Review for 10.1186/s12876-022-02145-9 (2022)

Title: Development and validation of a model to predict rebleeding within three days after
endoscopic hemostasis for high-risk peptic ulcer bleeding
Version: 1 Date: 05 Dec 2021
Reviewer:  Sz-Iuan Shiu
Reviewer's report:
1. Page 4, line 14-18:
The authors wrote an original article to provide nomogram that incorporates factors from clinical
practice to endoscopic features to predict rebleeding rate within three days after emergency
endoscopic hemostasis and identify high-risk patients with peptic ulcer rebleeding sufficiently.
Authors mentioned that many patients die every year due to peptic ulcer rebleeding (PUB),
especially rebleeding within three days after endoscopic hemostasis. According to 2021 ACG
Clinical Guideline (Am J Gastroenterol. 2021; 116: 899-917), mortality was important but not
critical for decision-making because death is uncommon in patients with upper gastrointestinal
bleeding (UGIB) and the references [5-7] didn’t mention that the mortality of PUB was
associated with rebleeding rate within 3 days after hemostasis. Could the authors specify the
latest mortality rate of peptic ulcer rebleeding and the causality between mortality of PUB and
rebleeding rate within 3 days after hemostasis? Why wouldn’t the authors choose morality rate
rather than the rebleeding rate as study outcome?
2. Page 5, line 10-12:
Authors mentioned that shortage of studies predicting rebleeding rate within three days after
endoscopic hemostasis and unsatisfactory ability of existing models to predict clinical prognosis
are two main limitations nowadays. Although one systemic review (Can J Gastroenterol Hepatol.
2014; 28: 543-8) concluded that in high-risk PUB undergoing successful endoscopic hemostasis,
most patients experienced rebleeding within three days, but the correlation between rebleeding
within three days and mortality/morbidity was not well known. Is there any latest evidence to
proof that rebleeding within three days could be a surrogate of mortality or other important
outcomes? In this single center study the morality rate was 33.3% in rebleeding group, which
indicated that the mortality rate and surgery rate were higher than expected in clinical practice.
3. Page 5, line 21-22:
In this study the exclusion criteria included bleeding due to malignancy, Dieulafoy's lesions,
Mallory-Weiss syndrome and so on, and ulcer bleeding around anastomosis after abdominal
surgery was 13.7% within this study. Why didn’t the author exclude patients after abdominal
surgery to minimize selective bias? Is the risk of peptic ulcer rebleeding between patients without
surgery and with surgery similar?
4. Page 6, line 7-9:
In this retrospective cohort study rebleeding was defined as recurrent hematemesis or melena
with a decrease in hemoglobin by at least 2 g/dL within three days after the initial endoscopic
treatment. However, melena after hemostasis could be residual hemoglobin within GI tract as
well as decreasing hemoglobin due to aggressive hydration in clinical practice, which indicated
that second look of endoscopy could be more accurate than above definitions. How did author
avoid measurement bias in these situations?