Pericranial and General Sensitivity in Patients With Primary Headache: a Multicenter Case-control Study
Conditions: Primary Headache Disorders, Tension Headache, Tension-type Headache, Migraine, Chronic Overlapping Pain Disorders
Sponsor: Universitat Internacional de Catalunya

 
 
 
 
 
 
 
Study number: REST-ECL-2025-07 
Protocol version: 2.0 
Version date: 4/6/2025 approved 
Submission date: 19/03/2025 
Principal Investigators: Cristian Justribo Manion, Jordi Tomàs Aliberas 
Secondary Investigators: Valentina Bustos Fuentealba, Natalia Felipe Spada 
Department: Restorative 
Research line: Foundations and research in applied dentistry 
Study title:“Pericranial and generalized sensitivity in patients with primary headache: a 
multicenter case-control study” 
 
 
 
 
 
 
 

 
 
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INTRODUCTION 
Headache is defined as pain located in the head, above the orbitomeatal line and or the nuchal 
crest(1). The primary classifications of headaches encompass primary headaches (PH), 
secondary headaches, painful neuropathy, other facial pain, and additional headache types(1). 
PH are not caused by or associated with an underlying disease. They can be differentiated from 
secondary headaches, which may exhibit similar phenotypic characteristics but fulfill the causal 
criteria of another disorder(1). PH, including migraine headache (MH), tension-type headache 
(TTH), and cluster headache (CH), are among the most common and disabling neurological 
disorders(2). Their pathophysiology is complex and multifactorial, involving genetic 
predisposition(3), central and peripheral nervous system dysfunction(3, 4), neurovascular 
interactions(5), and neuroinflammatory processes(4, 6). Each type of PH has distinct features, 
but there are overlaps that complicate diagnosis and treatment. A deeper understanding of 
these mechanisms is essential to guide more targeted and effective therapeutic strategies(7). 
Temporomandibular disorders (TMD), in contrast,  are a group of neuromuscular conditions 
related to the temporomandibular joint and all associated tissues(8). These disorders have a 
complex pathophysiology influenced by multiple risk factors(8). Although PH and TMD differ in 
classification, with PH considered primary pain disorders and TMD often categorized as 
secondary, both represent highly prevalent chronic pain conditions that significantly impact 
quality of life and healthcare systems(2, 9). Emerging evidence suggests that they may share 
overlapping pathophysiological mechanisms, including peripheral and central sensitization, 
altered pain modulation, and involvement of common trigeminal pathways(10). This shared 
neurobiological substrate may explain the frequent clinical comorbidity observed between TMD 
and PH(11). 
Related to PH, reviews have explored peripheral sensitization in TTH and MH. Castien et al. 
(2021)(12) reported that individuals with PH show greater pericranial tenderness than healthy 
controls, measured by the Total tenderness score (TTS). Findings from quantitative sensory 
testing (QST) studies, including the systematic review by van Welie et al. (2024)(13), show 
reduced pressure pain thresholds (PPT) in both trigeminal and extra-trigeminal sites, suggesting 
generalized hypersensitivity consistent with central sensitization. These findings emphasize the 
need to evaluate local and distant pain thresholds to distinguish between peripheral and central 
sensitization mechanisms in headache disorders(13). 

 
 
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Similar to PH, TMD are associated with peripheral sensitization related to tenderness in the 
masticatory system(14), and studies show pericranial tenderness increases with TMD 
severity(15). Meng et al. (2021)(16) reported evidence of decreased local and peripheral PPT 
sites related to TMD, supporting widespread mechanical hypersensitivity and central 
sensitization in these patients. Almoznino et al. (2019)(14) evaluated muscle tenderness in TMD 
patients using the TTS and examined whether comorbid PH affected tenderness severity. They 
found that patients with TMD and MH showed the highest pericranial and cervical tenderness, 
followed by those with TTH, suggesting a gradient of musculoskeletal hypersensitivity by 
headache type. However, the study did not assess extra-trigeminal regions, limiting conclusions 
about whether increased TTS reflects local peripheral mechanisms or broader central 
sensitization. In addition, because participants were recruited based on TMD and PH was treated 
as a comorbidity, the diagnostic interpretation is unclear: the subgroup with highest tenderness 
may represent individuals whose primary disorder is PH who happened to meet RDC/TMD 
criteria at evaluation, rather than patients with “TMD plus PH.” These limitations emphasize the 
need for studies that recruit patients based on PH diagnosis, assess TMD with DC/TMD, and 
characterize somatosensory phenotypes to clarify the bidirectional relationship. 
Beyond the overlap between PH and TMD, some patients present an even broader pattern of 
pain susceptibility. Individuals with TMD who exhibit widespread tenderness frequently show 
multiple chronic overlapping pain conditions (COPC), such as PH, low back pain, irritable bowel 
syndrome, chronic fatigue syndrome, and fibromyalgia(17, 18). Chen et al. (2012)(17) reported 
that TMD patients with widespread pain are significantly more likely to present several COPC 
compared to those without widespread pain or to non-TMD controls. Other studies have linked 
these comorbid conditions to greater TMD severity, longer pain duration, and poorer treatment 
response(19-21). This broader comorbidity profile suggests that widespread tenderness may 
reflect a systemic sensitization process rather than isolated regional dysfunction, underscoring 
the clinical relevance of routinely assessing COPC in patients with TMD. 
Both in TMD and PH, recent systematic reviews have identified similar methodological 
limitations that hinder clear interpretation and comparison across studies. In MH research, 
Welie et al. (2024)(13) noted considerable heterogeneity in QST protocols, with differences in 
stimulation modalities, anatomical test sites, and testing phases (ictal versus interictal) often 
poorly described. Similarly, Meng et al. (2021)(16) reported substantial variability in QST 
procedures for TMD, including inconsistent pressure rates, probe sizes, and selection of local or 

 
 
