Mortality in SLE patients compared with population controls in Finland in years 2000-2015

Objective To estimate the risk of mortality in the Finnish incident SLE cohort in a 16-year period compared with the general population. Methods Adults with new-onset SLE between 1 January 2000 and 31 December 2014 identified from the national drug reimbursement register and their individually matched controls from the Population Register Centre were followed up until death or 31 December 2015. Data on deaths were retrieved from the national causes of death register. Comorbidities and education were obtained by linkage to the other national registries. Results A total of 1006 patients with incident SLE and 3005 population controls were found (mean follow-up 8.6years). Of these, 98 SLE patients subsequently died. Their 5 -, 10-, and 15-year survival rates were 95.0% (95% CI: 93.3, 96.2), 88.8% (86.2, 91.0), and 82.1% (77.6, 85.8), respectively. Crude hazard ratio (HR) was 1.61 (95% CI: 1.26, 2.06), adjusted for education level was almost the same 1.61 (95% CI: 1.26, 2.05). After adjustment for comorbidities and education at baseline, the difference in mortality disappeared: HR 1.14 (95% CI: 0.88, 1.48). The leading causes of death were cardiovascular diseases (CVDs) (33%), malignancies (27%) and neurological diseases (10%). Subhazard ratio for CVD deaths was 1.28 (95% CI: 0.85, 1.93), adjusted for comorbidities and education 0.88 (95% CI: 0.56, 1.39). Conclusions These results suggest that the increased mortality in SLE patients is highly associated with comorbidities present at diagnosis. This underlines the importance to screen and treat comorbidities and disease actively without delays.