Abstract / Summary
Abstract Arterial bicarbonate is routinely available, but its association with short-term mortality in acute pancreatitis is uncertain. We retrospectively studied adults with an acute pancreatitis discharge diagnosis and an intensive care unit (ICU) stay in MIMIC-IV version 3.1. The exposure was the first arterial blood gas bicarbonate measured from 6 h before to 24 h after ICU admission. The primary outcome was 30-day mortality. Among 1,280 eligible patients, 1,263 had a bicarbonate measurement and 201 died within 30 days. After adjustment for age, sex, weight, Charlson comorbidity score, and ICU day-1 Sequential Organ Failure Assessment, each 5 mmol/L lower bicarbonate was associated with higher mortality (odds ratio 1.19, 95% confidence interval 1.02–1.40; P = 0.032). Mortality was 22.5% with bicarbonate < 22 mmol/L and 9.5% with bicarbonate ≥ 22 mmol/L; the adjusted odds ratio was 1.73 (1.20–2.49; P = 0.003). The categorical association remained in an enzyme-supported cohort. Lower bicarbonate was associated with higher mortality, but attenuation after severity adjustment and limited incremental model performance suggest that it mainly reflects concurrent critical illness rather than an acute pancreatitis-specific prognostic signal.