Review for 10.1186/s12876-025-03872-5 (2025)

Title: Risk factors for unplanned 31-day readmission after surgery for colorectal cancer Patients:
a meta-analysis
Version: 1 Date: 11 Feb 2025
Reviewer's report:
The manuscript presents a meta-analysis focusing on risk factors associated with unplanned 31-
day readmission after colorectal cancer surgery. The study follows PRISMA guidelines, includes
15 studies, and evaluates 30 risk factors. Statistical analysis was conducted using RevMan 5.4
software, and results are presented through odds ratios (ORs), confidence intervals (CIs), and
p-values.
The study addresses a highly relevant clinical issue, as postoperative readmission is a major
challenge in surgical care, impacting patient outcomes, hospital resource utilization, and
healthcare costs. However, despite its strong methodology and well-organized data presentation,
the study has methodological, statistical, and reporting limitations that must be addressed before
publication.
Scientific Evaluation
Strengths of the Study
The study is clinically relevant, focusing on postoperative readmissions, which are a major
concern in colorectal cancer surgery.
The meta-analysis approach strengthens statistical power by aggregating data from multiple
studies.
The literature search is comprehensive, including multiple databases (PubMed, Embase, Web
of Science, CNKI, SinoMed, VIP Journal Database, and Cochrane Library), ensuring a broad
data pool.
The use of PRISMA guidelines improves methodological transparency.
The study applies appropriate statistical models, using a random-effects model to account for
heterogeneity.
The results are clearly presented, with odds ratios, confidence intervals, and p-values reported
for each analyzed risk factor.
Methodological Review
1. Research Question and Hypothesis
The research objective is clearly defined, as the study aims to identify key risk factors for
unplanned readmission after colorectal cancer surgery.
However, the hypothesis is not explicitly stated. The authors should clarify whether they
expected specific factors to be significant based on prior evidence and why these particular risk
factors were selected for analysis.
2. Study Selection and Risk of Bias
The study claims to follow PRISMA guidelines, but the PRISMA flowchart is missing. The
authors must include a detailed flowchart illustrating the study selection process, reasons for
exclusion, and final included studies.
The risk of bias assessment is not clearly explained. The authors mention methodological quality
assessment in Table 1, but no validated tool (e.g., Newcastle-Ottawa Scale or Cochrane Risk
of Bias tool) is specified. A detailed description of the risk of bias evaluation process must be
included.
3. Inclusion and Exclusion Criteria
The inclusion criteria are briefly mentioned, but they lack specificity.
The exclusion criteria are vague or undefined. Without clear exclusion parameters, there is a
high risk of selection bias, which could compromise the study’s validity.
The authors must explicitly define the eligibility criteria used to select studies for inclusion and
justify any exclusions.
4. Ethical Considerations
The study states that ethics approval was not required, which is reasonable for a meta-analysis.
However, this should be explicitly stated in a dedicated section, referencing relevant guidelines
such as PRISMA or the Cochrane Handbook.
5. Data Extraction and Processing
The data extraction process is well described. Two independent reviewers performed data
collection, with a third author resolving discrepancies. This is a methodologically sound
approach and reduces the risk of bias in data selection.
However, it is unclear whether inter-rater reliability was assessed. The authors should report a
Cohen’s kappa coefficient or inter-observer agreement rate to confirm the consistency of the
extracted data.
Statistical Evaluation
1. Meta-Analysis Model
The study correctly uses a random-effects model, which is appropriate given the heterogeneity
of included studies.
However, there is limited justification for choosing this model. The authors should clarify why
a fixed-effects model was not considered and provide a more detailed explanation of model
selection.
2. Heterogeneity Reporting
The manuscript does not clearly report heterogeneity statistics (I² values), which are essential to
determine whether study results are consistent or highly variable.
High I² values would suggest substantial variability among studies, potentially affecting the
reliability of pooled estimates.
A subgroup analysis should be conducted for factors with high heterogeneity, such as patient
demographics, comorbidities, and hospital characteristics.
3. Publication Bias Analysis
No funnel plot or Egger’s test is presented, making it difficult to assess publication bias.
The authors should include a funnel plot to visually inspect potential bias and report Egger’s
regression test results for further validation.
4. Effect Size and Confidence Intervals
The reported odds ratios (ORs) and confidence intervals (CIs) are well-structured, but their
interpretation needs further expansion in the discussion section.
The authors should contextualize their findings within existing literature, highlighting
agreements, discrepancies, and clinical implications.
5. Potential Confounders Not Addressed
The manuscript does not adequately control for confounding variables, such as socioeconomic
status, hospital volume, or surgeon experience, which can significantly impact readmission rates.
A meta-regression analysis should be considered to explore the impact of these variables.
Results and Data Presentation
1. Tables and Figures
The tables present a clear summary of study characteristics and key findings.
The forest plots in Supplementary Material 3 improve data visualization.
2. Figure Formatting Issues
Some forest plots lack standardized formatting, with inconsistent font sizes and spacing.
Figures should be uniformly formatted for clarity and readability.
Conclusion and Discussion
1. Conclusion Aligns with Results
The conclusion accurately summarizes the study findings, identifying key risk factors for
unplanned readmission.
2. Discussion Section Needs Strengthening
The clinical implications of the findings should be better contextualized, particularly regarding
preventive strategies and hospital interventions.
The limitations section should explicitly discuss:
Potential biases in included studies
Heterogeneity issues
Confounding factors
Limitations in database selection
Final Decision and Recommendations
Decision: Minor Revisions Required Before Acceptance
Necessary Revisions
One, clarify the risk of bias assessment by specifying if the Newcastle-Ottawa Scale or another
validated tool was used.
Two, include a PRISMA flowchart to provide a detailed study selection process.
Three, clearly define inclusion and exclusion criteria to reduce the risk of selection bias.
Four, report heterogeneity statistics (I² values) and conduct a subgroup analysis for highly
variable factors.
Five, include a funnel plot and Egger’s test to assess publication bias.
Six, improve figure formatting to enhance clarity and readability.
Seven, expand the discussion section, incorporating stronger interpretation of findings and
addressing potential confounders.
Final Remarks
The manuscript is well-structured, clinically relevant, and methodologically sound but requires
minor revisions to improve statistical transparency, reporting clarity, and bias assessment.
Once these revisions are made, the manuscript will be ready for publication.
Recommended Decision: Minor Revisions Before Acceptance
Next Step
Authors should address the seven key revisions and resubmit the manuscript for a final review.
Reviewer’s Recommendation
Minor revisions required, likely acceptable after revisions.