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extra-trigeminal sites. In both conditions, many studies relied on small samples and lacked 
appropriate stratification by migraine subtype (episodic versus chronic) or TMD subtype 
(myofascial versus arthralgia), as well as inadequate control of comorbid pain conditions or 
medication use, which may have biased results(16). Collectively, these methodological 
limitations highlight the need for standardized, adequately powered, and integrative studies 
assessing both local and widespread sensitivity to better delineate peripheral and central 
sensitization processes. 
Research has indicated that individuals with myofascial TMD are more prone to chronic daily 
headaches, MH, and episodic TTH(22). This suggests common underlying mechanisms, such as 
nociceptive pathway sensitization and dysfunction of endogenous pain modulation systems(23) 
To accurately investigate this overlap, a multidisciplinary approach integrating orofacial pain 
specialists and headache physicians is essential(24). In line with these recommendations, the 
present study will include patients with PH clinically diagnosed according to the ICHD-3 criteria, 
while TMD will be assessed, at the same time, using the standardized DC/TMD protocol. Cranial, 
facial, and cervical tenderness will be quantified through the TTS, and PPT will be measured at 
extratrigeminal sites to capture potential central sensitization phenomena. In addition, the 
number of COPC will be recorded, as a higher burden of comorbid pain conditions has been 
associated with increased headache frequency, greater TMD severity, and enhanced pain 
sensitivity.  
This integrative approach aims to clarify how peripheral factors reflected in orofacial and cervical 
tenderness, central mechanisms reflected in extratrigeminal hypersensitivity, and the presence 
of multiple COPC contribute to the clinical expression and overlap between TMD and headache. 
Furthermore, the concurrent assessment of both conditions will allow exploration of whether 
current DC/TMD criteria under-identify headache components when applied in isolation, 
highlighting the importance of adopting a multidisciplinary perspective in both diagnosis and 
treatment. 
Taken together, these considerations define a clear research gap: despite strong evidence of 
shared pathophysiological pathways between PH and TMD, no multicentric study has yet 
simultaneously assessed pericranial tenderness, extra-trigeminal hypersensitivity, and comorbid 
pain conditions under standardized protocols. Addressing this gap is essential to better 
understand the spectrum of sensitization and comorbidity in PH and their relationship with 
TMD. 

 
 
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 OBJECTIVES 
• 
To determine whether subjects with PH, both acute and chronic, have higher scores of 
pericranial and neck tenderness (local sensitivity), measured using the TTS, than healthy 
subjects. 
• 
To determine whether subjects with PH, both acute and chronic, have lower extra-
trigeminal PPT (generalized sensitivity), measured using an algometer, than healthy 
subjects. 
• 
To examine the association between the number of COPC and local sensitization 
processes, as reflected by increased pericranial tenderness measured with the TTS. 
• 
To examine the association between the number of COPC and peripheral sensitization 
processes, as reflected by reduced PPT at extra-trigeminal sites. 
• 
To explore the coexistence and overlap between TMD and PH, and to determine 
whether the presence of TMD is associated with greater local or generalized tenderness 
and a higher comorbidity burden. 
 
a. Hypothesis  
1. Hypothesis 1: It is hypothesized that patients with PH, especially those with chronic 
forms, will exhibit higher severity of pericranial and general tenderness compared to 
healthy subjects. 
2. Hypothesis 2: It is hypothesized that there is a positive correlation between the number 
of associated COPC and measures of central sensitization in relation to pericranial and 
peripheral sensitivity levels in patients with primary headaches. 
3. Hypothesis 3: It is hypothesized that there is a significant overlap in the diagnosis of 
myofascial TMD among patients with PH. Should this association be substantiated, it 
would be essential to document it, as it should be incorporated into the screening 
process for TMD, particularly within the PH anamnesis, to facilitate a more 
comprehensive and precise diagnostic evaluation. .. 
METHODS 
A cross-sectional  study will be conducted comparing two groups: i) PH group ii) Control 
group with no headaches, or with infrequent episodic headaches. Within the PH group, 

 
 
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if feasible, participants will be further classified into two subgroups: one with frequent 
episodic headaches (FEH) and one with chronic headaches (CH). Recruitment and 
observations will be carried out in a multicenter fashion, both in Spain and Germany. 
They will take place at the University of Manresa, the International University of 
Catalonia in Spain and at the University of Applied Sciences Osnabrück in Germany. The 
study protocol will be evaluated by the respective Ethics Committee (XX) and registered 
in ClinicalTrials.gov (XX). All participants will be informed about the aim of the study and 
sign an informed consent. The trial will follow the STROBE statement guidelines for 
reporting observational studies(25). 
a. Participants 
Participants will be recruited by convenience sampling by neurologists at the Barcelona 
Headache Unit of the Hospital Sant Joan de Deu de Manresa - Fundació Althaia, by 
Orofacial pain specialists at the University Clinic of the International University of 
Catalonia in Spain and by Pain/Orofacial pain specialists at a German Pain Center.  
Eligible participants must have a confirmed diagnosis of primary migraine or tension-
type headache or other PH, established by a headache specialist according to the 
International Classification of Headache 3 (ICHD-3)(1) and be under medical treatment 
for at least 6 months. All patients referred for evaluation will complete a self-assessment 
questionnaire, specially designed for this cross-sectional study and based on the ICHD-3 
criteria(1). It will be used to confirm the referred patient's diagnosis and classify the 
patient into episodic or chronic PH (see Appendix_1). It includes screening for migraine 
(codes 1.1, 1.2) and tension headache (codes 2.1, 2.2), as well as alert criteria for 
secondary headaches, such as thunderclap headache (code 4.6), post-traumatic 
headache (codes 5.1, 5.2), infection-related headache (code 9.1), intracranial pressure-
related headache (code 7.1.1) and headache with neurological deficit (code 6.2.2). The 
exclusion criteria will be the following: i) not understanding Spanish, English, or German; 
iii) severe dermatological problems or intraoral, head or neck injuries; iv) recent 
fractures; 
v) 
previous 
diagnosis 
of 
uncontrolled 
psychiatric 
disorder 
or 
neurodegenerative diseases; vi) recent onset of undiagnosed headache or unilateral 

 
 
