Review for 10.1186/s12876-020-01261-8 (2020)

Reviewer’s report
Title: Gastroesophageal reflux disease in a typical African population A symptom-based multicenter
study.
Version: 1 Date: 01 Jan 2019
Reviewer: Siavosh Nasseri-Moghaddam
Reviewer's report:
Dear Editor
Thank you or sending me this paper for review. The topic is a long awaited one, GERD prevalence in
an African country. The authors have done a very good and systematic job in obtaining their data from
different parts of the big and diversely populated country and should be congratulated on that. Overall
the paper is fine and there is no major problem with it. The following are my suggestions for its
improvemment:
1) The "Introduction" is better to be shortened and some redundant and unnecessary information being
omitted from it.
2) The data presented in the tables are better to be elaborated somewhat more in the "Results" section",
especially the multivariable regression.
3) Some more information on the details and rational for the multivariable regression analysis is needed
in the "Methods" section.
4) There is good information on epidemiology of GERD from middle-eastern countries and the Persian
gulf region which is better to be referred to in this paper and comparisonsbe made with them. Some
good papers are as follows:
    Arch Iran Med. 2007 Jul;10(3):289-94   Nouraie et al
    Am J Gastroenterol. 2007 Jul;102(7):1353-60
    Turk J Gastroenterol. 2012 Aug;23(4):323-32.
    Turk J Gastroenterol 2017; 28(Suppl 1): S1-S2
    J Clin Med Res. 2018 Mar; 10(3): 221-225
5) An interesting finding in this work is that farmers had a higher risk of GERD. Nitrogen fertilizers are
progressively used for improvement of farming crops and fruit and this has led to higher and higher
contents  of nitrates  in the drinking water and vegetables and edible roots  (J  Environ Qual 2014
May;43(3):895-907).  There  are  some  information  linking  high  nitrate  content  of  water  to  higher
prevalence of GER (Arch Iran Med 2011;14(5):312-14). In addition, it has been shown that high nitrate
in rat's diet exposes them to esophageal injury (Scand J Gastroenterol, 2009; 44: 527-537) and human
data for this link is also available (Dig Dis Sci (2012) 57:413-418). The authors can use these data to
explain the finding of higher GERD prevalence among farmers alongside with their other explanations.
Are the methods appropriate and well described?
If not, please specify what is required in your comments 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 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 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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