Review for 10.1186/s12876-022-02342-6 (2022)

Title: Increased prescriptions for irritable bowel syndrome after the 2018 Japan Floods: a
longitudinal analysis based on the Japanese National Database of Health Insurance Claims and
Specific Health Checkups
Version: 0 Date: 05 Dec 2021
Reviewer:  Yusuke Kajimoto
Reviewer's report:
The paper is written very well. There are specific points needed to clarify and consider.
Major comments
1. The authors categorized the subjects by IBS drug status on the NDB into "non-users" and
"pre-disaster users.". However, there are people having no record on the NDB in which people
did not receive any medical care for one year before the disaster. The proportion of people would
majorly affects the proportion of IBS drug uses and the trends. The Author would extract the
subject records by area on the NDB. Government/local statistics will provide the population of
the area. For the victims, the Damage  ledger, “Risai Daicho” available? If it available, the data
will be informative for the results.
2.  As the authors mentioned, socioeconomic status is a considered reason for difference of using
IBM. I can agree with the author on that point. however, if so, I consider that the victims have
better access medical access before the disaster, and after the disaster as well. People who have
medical access will more frequently receive  the drugs than people who receives fewer medical
care. And did the physicians already prescribe more IBS drug for victims than non-victims? The
medical access and current tendency of prescription for victims should be discussed.
3. When number of pre-disaster users are 285 subjects of victims on the Table 1, about less than
3.5% on the table 2 indicates less than 10 patients which is prohibited to publish by MHLW not
to identify individuals. Is it allowed by MHLW?
Minor comments
- introduction
1. The reference 14 did not show correlation between IBS and earthquake nor QOL related items.
Correlation between earthquake and QOL related items was shown. Not appropriate reference.
2. The reference 15 is about QOL research. Is it correct? The reference did not mention dementia
among IBS patients over fifty years old.
3. The authors mentioned "Thus, a change of the prescription rate for these drugs is considered
to reflect the change of incidence and prevalence of IBS among the population.". However,
potential IBS patients who has symptoms but not received IBS drug can newly start the drug
treatment. In the case, IBS prescription cannot reflect its incidence.
4. Please provide the references for the Japan floods.
5. Last sentence of the introduction. IBS symptoms cannot be shown from the NDB.
- Methods
1. IBS drugs were ramosetron, polycarbophil calcium, and mepenzolate bromide in this study.
Linaclotide has indication for IBS. Why not included it? if it used even a little, should be
included. Ramosetron can be used for nausea and vomiting caused by anti-cancer treatment. Did
you exclude them by dose or commercial name on the NDB? Please mention it on the article.
2. The NDB is usually abbreviation of The Japanese National Database of Health Insurance
Claims and Specific Health Checkups.
3. Does the public income support mean Public Assistance on Public Assistance Act? Patients
receive public assistance has no co-payment, but is it excluded on medical claims?
4. The author mentions "The rate was calculated by dividing the number of prescriptions for
target drugs by the number of target subjects in a month.". Are there no patients who received
2 or more target drugs in same month?
5. "If IBS drugs were prescribed more than once in a month, it was counted as one prescription.
"means  "Patient who received IBS drugs more than once in a month was counted as one
prescription.”?  It is a primary point, better to clarify the definition.
6. "while the individual analysis was conducted to evaluate the risk for occurrence of prescription
because the time series changes cannot be evaluated among non-users. " is not clear. Why time
series changes cannot be evaluated among non-users? And why is it the reason for conducting
to evaluate the risk for occurrence as individual analysis?
- Results
What is the reason to exclude subjects of difference between 6,176,299 on the NDB and
5,287,888. Please clarify.
- Discussion
The authors consider that one of the reason for increasing  the incidence of IBS was infection.
Number of patients who had colitis increased after the disaster as a disease name on the NDB?
The data is included in the NDB.
- Table 1
in footnote, "Those who had no history of IBS drugs use before the disaster." is better to clarify
it for one year before the disaster.