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neck pain with associated neuropathic symptoms; and vii) pregnancy. Inclusion and 
exclusion criteria will be the same in all three recruitment centers. The person 
responsible for ensuring that all study participants meet the criteria will not be the same 
person responsible for evaluating the headache screening and self-assessment 
questionnaire.  
b. Factors of interest 
The principal investigator, a physiotherapist specialized in orofacial pain (Cristian 
Justribó-Manion), will be responsible for performing all assessments at the Spanish 
centers, including the pericranial and general sensitivity evaluation and the orofacial 
examination to identify pain-related TMD using the Spanish version of the DC/TMD(26). 
In the German center, the assessments will be conducted by a specialist in head and 
orofacial pain, who will apply the same procedures using the German version of the 
DC/TMD(27). At the same time, participants will use self-report scales to indicate the 
number of pain-associated comorbidities diagnosed by a physician, as well as the 
duration of their comorbid pain since diagnosis. The questionnaires will be administered 
by a person outside of the diagnostic process and assessment of the variables of interest. 
Self-reported questionnaires will be sent to participants via a secure web platform and 
data collection tool REDCAP. 
c. Control 
Healthy controls will be recruited by snowball sampling among students, university 
members, and related communities. Hypothetical controls will also complete the self-
assessment questionnaire based on the ICHD-3 criteria(1) to rule out that they do not 
meet a headache criterion. Volunteers who meet the criteria for a possible headache 
disorder will be advised to see a specialist, and those who qualify as cases will be invited 
to participate. This process ensures the selection of truly headache-free individuals for 
the control group and will blind the evaluators as any subject can be considered a case.  
The physiotherapist responsible for assessing the eligibility of both the interest group 
and the control group will not participate in the evaluation of sensitivity or any of the 

 
 
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variables assessed. The physiotherapist responsible (Jordi Padrós-Augé) is an expert in 
the clinical management of headaches, in the use of the ICDH-3 criteria(1) and is a 
professor at the University of Manresa and Director of the University Postgraduate 
Course "Expert in headaches and vestibular syndromes" taught at the University. 
Therefore, screening of participants recruited in all participating centers in Spain will be 
performed at the University of Manresa. In the German center, a specialist in head and 
orofacial pain will perform the screening of the subjects, will perform the DC/TMD, and 
classify participants to keep the blinding. 
d. Primary variables (sensitivity assessment) 
The primary dependent variable for this analysis will be the total pericranial tenderness 
score, secondary variable will be the overall PPT.  
For the assessment of the pericranial tenderness, the TTS protocol(12),  in which 
pericranial muscle tenderness is assessed by palpation of specific cranial and facial 
points, will be performed. This method has been widely used in previous studies to 
detect muscle tenderness and pain sensitivity in patients with TMD and headaches(12, 
14). Bilateral manual palpation of 8 pairs of muscle bodies and insertions (masseter, 
temporal, frontal, coronoid process, upper trapezius, sternocleidomastoid, suboccipital 
muscles and mastoid process). The second and third fingertips will be rotated for 4-5 
seconds(28). In accordance with validation guidelines(29) and previous clinical trial 
protocols(14, 30), muscle palpation shall be performed with approximately 1 kg of 
pressure. Prior to each assessment, assessors will calibrate using a digital algometer. The 
examiner will assess participants' reactions using a 4-point scale: 0 indicated no 
observable response or reported discomfort; 1 signified a mild facial reaction with no 
verbal indication of discomfort; 2 denoted both verbal and facial expressions of painful 
tenderness and discomfort; and 3 represented pronounced grimacing or withdrawal, 
accompanied by verbal reports of significant painful tenderness and pain22.  The 
maximum possible TTS was calculated as 48, derived by multiplying 8 painful points by 
2 (for the right and left sides) and then by 3 (the maximum score for each painful point). 

 
 
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TTS has been shown to be effective in assessing peri-cranial muscle tenderness in a 
variety of headaches. Studies have consistently shown that patients with TMD and 
headache, particularly those with tension headache and migraine, have higher TTS 
compared to healthy controls(14, 31). Research results have consistently shown that TTS 
is higher in subjects with chronic TTH  than in healthy controls. The pooled estimated 
mean difference was 1.57 (95% confidence interval 1.24 to 1.91)(12). For patients with 
migraine, the pooled estimated mean difference was 1.27 [95% confidence interval 0.91 
to 1.63](12). In the same direction, individuals with TMD-related myalgia showed a 
higher mean difference of 2.22 points and a standard error of 0.31 compared to healthy 
persons. 
In addition, overall pain sensitivity will be assessed using PPT measurements obtained 
with a portable digital algometry device (NOD A, OT Bioelettronica, Torino, Italy), 
equipped with a 1 cm² contact probe composed of biocompatible materials suitable for 
temporary skin contact.The NOD device incorporates a calibrated force sensor and 
provides real time visual biofeedback through a dedicated mobile application, allowing 
standardized control of the rate of pressure application. During the clinical assessment, 
the probe of the device will be positioned perpendicular to the participant’s skin at the 
selected anatomical sites. Pressure will be progressively applied while the examiner 
follows the visual guideline displayed by the application in order to maintain a constant 
rate of force increase. PPT measurements have been validated to assess general 
tenderness in both orofacial pain and generalized pain conditions, including TMDs and 
headaches(32). The NOD device has demonstrated good measurement reliability and 
validity when compared with established dynamometry systems used in clinical 
research. Validation studies have reported high levels of agreement with reference 
instruments such as the Jamar dynamometer, with intraclass correlation coefficients 
around 0.90, supporting its use as a reliable tool for force measurement in clinical and 
research settings(33). 
Participants will be notified of the gradual increase in pressure and instructed to raise 
their right index finger when they begin to perceive the pressure as uncomfortable. 

