Review for 10.1186/s12876-023-02746-y (2023)

Title: Early symptoms preceding post-infectious irritable bowel syndrome following
COVID-19: A retrospective observational study incorporating daily gastrointestinal symptoms
Version: 1 Date: 17 Feb 2023
Reviewer's report:
In the last few years, many studies have examined the relationship between SARS-CoV-2
infection and functional gastrointestinal (GI) disorders, especially irritable bowel syndrome
(IBS). However, too few articles were characterized by the use of proper methodology and
appropriate selection of endpoints. I consider some methodological choices in this article to be
inadequate, so the results may not be reliable.
Major revisions:
1. A retrospective study determines the risk of greater bias in selecting the study population. In
lines 149-152, the authors state: “GI symptoms during hospitalization were initially assessed by
a treating physician, and gastroenterologists were consulted as needed. Although GI diseases
can be diagnosed by either a treating physician or gastroenterologist, patients with confirmed or
suspected GI diseases are always assessed by a gastroenterologist”. Patients often underestimate
functional GI symptoms, especially when distracted by the concomitant presence of more serious
clinical conditions, such as COVID-19, for which they required hospitalization. Therefore,
only a careful medical history by a gastroenterologist can detect any functional GI symptoms
promptly. Specifically, the authors state that only patients with GI diseases and not, more
generically, with GI symptoms were evaluated by a gastroenterologist. This may underestimate
the diagnosis of functional GI disorders.
2. Lines 167-168: “Patients who had been diagnosed with IBS before COVID-19 diagnosis
were excluded”. Similarly exclude patients with a previous diagnosis of IBS, is difficult if not
adequately explored, given the wide variability of symptoms.
3. Lines 184-186: “Diarrhea was defined as 6 or 7 on the Bristol scale [19], and constipation was
defined as absence of defecation for 3 consecutive calendar days”. These definitions of diarrhea
and constipation are not complete, as the number of defecations/day and Bristol 1-2 stools were
not considered, respectively.
4. Lines 186-194. How did you manage to guarantee a period of observation of symptoms of
at least 3 months if you state that the post-discharge follow-up was variable between 1 month
to 1 year? Patient data during hospitalization was taken from the Donner Registry, but after
discharge how did you get it? Were the Rome IV criteria used to diagnose IBS? The diagnosis
of IBS cannot be confirmed by the use of medication for IBS, as there are no specific therapies.
Furthermore, 3 months of therapy for IBS with at least a 1-month interval before symptom onset
is equivalent to an observation period of 2 months, insufficient for the Rome IV criteria.
5. Table 2 identifies the subtypes of IBS according to the therapies taken. To distinguish the
different subtypes of IBS the Rome IV criteria must be used, also because the therapies can be
variously used.
Minor revisions:
1. Lines 181-182: “Daily GI symptoms during hospital stay were recorded by healthcare
providers at least three times a day…”. Is this a normal clinical practice in your center? Which
healthcare providers were involved?