Review for 10.1186/s12876-015-0353-8 (2015)

Reviewer’s report  
 
Title: Trends in upper gastrointestinal diagnosis over four decades in Lusaka, Zambia: a  
retrospective analysis of endoscopic findings  
 
Version: 0 Date: 15 Jul 2015  
 
Reviewer: Wai-Kit Lo  
 
Reviewer's report:  
 
The authors present a well -written descriptive analysis of retrospective endoscopic data from a 
single endoscopy unit in Lusaka, Zambia, from 1977 -2014, to examine diagnostic trends in GI 
disorders, driven by a dearth of longitudinal medical data from developing countries in Africa.  
This is largely a hypothesis -seeking study, to demonstrate that their database allows for 
assessment of local disease processes and epidemiology, as well as comparison against national 
or international trends.  The procedure under study appears to be limit ed to upper endoscopy, 
with careful review and coding of endoscopic findings, indications for the study, and the 
endoscopist performing the procedure, as well as biopsy results.  
 
Strengths of the study include a wealth of information from almost 17,000 pat ients covering a 38 
year period.  This information could be extremely useful to public health researchers interested 
in examining trends in GI diagnosis in a developing country.  
 
Weaknesses of the study include a question of generalizability, given that th e data arises from a 
single hospital site.  The authors take extra care in comparing their findings with known trends in 
regional and national diagnoses, such as HIV and Shistosomiasis, which helps to address this 
concern.  Additionally, the limitations of  retrospective longitudinal analysis, including increased 
awareness of certain diagnoses, advances in technology, or improved access to care, could 
explain the changes in endoscopic diagnoses over time, but these limitations are not addressed.  
 
Specific qu estions:   
 
- Page 5, Line 59:  Please clarify here what age group is classified as "children."  (I see that it 
is mentioned later on page 8).  
 
- Page 6, Line 6:  What explains the variability in number of procedures performed by doctors, 
and why did some docto rs contribute so few?  Are there any visiting physicians or trainees 
which could have had an impact on diagnosis?  
 
- Page 6, Line 42:  Was there any data on H.pylori infection in peptic ulcer?  
 
- I would suggest a clear discussion of possible limitations, suc h as changes in equipment, 
training, or access to care that may have had an impact on the results over time.  
 
- Why was no data available in 1986?  
- In Table 1, please clarify the significance of the p -values.  What is being compared here?  
Because the last "d ecade" is only 8 years, I do not think this is a meaningful comparison, and 
p-values are not necessary to demonstrate that there are changes over time.  
 
Are the methods appropriate and well described?  
If not, please specify what is required in your comment s to the authors.  
Yes 
 
Does the work include the necessary controls?  
If not, please specify which controls are required in your comments to the authors.  
 
Unable to assess  
 
Are the conclusions drawn adequately supported by the data shown?  
If not, please exp lain 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 comments to the editors.  
 
I am able to assess the statistics  
 
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Acceptable  
 
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