 
 
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Measurements were taken at three commonly used anatomical sites(28, 34) following 
a randomization: 
● Tibialis anterior muscle (Evaluated in the central region of the muscle, with the 
participant supine). 
● Radial carpal extensor (Measured at the dorsal aspect of the wrist joint line, with 
the participant in the supine position). 
● Low back (Examined in the interspinous space between L5 and S1, with the 
participant lying face down). 
The assessor will apply pressure consecutively in each zone. After applying pressure to 
the three zones, the subjects will be allowed to rest for 5 min. This procedure will be 
repeated a total of 3 times. The mean of the three assessments will be recorded. This 
approach helps to avoid possible hypervigilance of the individual during the first 
assessment, which increases reliability(35) (Cronbach's alpha: 0.94-0.98). In previous 
research, a minimal detectable difference in the tibialis anterior of 1.24 kg/cm2 (CI: 0.76-
2.03) was observed. The mean for each body zone and the overall mean extra trigeminal 
sensitivity will be calculated. 
e. Secondary variables 
The key covariates to be examined will cover the occurrence of TMD according to the 
Spanish/German version of the DC/TMD(26, 27), the total central sensitization score and 
the number of coexisting conditions identified using the Central Sensitization Inventory 
(CSI) (Spanish/German versions)(36, 37), a pain body drawing(38) and the intensity of 
pain using the Brief pain inventory short form (BPI-SF) (Spanish/German versions)(39, 
40).  
Individuals with a positive diagnosis of pain-related TMD will be classified as: i) 
Arthralgia: Joint pain as the only pain symptom ii) Myalgia: Muscle pain as the only pain 
symptom iii) Myalgia and Arthralgia (mixed pain) iv) Headache attributed to TMD: 
Patients with arthralgia or myalgia and headache attributed to TMD. The Diagnostic 

 
 
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Criteria for Temporomandibular Disorders (DC/TMD) have demonstrated a sensitivity of 
≥0.86 and specificity of ≥0.98 for the most common pain-related TMD(38).  
The initial section of the CSI, Part A, will be used to assess overall sensitization scores. 
This part examines 25 health-related symptoms commonly associated with central 
sensitization, with scores ranging from 0 to 100. A score of 40 or higher suggests central 
sensitization. A score of 40 or higher suggests central sensitization. Part B, which is not 
scored, inquires about previous diagnoses of specific disorders, including seven distinct 
central sensitization syndromes. The researchers incorporated chronic low back pain as 
an additional syndrome. This addition is consistent with their previous research, which 
demonstrated a strong correlation between low back pain and these syndromes(18, 41). 
The Spanish/ German adaptation of the CSI has demonstrated a satisfactory threshold 
of 75% for both sensitivity and specificity in the identification of centrally sensitive 
syndromes. In addition, it has shown strong internal consistency (α = 0.872) and 
excellent test-retest reliability (r = 0.91) (36, 37).  
The BPI-SF will be used to quantify pain intensity and pain-related interference. It 
provides two summary scores ranging from 0 to 10, where higher values indicate greater 
pain burden. The instrument shows good measurement reliability(39, 40), with a 
standard error of measurement of approximately 1.6 points and a minimal detectable 
change of about 2 points, indicating that reductions of this magnitude in pain severity 
and approximately 1 point in pain interference represent clinically meaningful 
improvement(42). In addition, a pain body drawing will be used to document the 
distribution of pain, allowing the identification of widespread pain patterns and 
facilitating the classification of participants according to the presence or absence of 
multisite pain. 
Cervical motor and sensorimotor variables will also be assessed using the NeckCare 
System (NeckCare, Reykjavík, Iceland), a wearable sensor-based platform designed to 
provide objective assessment of cervical spine function. The system uses a lightweight 
head mounted sensor connected via Bluetooth to a computer platform that records 
cervical kinematics in real time and generates automated reports of cervical 

 
 
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performance. It allows clinicians to objectively evaluate cervical range of motion, 
proprioception, and sensorimotor control during standardized clinical tests. Active 
cervical range of motion (ROM) will be recorded for flexion, extension, right and left 
rotation, and right and left lateral flexion. The system quantifies cervical motion in 
degrees while tracking movement patterns and symmetry across planes. Cervical 
proprioception will be assessed using the Joint Position Error (JPE) test. In this 
procedure, the participant performs active cervical movements and subsequently 
attempts to relocate the head to the initial neutral position without visual feedback. The 
system automatically calculates the repositioning error in degrees, providing an 
objective measure of cervical joint position sense. Sensorimotor control will be further 
evaluated using the Butterfly Test®. In this test, the participant attempts to follow a 
moving visual target on a computer screen using head movements tracked by the 
sensor. The platform compares the trajectory of the head movement with the target 
path and quantifies movement accuracy, smoothness, and coordination between the 
visual, vestibular, and cervical motor systems. 
Finally, the Maximum voluntary contraction and endurance of the cervical flexor 
muscles will be assessed using a portable digital dynamometry and biofeedback device 
(NOD A, OT Bioelettronica, Torino, Italy). The device incorporates a calibrated force 
sensor and provides real time visual feedback through a dedicated mobile application, 
allowing participants to monitor the target force during testing. 
All measurements will be performed with the participant in a supine position on an 
examination table. A support cushion will be placed under the occipital region to 
maintain a standardized head position. The force sensor of the NOD device will be 
positioned on the participant’s forehead and secured with a fixation strap to ensure 
stable contact during the test. 
Participants will first perform two maximal voluntary contractions (MVC) of the cervical 
flexor muscles by pressing the forehead against the device while maintaining the head 
supported on the examination table. The mean value of the two maximal force 
recordings will be calculated and used as the reference MVC. 

 
 
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Subsequently, a cervical flexor endurance test will be conducted. Participants will be 
instructed to maintain a contraction corresponding to 25 percent of their previously 
determined MVC for as long as possible. Real time visual biofeedback will be provided 
by the device, allowing participants to monitor the percentage of force produced and 
maintain the target contraction level within a tolerance margin of ±5 percent of the 
prescribed force. Endurance time will be recorded as the duration for which the 
participant is able to maintain the required force within the predefined target range. 
Figure 1 shows the flow chart of the study, which summarizes the main phases of the 
process: selection of participants, random assignment to a diagnostic group and 
evaluation.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 1. Diagram of the study flowchart. Abbreviations: Central Sensitization Inventory CSI, Pain 
Pressure Threshold PPT, DCTMD Diagnostic Criteria for Temporomandibular Disorders. 
 Assignment 
Controls 125  
 
 
Assessments: Total Tenderness 
Score, extra trigeminal PPT, 
DCTMD, CSI A, CSI B, BPI-SF 
Comorbidities and pain drawing   
Cases ≥ 60 
Very frequent 63 
Chronic 62 
Headache Screening  
Headache Screening  
 Assignment 
Confirmed  
No headache 
Confirmed  
No headache 
Selection by experts 
Selection by experts 
 Phase 1: Hospital Sant Joan de Deu 
Manresa and Universitat Internacional 
Catalunya Spain 
 Phase 2: University of Applied Sciences 
Osnabrück Germany 
Recruitment 
Assessments: Total Tenderness 
Score, extra trigeminal PPT, 
DCTMD, CSI A, CSI B, BPI-SF 
Comorbidities and pain drawing   

