Onset age affects mortality and renal outcome of female systemic lupus erythematosus patients: a nationwide population-based study in Taiwan.

OBJECTIVE: The objective of this study was to investigate the impact of disease onset age on mortality and renal survival in female SLE patients.

METHODS: This nationwide, population-based, retrospective cohort study used data from the National Health Insurance Research Database of Taiwan. Female patients newly diagnosed with SLE from 2001 to 2004 were identified as the study cohort. A non-SLE group was matched for age, sex and initial diagnosis date (index date) as the comparison cohort. Co-morbidities, mortality rates and end-stage renal disease (ESRD) incidences were compared among SLE patients of different onset age. Hazard ratios with a 95% CI were determined by the Cox proportional hazard model to quantify the mortality rates and ESRD incidences. Juvenile-onset, adult-onset and late-onset SLE patients were categorized according to disease onset age: <18, 18-50 and >50 years old.

RESULTS: In total, 513 juvenile-onset, 3076 adult-onset and 764 late-onset SLE patients were identified. Compared with non-SLE controls, the hazard ratios of mortality were 6.49 (95% CI 3.73, 11.32, P < 0.001) for juvenile-onset, 1.75 (95% CI 1.47, 2.08, P < 0.001) for adult-onset and 3.44 (95% CI 2.76, 4.28, P < 0.001) for late-onset SLE patients. The hazard ratios of incident ESRD were 20.28 (95% CI 12.79, 32.15, P < 0.001) for adult-onset lupus patients and 1.99 (95% CI 1.36, 2.93, P < 0.001) for late-onset patients.

CONCLUSION: Female patients with late-onset SLE carried a higher risk of mortality than those with adult-onset disease in the presence of co-morbidities. Juvenile-onset SLE patients were at greatest risk of mortality, which is probably due to disease severity.