Article Text
Abstract
Background and aims Hospitalisation for Systemic Lupus Erythematosus (SLE) is a significant event. We aimed to understand the factors leading to an incident admission and its impact on long term outcome in SLE patients in Western Australia (WA).
Methods Using whole-population data linkage of hospital admissions, cancer registrations and death records in WA from 1980 to 2015, we performed a retrospective comparative analysis for all patients admitted with a first ever primary diagnosis of SLE (ICD-9-CM 695.4, 710.0, ICD-10-AM L93.0 and M32). For SLE patients, we analysed annual incident hospitalisation rates and compared patient characteristics, all-cause mortality and cancer risk (by Kaplan-Meier and Cox regression) versus age- and gender-matched controls free of rheumatic disease.
Results The incident hospitalisation rate for SLE (mean 20.9/million/year (CI: 11–35) showed little variation. SLE patients were younger, more likely to be Indigenous, uninsured, have kidney and cardiovascular disorders and to die during their first hospitalisation (Table 1). Cancer risk was equivalent, but a first admission for SLE doubled the risk of subsequent death (OR=1.99, CI: 1.5–2.7, p<0.001) (Figure 1, Table 2). Medicare reliance (OR 1.7, CI: 1.4–1.9, p=0.001) and male gender (OR 1.4, CI: 1.0–1.8, p<0.04) were the strongest independent predictors of death.
Patient Characteristics (at incident SLE hospitalisation) and study outcomes.
Kalpan-Meier survival analysis of all-cause motality for SLE patients and age- and sex- matched controls (free of rheumatic disease) from index hospitalisation.
Kalpan-Meier survival analysis of cancer outcomes for SLE patients and age- & sex-matched controls (free of rheumatic disease conditions) from incident hospitalisation.
Cox Regression analysis results for mortality risk factors in SLE patients with incident hospital admissions compared to controls.
Conclusions Hospitalisation rates for SLE in WA have not decreased over 25 years. Once hospital-based management for SLE was required, the risk of all-cause mortality doubled compared to age and gender-matched controls. This risk was greatest in Medicare reliant or male SLE patients and not due to increased cancer risk.