 
 
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Statistical analysis 
All statistical analyses will be performed with R version 4.4.2. The pwr(43) package was 
used to calculate the sample size.  In a previous study, Almoznino et al.(14) analyzed the 
differences in pericranial sensitivity between 44 subjects with myalgia-associated TMD 
and 99 healthy controls. They reported a mean difference of -2.22 with a standard error 
of 0.31, measured using the TTS. Using the formula (Standard deviation = Standard error 
we calculated a standard deviation of 3.71. For our study, we considered a one-to-one 
ratio between the groups and a one-sided contrast, as we expect the effect to be biased 
toward the group of patients with headache. The sample size was determined using an 
alpha level of 0.05 and a statistical power of 0.90. Since this study has no follow-up, we 
assumed no loss of participants. The calculation determined that each group should 
have a minimum of 60 subjects to detect a clinically significant difference. To further 
strengthen the study, we intend to recruit a larger sample for the development of 
prediction models using all subjects evaluated. The sample size calculation for prediction 
modeling was based on an expected R² of 0.6, a maximum of 10 parameters, an alpha 
level of 0.05 and a power of 0.8. As no participant losses are expected, we set the 
reduction factor to 0%. According to these parameters, the total sample size needed for 
the prediction model is 250 participants in total. We estimate to recruit 80 cases and 80 
controls at the Barcelona Headache Unit of the Hospital Sant Joan de Deu de Manresa, 
25 cases and 25 controls at the dental clinic of the UIC and 20 cases and 20 controls at 
the Osnabrück University of Applied Sciences. 
Descriptive statistics will be used to summarize the data. Continuous variables will be 
expressed as mean ± standard deviation (SD) if normally distributed, or as median and 
interquartile range (IQR) if non-normally distributed. Categorical variables will be 
presented as absolute and relative frequencies. Comparisons between groups will be 
made using independent t-tests for normally distributed continuous variables or Mann-
Whitney U-tests for non-normally distributed data. The presence of TMD will be 
compared by Chi-square tests, or Fisher's exact test when the expected frequencies are 
low. Correlation between pericranial sensitivity and severity of general sensitivity with 

 
 
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other factors will be assessed by Pearson's correlation for normally distributed data or 
Spearman's correlation otherwise. 
To assess the levels of pericranial and general sensitivity in patients with primary 
headaches and to compare individuals with acute and chronic conditions with healthy 
controls (Objective 1), descriptive statistics and group comparisons will be performed. 
Mean values and standard deviations of sensitivity measures between groups will be 
calculated, and appropriate statistical tests, such as ANOVA or Kruskal-Wallis, will be 
used to detect significant differences. Pairwise comparisons will be adjusted for multiple 
testing when necessary. 
To examine the association between the total number of comorbidities and central 
sensitization with pericranial sensitivity (Objective 2), multivariable regression models 
will be used to determine prognostic relationships. Pericranial and overall sensitivity will 
be set as dependent variables in separate models, whereas total number of 
comorbidities, central sensitization score, and up to 10 relevant cofactors will be 
included as independent variables. Collinearity between exposure factors will be tested 
using the variance inflation factor (VIF) to exclude confounders, where a VIF of 1 
indicates no collinearity(44). The adjusted R², the statistical significance of the final 
model, the B coefficient, the standard error (SE), the standardized B coefficient and the 
significance for each factor will be reported. The p-value will be interpreted according 
to Sterne and Smith(45) , where *p ≤ .001 indicates strong evidence, p between .001 
and .05 indicates good evidence, p between .05 and .10 indicates moderate evidence, 
and p > .10 indicates weak evidence. The R² effect size will be interpreted following 
Cohen(46) as 0.02 (small), 0.15 (medium), and 0.35 (large). 
To examine the overlap between temporomandibular disorders (TMD) and primary 
headaches (Objective 3), the presence of TMD will be assessed using the Diagnostic 
Criteria for Temporomandibular Disorders (DC/TMD). Chi-square tests or logistic 
regression models will be used to identify significant patterns of coexistence between 
these conditions. The strength of associations will be quantified using odds ratios (ORs) 

 
 
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and confidence intervals (CIs) to determine whether individuals with primary headaches 
are at significantly increased risk for TMD compared to healthy controls. 
4. PLANNING 
Phase 1: The study protocol was approved by the Ethics Committee (CEIm) of the 
International University of Catalonia, Spain, on June 4, 2025. Subsequently, the protocol 
will be submitted for approval to the CEIm IRIS-CC of the University of Manresa, Spain, 
and to the Ethics Committee of the University of Applied Sciences Osnabrück, Germany. 
Phase 2: Recruitment and evaluation at the International University of Catalonia, Spain 
, and at the Osnabrück University of Applied Sciences, Germany. March 1 to December 
7, 2026. Data analysis and manuscript writing, with a deadline of early March 2027. 
Phase 4: Publication, with a deadline of December 2028. 
5. LINK BETWEEN MOBILITY AND THE LINE OF RESEARCH 
The international mobility aspect of the project plays a key role in enhancing the 
research line by providing access to specialized resources, expertise and methodologies. 
The collaboration between the University of Manresa and the Osnabrück University of 
Applied Sciences fosters the intercultural exchange of knowledge, especially in the field 
of orofacial pain. Through the mobility, the researcher will come into contact with 
advanced research in orofacial physiotherapy, led by Dr. Susan Armijo-Olivo, and will be 
able to integrate this knowledge into research. This movement between institutions will 
contribute to the improvement of research methods and facilitate a comprehensive 
approach to understanding and addressing orofacial pain. 
 
 
 
Principal Investigator 
s/he is Dr./Dr. 

