Review for 10.1186/s12876-020-01443-4 (2020)

Reviewer’ s report
Title: A Retrospective Study on the Association of Gastrointestinal Symptoms in Children with
Low Lactase Activity and Low Activity of Other Disaccharidases
Version: 1Date: 07 Jun 2020
Reviewer's report:
This is a potentially interesting study but unfortunately its retrospective nature deeply affects the
the authors'conclusions. So I have some doubts whether this manuscript represents a scientificallysound contribution to the field.
ABSTRACT
-"To explore the association of low activity of disaccharidase and combinations of lowdisaccharidases with.." do the authors mean "combination of low activity of differentdisaccharidases"??- "…children 0-21 yrs.".. but 21 years old are young adults. The authors should specify also in theabstract-"Children with low pandisaccharidase (all four tested enzymes) may be correlated with abdominalpain and have a unique frequency of GI symptoms…." The meaning is quite obscure, the authorsshould clarify
-"reflux" better "Gastroesophageal Reflux"
RESULTS-page 8 line 23: "weigh loss" > weight loss
-Page 9 lines 13-14: "with the absence weight loss" probably absence of weight…
-"Subjects with low pandisaccharidase (all four tested enzymes) activity may be correlated with
increased frequency of abdominal pain compared to subjects with normal enzyme activity for alldisaccharidases, but this difference was not statistically significant": if the result was notstatistically significant why do the authors write "may be correlated". Is there trend toward a acorrelation?
-"Of the 347 subjects, 209 (60%) had reactive epithelial changes in the distal esophagus, 34
(10%)"Did the authors perform also esophageal biopsies? In methods there is no evidence.
DISCUSSION
-The authors should explain what's the reason to publish nowadays a retrospective casuistry ofeight years ago.. probably the paper by Chumpitazi et al.?
-page 10 lines 9-10 "…palatinase activity. And low pandisaccharidase activity may be associated
with a unique pattern of GI symptoms" The punctuation should be changed but what is the
meaning? In the abstract the authors write "Low pandisaccharidase activity was not significantly
associated with any GI symptom".
-page11 Lines 3-7 "Subjects with low pandisaccharidase activity may be correlated to higher
frequency of abdominal pain (87.5%), but interestingly, lower frequency of diarrhea (12.5%),reflux (12.5%), and weight loss (0%) compared to subjects with all normal disaccharidase activity(Table 3). This observation appeared to be unique, however, statistical significance was notachieved, likely due to inadequate sample size." The observation is quite odd but if statisticalsignificance was not achieved how did the authors justify their statement?
-page 11 lines 11-14 "Additionally, we suspected that the frequencies of GI symptoms in subjects
with only low lactase activity may be different from the frequencies in subjects lowpandisaccharidase activity, but this also was not statistically significant" As above: the statementseems not to be justified by statistical analysis.
Pag.12 lines 7-8 "….we found chronic duodenitis to be associated with low lactase with low
alpha-glucosidases" probably "and low alpha-glucosidases"
Pag. 12 lines 12-13: "In our study, we did not find any association with lactase alone, but with
lactase in combination with other disaccharidases which has not been examined" probably"lactase…other disaccharidases deficiencies"?
Pag. 12 lines 19-20 "…low activity of an enzyme is not equal to a clinical enzyme deficiency" do
the authors mean that low activity is not automatically related to clinical manifestions?
Are the methods appropriate and well described?
If not, please specify what is required in your comments to the authors.
NoDoes the work include the necessary controls?
If not, please specify which controls are required in your comments to the authors.
Unable to assessAre the conclusions drawn adequately supported by the data shown?
If not, please explain in your comments to the authors.
NoAre 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 furtherassessment 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:
Needs some language corrections before being publishedDeclaration 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
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