Dose-response Relationship Between Diarrhea Quantity and Mortality in Critical Care Patients: A Retrospective Cohort Study

Background: Previous studies have shown that diarrhea, defined as a dichotomized cutoff, is associated with increased mortality of patients in intensive care units (ICUs). This study aimed to examine the dose-response relationship between the quantity of diarrhea and mortality in ICU patients with newly developed diarrhea.

Methods: We conducted this single-center retrospective cohort study. We consecutively included all adult patients with newly developed diarrhea in the ICU between January 2017 and December 2018. Newly developed diarrhea was defined according to the World Health Organization definition. The consistency of diarrhea was evaluated by the Bristol stool chart scale, and the quantity of diarrhea was assessed on the day when patients newly developed diarrhea. The primary outcome was in-hospital mortality. The risk ratio (RR) and 95% confidence interval (CI) for the association between diarrhea quantity and mortality were estimated using multivariable modified Poisson regression models.

Results: Among the 231 participants, 68.4% were men; the median age was 72 years. The median diarrhea quantity was 401g (interquartile range [IQR] 230‒645g), and in-hospital mortality was 22.9%. More diarrhea at baseline was associated with higher in-hospital mortality; the adjusted RR (95% CI) per 200-g increase was 1.10 (1.01‒1.20), p = 0.029. In sensitivity analyses with near quartile categories of diarrhea quantity (<250g, 250-399g, 400-649g, ≥650g), the adjusted RRs for each respective category were 1.00 (reference), 1.02 (0.51-2.04), 1.29 (0.69-2.43), and 1.77 (0.99-3.21), p for trend = 0.033.

Conclusions: A greater quantity of diarrhea was an independent risk factor for in-hospital mortality. The diarrhea quantity may be an indicator of disease severity in ICU patients.