Review for 10.1186/s12876-025-04172-8 (2025)

Title: Relationship of Coffee Consumption with Colonic Diverticulosis
Version: 2 Date: 18 Mar 2025
Reviewer's report:
While the study includes a large sample size and attempts to analyze different coffee subtypes,
its methodology and interpretation of findings are inadequate. The study does not provide
meaningful new insights into the relationship between coffee consumption and diverticulosis.
The lack of questionnaire validation, the omission of key risk factors (meat intake, comorbidities,
family history), and the potential underestimation of diverticulosis prevalence due to patient
exclusion criteria significantly weaken the study’s reliability.
Please find attached detailed analysis:
1. Methodological Limitations
o The study relies on self-reported questionnaire data, making it declarative rather than objective.
The study lacks details on the questionnaire’s validation.
o Dietary fiber intake, a well-established factor in diverticulosis development, was not
considered. Omitting this variable weakens the study’s conclusions.
o The study does not consider meat consumption, which is a known dietary risk factor for
diverticulosis. The omission of this variable weakens the analysis of dietary influences.
o Other comorbidities and family history of diverticulosis were not analyzed. Given that
diverticulosis has a strong genetic component, failing to include this information limits the
study’s ability to assess true risk factors.
o The potential influence of other caffeinated beverages (e.g., energy drinks, green tea) was not
accounted for, which could lead to confounding.
o The study does not establish causation—whether coffee consumption influences diverticulosis
or whether individuals with diverticulosis simply have different dietary habits remains unclear.
2. Inadequate Statistical Analysis
o The univariate analysis suggests a protective effect of instant coffee (Nescafe) against
diverticulosis. However, this association disappears in the multivariate analysis, which should
be the primary basis for drawing conclusions.
o The study does not explore possible interactions between variables—for example, older age
is associated with different dietary habits, which were not adequately addressed.
3. Potential Measurement Bias Leading to Underestimation of Diverticulosis Prevalence
o The study reports a diverticulosis prevalence of 9%, which is lower than expected in the general
population, particularly for an endoscopy-based study.
o This low prevalence may result from a methodological error: patients with inadequate bowel
preparation were excluded from the study. However, it is well known that patients with
diverticulosis tend to have poorer bowel cleansing before colonoscopy. This introduces a risk
of type II error (false negative findings), meaning that the true prevalence of diverticulosis in
the study population may be higher than reported.
4. Lack of Clinical Relevance
o Even if instant coffee consumption were protective, the observed difference (0.58 vs. 0.33
cups per day) is minimal and lacks clinical significance.
5. Overstated Conclusions
o The authors suggest that instant coffee has a protective effect, despite this finding not being
significant in multivariate analysis. Such conclusions are misleading and not scientifically
justified.