 
 
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Appendix_1 Screening for Headaches 
Self-Assessment Form for Screening Healthy Participants and Headaches. 
Instructions: Answer the following questions honestly. If you answer "Yes" in certain 
sections, you may not meet the criteria to participate in the study. 
I. General Information. 
● Patient Code: ______________________ 
● Age: _______ 
● Sex:☐ Male☐ Female☐ Other 
● Date of birth: //____ 
● Height (cm): _______ 
● Weight (kg): _______ 
● Do you currently smoke? ☐ Yes☐ No 
● Do you consume alcohol regularly? ☐ Yes☐ No 
 
II. History of Headache 
1. Have you had a headache in the last 3 months? ☐ Yes☐ No 
o If NO, go to section IV. 
2. If yes, how often do you usually have a headache? 
 
Average number of days with headache per month: _______ 

 
 
18 
 
Minimum number of headache days per month: _______ 
Maximum number of headache days per month: _______ 
3. From what age do you experience headaches? _______ 
4. Have you been diagnosed with any type of headache (migraine, tension 
headache, etc.) by a physician? ☐ Yes☐ No 
o If "Yes", please indicate diagnosis: (select from the list) List: migraine, 
migraine with aura, tension type headache, cluster headache, 
SUNCT/SUNA, hemicrania continua, paroxysmal hemicrania, primary 
cough headache, primary exercise headache, primary headache 
associated with sexual activity, primary thunderclap headache, 
nummular headache, hypnic headache, new daily persistent headache, 
other headache.) 
5. Do you take medication regularly for headaches? ☐ Yes☐ No 
Category 
Medications 
Duration (months) / Frequency 
(days/month) 
Analgesics 
Paracetamol, Acetylsalicylic acid, Naproxen 
 
Triptans 
Sumatriptan, Rizatriptan, Zolmitriptan, Almotriptan, 
Eletriptan, Naratriptan, Frovatriptan 
 
Opioids 
Tramadol, Codeine, Morphine, Fentanyl, Oxycodone, 
Hydromorphone 
 
Ergot derivatives 
Dihydroergotamine 
 
Beta-blockers 
Propranolol, Metoprolol 
 
Antiepileptics 
Topiramate, Sodium valproate 
 
Antidepressants 
Amitriptyline 
 
Migraine 
preventive 
Botulinum toxin, Anti-CGRP monoclonal antibodies 
(Erenumab, Fremanezumab, Galcanezumab, 
Eptinezumab) 
 
Oxygen therapy 
Oxygen 
 

 
 
19 
 
Indomethacin 
Indomethacin 
 
Gepants 
Ubrogepant, Rimegepant, Atogepant 
 
Ditans 
Lasmiditan 
 
6. How long have you been taking medication to treat your headache? 
______________________ 
 
III. Characteristics of Headache 
How long does a typical episode of your headache last? (choose the answer that 
fits better for your headache attacks) 
☐ Seconds 
☐ 2-10 minutes 
☐ 10-30 minutes 
☐ Hours to 3 days (when untreated) 
☐ More than 3 days 
When you have a headache, is it usually...? 
☐ Unilateral (affects only one side of the head) 
☐ Bilateral (affects both sides of the head) 
Is the pain usually...? 
☐ Throbbing (like a heartbeat) 
☐ Oppressive (like a band around the head) 
☐ Other: ________________ 
Does the pain get worse with physical activity? ☐ Yes☐ No 

 
 
20 
 
Is the headache accompanied by one of the following?  (Check all that apply) 
☐ Nausea 
☐ Vomiting 
☐ Sensitivity to light (photophobia) 
☐ Sensitivity to noise (phonophobia) 
☐ Visual or sensory aura before headache 
☐ None of the above 
 
IV. Evaluation of Possible Secondary Headaches 
10. Has the pain changed in intensity, frequency or pattern in the last month? 
 ☐ Yes  
☐ No 
11. Is your headache accompanied by fever, unexplained weight loss, or night 
sweats?  
☐ Yes  
☐ No 
12. Have you suffered a head injury or traffic accident that initiated or worsened 
your headache?  
☐ Yes  
☐ No 
13. The headache is preceded in the previous minutes by: 
Double vision  
☐ Yes  
☐ No 
Difficulty in speaking  
☐ Yes  
☐ No 
Weakness or numbness 
 
☐ Yes  
☐ No 

 
 
21 
 
14. Is the pain made worsened or triggered by coughing, sneezing, or changing 
position?  
☐ Yes  
☐ No 
 
Participant's Signature 
I declare that the information provided is true and complete. 
Signature: ________________________ 
Date: //____ 
 
 

 
 
22 
 
Healthy Subject Inclusion Criteria 
  You are considered "healthy" if: 
● Answers "NO" to all questions in section IV (rule out secondary headache). 
● You do not have a medical diagnosis of primary headache or take medication for 
it. 
● If you have had headaches, they are occasional and without symptoms indicative 
of 
migraine or tension headache. 
 Will be excluded if: 
● You answer "Yes" to any question in section IV. 
● Frequent use of headache medication. 
The answers will be evaluated by a Headache Physiotherapist to categorize the patient 
into Primary, Episodic, Chronic or other Secondary Headache.  
 
Figure XX. Screening diagram for headaches 
 

 
 
23 
 
Appendix 2_ICHD-3 Glossary of Headache Terms 
 
1.1 Migraine without aura 
Recurrent headache of moderate or severe intensity, unilateral localization, throbbing, 
worse with physical activity and may be accompanied by nausea, vomiting, photophobia 
or phonophobia. 
 
1.2 Migraine with aura 
A form of migraine preceded or accompanied by reversible neurological symptoms, 
typically visual (such as flashes of light or partial loss of vision), but may also include 
sensory or speech disturbances. 
 
2.1 Infrequent episodic episodic tension headache 
Mild to moderate, oppressive or band-like, bilateral headache that does not worsen with 
physical activity and is not usually associated with nausea. Occurs less than once a 
month. 
 
2.2 Frequent episodic tension headaches 
Similar to the previous one, but with a higher frequency (1-14 days per month), which 
may affect quality of life. 
 
4.6 Thunderclap headache 
Headache with abrupt onset and maximum intensity in less than one minute. May be a 
sign of serious pathologies such as subarachnoid hemorrhage and requires urgent 
evaluation. 
 
5.1 Acute post-traumatic headache 
Headache that appears within 7 days of a head injury and lasts less than 3 months. 
 
5.2 Persistent post-traumatic headache 

 
 
24 
 
Headache that persists beyond 3 months after a head injury. 
 
