Extreme temperature events and hospitalizations for 59 autoimmune diseases in Korea: A nationwide outcome-wide, time-stratified, case-crossover study

초록

Extreme temperature events are increasing in frequency and intensity, yet their effects on autoimmune diseases remain poorly understood. Using nationwide inpatient claims from the Korean National Health Insurance Service (2002 -2023), we assessed short-term associations between extreme temperatures and hospitalizations for 59 autoimmune conditions. A time-stratified case-crossover design with conditional logistic regression was applied. Heat waves and cold spells were defined using district-specific temperature percentiles (95th, 97.5th, and 99th for heat; 5th, 2.5th, and 1st for cold) and single-day and consecutive exposures (2–3 days). Multiple testing used the Benjamini–Hochberg false-discovery rate. For FDR-significant outcomes (inflammatory bowel disease and Crohn's disease), subgroup analyses evaluated heterogeneity by sex, income level, and urbanicity with Wald tests of effect modification. Among 536,485 autoimmune disease–related hospitalization events, heat waves were more consistently associated with an increased risk of hospitalization compared with cold spells, with stronger associations at higher percentiles and with 2–3 consecutive days of exposure. The strongest associations were observed for gastrointestinal autoimmune conditions, with effect estimates progressively strengthening across higher percentile thresholds and longer durations. Three consecutive days of heat-wave exposure at the 95th and 97.5th percentile were associated with increased hospitalizations for inflammatory bowel disease (OR = 1.13 at both thresholds; 95% CI, 1.06–1.21 and 1.05–1.22) and its Crohn's disease subtype (OR = 1.15 at 95th and 1.17 at 97.5th; 95% CI, 1.05–1.25 and 1.07–1.29), both retaining significance after FDR correction. For inflammatory bowel disease and Crohn's disease, heat-related associations appeared larger in men, those younger than 65, low- and middle-income groups, and non-metropolitan residents, although formal interaction tests did not reach statistical significance. These findings identify autoimmune diseases, particularly inflammatory bowel disease subtypes, as potentially temperature-sensitive outcomes warranting confirmation in independent cohorts and further mechanistic investigation.

키워드