Review for 10.1186/s12876-025-03764-8 (2025)

Title: Association between hematocrit and mortality in critically ill patients with acute
pancreatitis: a retrospective cohort study
Version: 1 Date: 13 Jan 2025
Reviewer:  Anwar Ashraf Abouelnasr
Reviewer's report:
Dear Authors, please address the following points below
-The introduction could be slightly more concise. Some sections could be condensed to avoid
redundancy (e.g., more brief mention of mortality rates in severe AP).
-The explanation of how special treatments or drugs were coded or accounted for in the analysis
could provide more clarity.
-It would be helpful to mention how sensitivity analyses were performed with the raw data,
especially since the dataset had missing values. Providing examples of how results changed with
different imputation strategies could enhance transparency.
-While the use of LOWESS and RCS regression is appropriate, providing a brief rationale
for these choices (e.g., advantages over linear models in clinical research) could improve
accessibility for readers unfamiliar with these statistical tools.
-The results section would benefit from more consistent reporting of median values and
interquartile ranges (IQRs) for HCT. For example, the sentence: "The non-survivor group
exhibited a notable decline in HCT levels compared to the survivor group (33.6 (29.5, 38.1) vs.
32.1 (28.1, 37.4), P < 0.01)" could be more clearly expressed if the numbers were accompanied
by precise information on how these values were calculated (e.g., whether they represent the
mean or median HCT levels, as the text seems to fluctuate between these).
-The difference in HCT levels between survivors and non-survivors would also benefit from
clarification—are these differences in the median values or the mean values? This distinction is
important because the distribution of HCT values might skew the interpretation.
-While the discussion of contrasting studies (i.e., those supporting both high and low HCT
levels as risk factors) is valuable, a deeper exploration of the mechanisms behind these findings
could improve the section. For example, why do some studies associate high HCT with worse
outcomes, while others suggest low HCT is more problematic? What specific factors in AP (e.g.,
systemic inflammation, organ failure, or hemodynamic instability) might mediate these different
effects? Further elaboration on the biological mechanisms underlying these associations could
provide greater clarity and insight.
-While the study highlights the ICU population as a strength, it could further discuss the
unique aspects of this patient group that may make the relationship between HCT and mortality
more pronounced. For instance, the physiological challenges in the ICU setting, such as
hemodynamic instability, fluid management, and multi-organ failure, could explain why HCT
has a stronger prognostic value in this cohort. Exploring these dynamics in more depth would
help contextualize the findings within the ICU environment.
-The U-shaped curve in the findings could be clarified by providing more context on what
constitutes “extremely high” or “low” HCT values. While the text mentions that both high and
low HCT levels are associated with elevated mortality risks, it would be helpful to specify what
HCT ranges correspond to these extremes, based on the findings from the tertile analysis or other
models used. This would help clinicians better understand thresholds for concern.