6.2.2 Headache attributed to ischemic or hemorrhagic stroke 
Headache associated with stroke (cerebral infarction or hemorrhage), with focal 
neurological symptoms. 
 
7.1.1 Headache attributed to idiopathic intracranial hypertension (pseudotumor 
cerebri) 
Headache caused by increased intracranial pressure with no identifiable cause on 
neuroimaging. May be associated with blurred vision, tinnitus and pain that worsens on 
lying down. 
 
9.1 Headache attributed to intracranial or systemic infection 
Headache secondary to infections such as meningitis, encephalitis or severe systemic 
infections, often accompanied by fever and other general or neurological symptoms. 
 
 
 

 
 
25 
 
References 
1. 
Headache Classification Committee of the International Headache Society 
(IHS) The International Classification of Headache Disorders, 3rd edition. 
Cephalalgia. 2018;38(1):1-211. 
2. 
Stovner LJ, Hagen K, Linde M, Steiner TJ. The global prevalence of headache: 
an update, with analysis of the influences of methodological factors on prevalence 
estimates. J Headache Pain. 2022;23(1):34. 
3. 
Wang Z, Yang X, Zhao B, Li W. Primary headache disorders: From 
pathophysiology to neurostimulation therapies. Heliyon. 2023;9(4). 
4. 
Edvinsson L, Uddman R. Neurobiology in primary headaches. Brain Research 
Reviews. 2005;48(3):438-56. 
5. 
Shibata Y. Migraine Pathophysiology Revisited: Proposal of a New Molecular 
Theory of Migraine Pathophysiology and Headache Diagnostic Criteria. 
International Journal of Molecular Sciences [Internet]. 2022; 23(21). 
6. 
Musubire AK, Cheema S, Ray JC, Hutton EJ, Matharu M. Cytokines in primary 
headache disorders: a systematic review and meta-analysis. The Journal of 
Headache and Pain. 2023;24(1):36. 
7. 
Onan D, Younis S, Wellsgatnik WD, Farham F, Andruškevičius S, Abashidze A, 
et al. Debate: differences and similarities between tension-type headache and 
migraine. J Headache Pain. 2023;24(1):92. 
8. 
Leeuw RD Klasser G e. Orofacial Pain. Guidelines for Assessment, Diagnosis, 
and Management. American Academy of Orofacial Pain.: ed. Quintessence 
Publishing Company; 2018. 
9. 
Alqutaibi AY, Alhammadi MS, Hamadallah HH, Altarjami AA, Malosh OT, 
Aloufi AM, et al. Global prevalence of temporomandibular disorders: a systematic 
review and meta-analysis. Journal of Oral & Facial Pain and Headache. 
2025;39(2):48-65. 
10. 
Conti PC, Costa YM, Gonçalves DA, Svensson P. Headaches and myofascial 
temporomandibular disorders: overlapping entities, separate managements? J Oral 
Rehabil. 2016;43(9):702-15. 
11. 
Dibello V, Lozupone M, Sardone R, Ballini A, Lafornara D, Dibello A, et al. 
Temporomandibular Disorders as Contributors to Primary Headaches: A 
Systematic Review. J Oral Facial Pain Headache. 2023;37(2):91-100. 
12. 
Castien R, Duineveld M, Maaskant J, De Hertogh W, Scholten-Peeters G. 
Pericranial Total Tenderness Score in Patients with Tension-type Headache and 
Migraine. 
A 
Systematic 
Review 
and 
Meta-analysis. 
Pain 
Physician. 
2021;24(8):E1177-e89. 
13. 
van Welie FC, Dahan A, van Velzen M, Terwindt GM. Pain profiling in migraine: 
a systematic review of Quantitative Sensory Testing (QST), Conditioned Pain 
Modulation (CPM), and Corneal Confocal Microscopy (CCM). The Journal of 
Headache and Pain. 2024;25(1):224. 
14. 
Almoznino G, Zini A, Zakuto A, Zlutzky H, Bekker S, Shay B, et al. Muscle 
tenderness score in temporomandibular disorders patients: A case-control study. J 
Oral Rehabil. 2019;46(3):209-18. 

 
 
26 
 
15. 
Bevilaqua-Grossi D, Chaves TC, de Oliveira AS, Monteiro-Pedro V. 
Anamnestic index severity and signs and symptoms of TMD. Cranio. 2006;24(2):112-
8. 
16. 
Meng H, Dai J, Li Y. Quantitative sensory testing in patients with the muscle 
pain subtype of temporomandibular disorder: a systemic review and meta-analysis. 
Clinical Oral Investigations. 2021;25(12):6547-59. 
17. 
Chen H, Slade G, Lim PF, Miller V, Maixner W, Diatchenko L. Relationship 
between temporomandibular disorders, widespread palpation tenderness, and 
multiple pain conditions: a case-control study. J Pain. 2012;13(10):1016-27. 
18. 
Kleykamp BA, Ferguson MC, McNicol E, Bixho I, Arnold LM, Edwards RR, et 
al. The prevalence of comorbid chronic pain conditions among patients with 
temporomandibular disorders: A systematic review. J Am Dent Assoc. 
2022;153(3):241-50.e10. 
19. 
Dahan H, Shir Y, Velly A, Allison P. Specific and number of comorbidities are 
associated with increased levels of temporomandibular pain intensity and duration. 
J Headache Pain. 2015;16:528. 
20. 
Justribó-Manion C, Padrós-Augé J, Mesa-Jiménez J, Bara-Casaus J, Zuil-
Escobar JC, Alvarez Bustins G. Assessment of chronic overlapping pain 
comorbidities for the management of temporomandibular disorders: Secondary 
analysis of a randomized clinical trial. Physiother Theory Pract. 2024:1-16. 
21. 
Kamaleri Y, Natvig B, Ihlebaek CM, Bruusgaard D. Does the number of 
musculoskeletal pain sites predict work disability? A 14-year prospective study. Eur 
J Pain. 2009;13(4):426-30. 
22. 
Gonçalves DA, Camparis CM, Speciali JG, Franco AL, Castanharo SM, Bigal 
ME. Temporomandibular disorders are differentially associated with headache 
diagnoses: a controlled study. Clin J Pain. 2011;27(7):611-5. 
23. 
Bevilaqua Grossi D, Lipton RB, Bigal ME. Temporomandibular disorders and 
migraine chronification. Curr Pain Headache Rep. 2009;13(4):314-8. 
24. 
Glaros AG, Urban D, Locke J. Headache and temporomandibular disorders: 
evidence for diagnostic and behavioural overlap. Cephalalgia. 2007;27(6):542-9. 
25. 
von Elm E, Altman DG, Egger M, Pocock SJ, Gøtzsche PC, Vandenbroucke JP. 
The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) 
statement: guidelines for reporting observational studies. J Clin Epidemiol. 
2008;61(4):344-9. 
26. 
González Y, Rivera Y, Espinosa I. Adaptación transcultural de los criterios 
diagnósticos para la investigación de los trastornos temporomandibulares 
(CDI/TTM). Rev Fac Odontol Univ Antioq. 2013;25:11-25. 
27. 
Asendorf A, Möllenkamp J, Schierz O, Rauch A, Asendorf T, Rammelsberg P, 
et al. Interexaminer reliability of the German version of the DC/TMD. J Oral Rehabil. 
2021;48(1):28-34. 
28. 
Fernández-de-Las-Peñas C, Plaza-Manzano G, Navarro-Santana MJ, Olesen 
J, Jensen RH, Bendtsen L. Evidence of localized and widespread pressure pain 
hypersensitivity in patients with tension-type headache: A systematic review and 
meta-analysis. Cephalalgia. 2021;41(2):256-73. 

