National epidemiological analysis of lupus in Chile: A registry-based study from 2013 to 2024

Abstract

Background

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease with diverse clinical manifestations and regional variations in epidemiology. Despite its clinical significance, robust epidemiological data from Latin America, particularly Chile, remain limited. This study aims to provide the first comprehensive epidemiological assessment of SLE in Chile using population-adjusted denominators and rigorous statistical methods.

Methods

We analyzed data from Chile’s Specific Health Guarantees Program (GES) from July 2013 to August 2024, covering 95% of the insured population. Population denominators were obtained from Chile’s National Institute of Statistics stratified by age and sex. Incidence rates were calculated using annual new case reports from 2014 to 2023, while prevalence and mortality were estimated through 2024. All analyses included 95% confidence intervals using Poisson distribution methods. Rate ratios were calculated using Poisson regression models with population offset terms. Sensitivity analyses modeled different assumptions regarding program discharge mortality proportions.

Results

The median annual SLE incidence in Chile was 7.1 per 100,000 beneficiaries (IQR 6.3-7.7) using population-adjusted denominators. Prevalence increased from 26.7 per 100,000 in 2013 to 91.3 per 100,000 in 2024. The male-to-female incidence ratio was 1:10.61 (Rate Ratio: 0.093, 95% CI: 0.088-0.098). Mortality analysis using program discharges as a proxy revealed an overall rate of 11.9 per 1000 SLE patients (IQR 7.2-18.8), with significantly higher rates in males compared to females (Rate Ratio: 1.756, 95% CI: 1.546-1.987). Age-stratified analysis demonstrated progressive mortality increases, with patients ≥60 years showing rates of 87.4 per 1000 in males and 49.0 per 1000 in females. Sensitivity analyses modeling different assumptions about discharge mortality (70%-100% fatal) yielded mortality estimates ranging from 8.2 to 11.9 per 1000 SLE patients.

Conclusions

This study provides a comprehensive epidemiological assessment of SLE in Chile using population-adjusted denominators and statistical confidence intervals. Our findings demonstrate SLE incidence rates higher than North American estimates, significant sex disparities in both incidence and mortality, and age-related mortality progression. The sensitivity analysis addresses limitations in mortality estimation through administrative data. These findings contribute essential epidemiological parameters for healthcare planning and underscore the need for enhanced surveillance systems for autoimmune diseases in Latin America.