Association between diarrhea quantity and in-hospital mortality in intensive care unit patients: A retrospective cohort study

Abstract Background Previous studies have shown that diarrhea is associated with increased mortality of patients in intensive care units (ICUs). However, these studies used dichotomized cutoff values, even if diarrhea was a continuous condition. This study aimed to assess the association between diarrhea quantity and mortality in ICU patients with newly developed diarrhea. Methods We conducted this single-center retrospective cohort study at the Kameda Medical Center ICU. We consecutively included all adult ICU patients with newly developed diarrhea in the ICU between January 2017 and December 2018. Newly developed diarrhea was defined based on a Bristol stool chart scale ≥ 6 and frequency of diarrhea ≥ 3 times per day. We excluded patients who already had diarrhea on the day of ICU admission among other criteria. We collected data on the quantity of diarrhea 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 the quantity of diarrhea and mortality were estimated using multivariable-modified Poisson regression models adjusted for the Charlson Comorbidity Index, sequential organ failure assessment score, and serum albumin levels. Results Among 231 participants, 68.4% (158/231) were men; the median age of the patients was 72 years. The median quantity of diarrhea was 401 g (interquartile range [IQR] 230‒645 g), and in-hospital mortality was 22.9% (53/231). More diarrhea at baseline was associated with higher in-hospital mortality; the unadjusted RR (95% CI) per 200-g increase was 1.10 (1.01‒1.19). This association remained in the multivariable-adjusted analysis; the adjusted RR (95% CI) per 200-g increase was 1.10 (1.01‒1.20). Conclusions A greater quantity of diarrhea was an independent risk factor for in-hospital mortality. The quantity of diarrhea may be an indicator of disease severity in ICU patients.