 
 
27 
 
29. 
Schiffman EL, Ohrbach R, Truelove EL, Tai F, Anderson GC, Pan W, et al. The 
Research Diagnostic Criteria for Temporomandibular Disorders. V: methods used to 
establish and validate revised Axis I diagnostic algorithms. J Orofac Pain. 
2010;24(1):63-78. 
30. 
Aaseth K, Grande RB, Lundqvist C, Russell MB. Pericranial tenderness in 
chronic tension-type headache: the Akershus population-based study of chronic 
headache. J Headache Pain. 2014;15(1):58. 
31. 
Ashina S, Bendtsen L, Lyngberg AC, Lipton RB, Hajiyeva N, Jensen R. 
Prevalence of neck pain in migraine and tension-type headache: a population study. 
Cephalalgia. 2015;35(3):211-9. 
32. 
Deodato M, Granato A, Martini M, Sabot R, Buoite Stella A, Manganotti P. 
Instrumental assessment of pressure pain threshold over trigeminal and extra-
trigeminal area in people with episodic and chronic migraine: a cross-sectional 
observational study. Neurol Sci. 2024;45(8):3923-9. 
33. 
Sartorio F, Lippi L, Vercelli S, Gallo F, Zanin D, Bergesio S, et al. Reliability and 
validity of the hand-held dynamometer "NOD": a new instrument for assessment of 
isometric grip strength. BMC Musculoskelet Disord. 2025;26(1):5. 
34. 
Knuutila J, Kivipuro J, Näpänkangas R, Auvinen J, Pesonen P, Karppinen J, et 
al. Association of temporomandibular disorders with pain sensitivity: A cohort 
study. Eur J Pain. 2022;26(1):143-53. 
35. 
Park G, Kim CW, Park SB, Kim MJ, Jang SH. Reliability and usefulness of the 
pressure pain threshold measurement in patients with myofascial pain. Ann Rehabil 
Med. 2011;35(3):412-7. 
36. 
Klute M, Laekeman M, Kuss K, Petzke F, Dieterich A, Leha A, et al. Cross-
cultural adaptation and validation of the German Central Sensitization Inventory 
(CSI-GE). BMC Musculoskelet Disord. 2021;22(1):708. 
37. 
Cuesta-Vargas AI, Roldan-Jimenez C, Neblett R, Gatchel RJ. Cross-cultural 
adaptation and validity of the Spanish central sensitization inventory. Springerplus. 
2016;5(1):1837. 
38. 
Schiffman E, Ohrbach R, Truelove E, Look J, Anderson G, Goulet JP, et al. 
Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) for Clinical and 
Research Applications: recommendations of the International RDC/TMD 
Consortium Network* and Orofacial Pain Special Interest Group†. J Oral Facial Pain 
Headache. 2014;28(1):6-27. 
39. 
de Andrés Ares J, Cruces Prado LM, Canos Verdecho MA, Penide Villanueva 
L, Del Valle Hoyos M, Herdman M, et al. Validation of the Short Form of the Brief Pain 
Inventory (BPI-SF) in Spanish Patients with Non-Cancer-Related Pain. Pain Pract. 
2015;15(7):643-53. 
40. 
Radbruch L, Loick G, Kiencke P, Lindena G, Sabatowski R, Grond S, et al. 
Validation of the German version of the Brief Pain Inventory. J Pain Symptom 
Manage. 1999;18(3):180-7. 
41. 
Justribó-Manion C, Mesa-Jiménez J, Caballero-Ruiz-de-la-Hermosa C, Zuil 
Escobar JC, Armijo-Olivo S. Is low back pain a risk/prognostic factor for the 
development and/or progression of temporomandibular disorders? A systematic 
review with meta-analysis. J Oral Rehabil. 2024;51(2):427-54. 

 
 
28 
 
42. 
Mathias SD, Crosby RD, Qian Y, Jiang Q, Dansey R, Chung K. Estimating 
minimally important differences for the worst pain rating of the Brief Pain Inventory-
Short Form. J Support Oncol. 2011;9(2):72-8. 
43. 
Champely S. pwr: Basic functions for power analysis. Version 1.3-0. CRAN; 
2020. from: 10.32614/CRAN.package.pwr  [ 
44. 
Johnston R, Jones K, Manley D. Confounding and collinearity in regression 
analysis: a cautionary tale and an alternative procedure, illustrated by studies of 
British voting behaviour. Qual Quant. 2018;52(4):1957-76. 
45. 
Sterne JA, Davey Smith G. Sifting the evidence-what's wrong with 
significance tests? Bmj. 2001;322(7280):226-31. 
46. 
Cohen J. A power primer. Psychol Bull. 1992;112(1):155-9.