Review for 10.1186/s12876-017-0712-8 (2017)

Reviewer ’s report  
 
Title:  Risk Factors For Mortality Among Patients Admitted With Upper Gastrointestinal 
Bleeding At A Tertiary Hospital: A Prospective Cohort Study  
 
Version: 0 Date: 05 Mar 2017 
 
Reviewer:  Hsiu -Chi Cheng  
 
Reviewer’s report:  
 
Review on BMGE -D-17-00085 by Moledina SM et al., entitled "Risk factors for mortality 
among patients admitted with upper gastrointestinal bleeding at a tertiary hospital: a prospective 
cohort study"  
 
This study identified the cause of upper gastrointestinal bleeding and factors that increase the 
risk of mortality in these patients in Tanzania.   
 
The following comments are for the reference of authors:  
 
Major comments  
 
1. The first aim of the study was to identify the causes of upper gastrointestinal bleeding. 
The second aim was to identify risk factors for mortality. The authors found that 
oesophageal varices bleeding was the most common cause of upper gastrointestinal 
bleeder and a high WBC count, rais ed serum ALT, raised serum total bilirubin, and lack 
of endoscopy were four independent predictors of mortality. Two of the predictors were 
correlated to liver function. Thus, these results may reflect the endemic disease in 
Tanzania, i.e., chronic liver d isease. Consequently, the cause of upper gastrointestinal 
bleeding and the risk factors for mortality were almost correlated to chronic liver disease. 
The strength is that the study identified an important issue in a local area but the 
weakness is its poor  generalisability.  
 
2. In the "Method" regarding selection bias: because half of the patients did not undergo 
endoscopy, the enrolled patients in this study were a "very special" cohort. The reasons 
why the percentage of lack of endoscopy was so high in Tan zania should be further 
studied; nevertheless, it may raise an important issue which should be improved in 
clinical care in this country.     
 
3. In the "Method" regarding measurement bias: The definitions of mortality and recurrent 
bleeding were well defin ed. However, the definition of upper gastrointestinal bleeding 
should be addressed.     
 
4. In the "Method" regarding confounding bias. Renal insufficiency, encephalopathy on 
admission, and HIV infection were three factors correlated to "lack of endoscopy" (lines 
15th-17th, page 6). These factors were also possibly correlated to "mortality". Thus, these 
factors were potentially confounding the correlation of "lack of endoscopy" and 
"mortality". The authors used Cox regression analysis to deal with the potent ial 
confounding factors and identify the independent factors to predict 60 -day mortality. The 
method is acceptable.  
 
5. In the "Method" regarding chance: The authors should present the study power and 
calculate the sample size of the study.  
 
6. The most imp ortant finding in this study was that "lack of endoscopy" was correlated to 
mortality. The authors proposed that hemodynamically unstable and very sickness might 
be the causes of "lack of endoscoy" (lines 20th -22nd, page 13). I suggest the authors to 
make a new table to show the potential factors which may correlate to "lack of 
endoscopy" and to discuss the possible reasons.   
 
7. I suggest the authors to create a composite score according to the four independent risk 
factors to predict mortality in Tanzania . Moreover, to present the Kaplan -Meier survival 
curve for 60 -day mortality by the new composite score instead of current Figure 2 to 5.  
 
8. In the "Discussion", because the mortality rate in this study is higher than the average in 
other studies, I sugges t the authors to address this important issue in Tanzania. Moreover, 
the authors should address the possible method to reduce the high mortality rate. For 
example, to discuss the possible causal -relationship between "lack of endoscopy" and 
"mortality" beca use only this factor has the potential to be corrected. If "lack of 
endoscopy" is a real cause of mortality, undergoing endoscopy has potential to reduce the 
mortality rate. In this way, the authors could answer the study aim, "guide management 
more effici ency".  
 
9. In table 2, please recheck the data of "arterial oxygen saturation (%)" in "yes" and "no" of 
60-day mortality (line 3rd, page 8).  
 
10. In Table 4, the p value of serum creatinine > 115 micromol/L should not be 1.55. Please 
recheck that.  
 
11. I suggest the authors to combine Table 3 and Table 4 to be a new table. Therefore, 
readers could get the results of the univariate and multivariate analyses in a single one.  
 
12. Please re -organize the Table 2 and 3. It is not necessary to duplicate the same or similar 
information in different manners; for example, to present the Rockall score in the manner 
of a continuous variable and a categorical variable, respectively.    
 
Are the methods appropriate and well described?  
If not, please specify what is required in your comments to the authors.  
 
No 
 
Does the work include the necessary controls?  
If not, please specify which controls are required in your comments to the authors.  
 
Yes 
 
Are the conclusions drawn adequately supported by the data shown?  
If not, please explain in your comments to the authors.  
 
Yes 
 
Are you able to assess any statistics in the manuscript or would you recommend an 
additional statistical review?  
If an additional statistical review is recommended, please specify what aspects require further 
assessment in your commen ts to the editors.  
 
I am able to assess the statistics  
 
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Needs some language corrections before being publ ished  
 
Declaration of competing interests  
Please complete a declaration of competing interests, considering the following questions:  
 
1. Have you in the past five years received reimbursements, fees, funding, or salary from an 
organisation that may in any way gain or lose financially from the publication of this 
manuscript, either now or in the future?  
 
2. Do you hold any stocks or shares in an organisation that may in any way gain or lose 
financially from the publication of this manuscript, either now or in the future?  
 
3. Do you hold or are you currently applying for any patents relating to the content of the  
manuscript?  
 
4. Have you received reimbursements, fees, funding, or salary from an organization that 
holds or has applied for patents relating to the content of the manuscript?  
 
5. Do you have any other financial competing interests?  
 
6. Do you have any non-financial competing interests in relation to this paper?  
 
If you can answer no to all of the above, write 'I declare that I have no competing interests' 
below. If your reply is yes to any, please give details below.  
 
I declare that I have no competing interests  
 
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