provide 
objective evidence of cardiac disease were still pending. 
 
One last limitation of the study to be mentioned is that the research site of this 
study was only 1 out of 5 public health tertiary institutions and may not have 
provided an accurate representation of depression amongst patients with 
cardiac disease in Trinidad and Tobago. Thus, more studies similar to this one 
would need to be carried out to assess patients of the other public institutions. 
 
 

	  
41	  
CONCLUSION  
 
There is clear evidence to support the association of cardiovascular disease 
and significant symptoms of depression in Trinidad and Tobago. This finding 
is alarming and states in itself that depression is a condition which is 
tremendously undertreated in our setting. 1 in every 4 patient was found to 
have significant symptoms of depression in the sample population. Other 
factors may additionally influence the presence and severity of depression 
such as gender, lower levels of education and low socioeconomic factors, in 
particular, lower levels of income, which in all are all a multi-directional 
relationship. 
 
Data obtained from this study can assist in instituting policies in the 
cardiology outpatient clinics at Eric Williams Medical Sciences Complex for 
the screening of depression amongst this particular group of patients and 
possible aid in the start of implementing treatment. It may even contribute to 
lowering the morbidity and mortality rates secondary to cardiac disease as a 
result of increased adherence and compliance to treatment plans. 
 
Further studies are required at other public health tertiary institutions in 
Trinidad and Tobago to validate the findings of this study and assist to 
implement change to no longer understate depression associated with 
cardiovascular disease at a national level. 
 
 
 
 
 
 
 
 
 
 

	  
42	  
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