Review for 10.1186/s12876-023-02972-4 (2023)

Title: Acute pancreatitis in intraductal papillary mucinous neoplasm: A single-center
retrospective cohort study with systematic review and meta-analysis
Version: 3 Date: 23 Apr 2023
Reviewer's report:
Reviewer’s comments for the authors:
The authors have performed a single-center retrospective cohort analysis on patients with IPMN,
evaluating the association between acute pancreatitis (AP) and various clinical features of the
analyzed population, radiological and pathological characteristics of the tumor, and also disease
prognosis. They are also reporting the diagnostic capacity of various high-risk features of IPMN,
including AP development for high-grade dysplasia, invasive cancer, and intestinal type IPMN
respectively. Moreover, they performed a systematic review and meta-analysis on the same
topic which they reported together with the cohort analysis. The subject is of great interest and
the paper is structured coherently and well-balanced. The authors may consider addressing the
following aspects:
Major comments:
Methods:
- Regarding the cohort analysis:
# it would increase the clarity of the paper if the authors defined their outcomes in the methods
sections
- Regarding the systematic review and meta-analysis:
#  Was the protocol for the study pre-recorded on   PROSPERO (1)? If so, please mention the
CRD if not, please state; if not recorded, this could also be considered among the limitations
of the study
# On the systematic search – if the date of the search was January 2021, there is a great chance
several other eligible papers have been published in the past 2 years – the authors may consider
updating the search; if more eligible papers are identified and included in the analysis, the
limitation of the low number of available studies for meta-analysis will be addressed; moreover,
the authors will be providing an up-to-date summary of the available data in the literature on the
topic;  were there any restrictions of filters at all applied in the systematic search?
# On exclusion criteria: regarding reports of overlapping populations – could the authors identify
them and cite them - and explain how they decided which of the available reports to include in
the analysis?; also could the authors explain more clearly what ‘incomplete data’ refers to?
# On data extraction: could the authors describe the study selection process – what tools were
used? was it performed in a stepwise manner -First based on the title and abstract and afterwards
based on full-text contents? Have the authors evaluated the agreement between the authors
selecting the eligible reports – e.g. was Cohen’s kappa calculated? If yes, it should be reported;
# On study quality evaluation: the authors may consider adding as supplementary material the
detailed criteria applied for using the NOS; i.e. – in terms of selection: what was considered
a truly representative population and a secured record; what confounders were considered for
comparability; what was considered long enough in terms of follow-up for outcome assessment;
was quality evaluation also performed in pairs or by an independent author?
Results:
- The authors may consider following the STROBE guidelines in presenting the results of the
cohort analysis and the PRISMA guidelines for the systematic review and meta-analysis (2,3)
- Regarding the cohort analysis
# On postoperative follow-up: it would be interesting to see the distribution of indications for
surgery in each  group (summarized also in Supplementary Table 1);
- Regarding the systematic review and meta-analysis:
# The authors claim to have included 10 studies in the systematic review and 5 in the metanalysis;
the qualitative synthesis of the systematic review is completely missing; the remaining 5 studies
ineligible for meta-analysis should be cited, included in table 5 and a qualitative summary of
their findings should be included in the results section
# Have the authors considered performing the meta-analysis including also their results?
although these are not yet peer-reviewed results, it may be interesting to include them at least in
the supplementary material – this way also the latest paper on the topic is included in the analysis;
Discussion:
- The authors may consider summarizing also the implications of their findings
Minor comments:
Abstract:
- the authors are reporting results (number of patients and age) in the methods section; they
should be kept in the results section
Methods:
- Regarding the systematic review and meta-analysis:
# On the systematic search: in the search terms one parathesis – ( may be missing before “IPMN”
# On the inclusion criteria: the authors may also consider the PECO (population, exposure,
comparison, outcome) framework to define them and formulate their clinical question – P:
patients with IPMN, E – AP group; C – non-AP group; O: enumerate the outcomes; this could
furthermore enhance clarity; regarding the diagnosis of AP and IPMN the authors should cite
the guidelines considered authoritative in this regard;
# On statistical analysis: what was considered a small number of studies for meta-analysis? Also,
in calculating the pooled results -  have the authors used the unadjusted or the adjusted ORs and
95%CIs reported across the eligible articles?
Results:
- Regarding the cohort analysis:
# On clinical data: in the first paragraph, third phrase  - the authors should mention in which of
the groups smoking and hypertension is more prevalent – although the information in the text
and tables and figures should not be duplicated, each should be standing alone;
# On the association between AP and the evaluated pathological characteristics of the IPMNs –
could the authors mention what kind of samples were used for evaluation – biopsy of surgical
specimens?
# On postoperative follow-up -  how was insufficient secretion defined?
1. https://www.crd.york.ac.uk/prospero/
2. https://www.equator-network.org/reporting-guidelines/strobe/
3. http://prisma-statement.org/