Increasing rates of hospitalizations with autoimmune hepatitis as the primary discharge diagnosis in Chile: a national analysis from 2001 to 2024

Autoimmune hepatitis (AIH) is a chronic immune-mediated liver disease with limited epidemiological data from Latin America. We aimed to evaluate temporal trends, demographic characteristics, and clinical outcomes of hospitalizations with AIH as the primary discharge diagnosis in Chile between 2001 and 2024. We conducted a nationwide retrospective study using publicly available hospital discharge databases. Hospitalizations with a primary diagnosis of AIH (ICD-10 code K75.4) were identified. Annual rates of hospitalizations with AIH as the primary discharge diagnosis were calculated using national population estimates. Temporal trends were assessed using negative binomial regression. Factors associated with in-hospital mortality were evaluated using multivariable logistic regression. A total of 4,126 hospitalizations with AIH as the primary discharge diagnosis were included. Most hospitalizations occurred in women (79.2%), and the median length of stay was 5 days (interquartile range, 1–12). Overall, in-hospital mortality was 3.6%. Hospitalizations increased markedly over time, from 4 hospitalizations in 2001 to 435 in 2024. Negative binomial regression demonstrated a significant increase in hospitalization rates throughout the study period (incidence rate ratio of 1.13 per year; 95% confidence interval [CI] 1.11–1.16; p < 0.001), corresponding to an average annual increase of 13%. The upward trend persisted in a sensitivity analysis restricted to 2010–2024 (IRR 1.09 per year, 95% CI 1.07–1.11; p < 0.001). In multivariable analysis, older age was independently associated with higher in-hospital mortality, whereas private health insurance was associated with lower mortality risk compared with the public health system. Hospitalizations with AIH as the primary discharge diagnosis in Chile increased substantially between 2001 and 2024, while in-hospital mortality remained low and stable. These findings highlight the increasing healthcare utilization associated with AIH and the importance of continued surveillance of hospitalization trends and optimized disease management strategies.