Short-Term Impact of Fine Particulate Matter on Hepatic Decompensation in Cirrhosis: A Nationwide Case-Crossover Study.

BACKGROUND/AIMS: Cirrhosis is a leading cause of morbidity and mortality, and acute decompensation represents a pivotal event in its natural history. While long-term exposure to air pollution has been associated with liver disease progression, evidence on short-term effects remains limited. We investigated whether daily fluctuations in fine particulate matter (PM2.5) trigger acute decompensation in patients with cirrhosis. METHODS: We conducted a nationwide, time-stratified case-crossover study using the Korean National Health Insurance Service database. Adults with cirrhosis from 2006 to 2021 were included. Emergency department (ED) visits for decompensation, including ascites, variceal bleeding, hepatic encephalopathy, jaundice, or hepatorenal syndrome, served as case days. Control days were matched (same month and weekday). Daily PM2.5 concentrations were assigned to residential districts using a 1-km grid. Conditional logistic regression was used to estimate odds ratios (ORs), adjusting for temperature, humidity, holidays, and weekday/weekend. RESULTS: We analyzed 29,167 patients with cirrhosis (mean age, 59.9 years; 73.1% male) who presented to the ED with hepatic decompensation. Each interquartile range increase in PM2.5 was associated with a higher risk of decompensation (adjusted OR, 1.02; 95% confidence interval, 1.00 to 1.04). Participants in the highest exposure quintile had 5% higher odds of decompensation than those in the lowest quintile. Lagged exposure analyses indicated attenuation of associations with longer averaging windows. Subgroup analyses revealed no significant interactions. CONCLUSIONS: Short-term elevations in ambient PM2.5 levels were associated with an increased risk of acute hepatic decompensation requiring ED visits. Notably, daily air quality fluctuations may contribute to clinically significant events in this vulnerable population.