Mortality in systemic lupus erythematosus in the United Kingdom 1999-2012

Abstract

Objectives. To estimate the mortality associated with SLE during the period 1999-2012 by age, gender and region; and to ascertain the cause of death for people with SLE. Methods. A retrospective cohort study using the UK Clinical Practice Research Datalink. Incident SLE cases diagnosed between 1999 and 2012 were matched by age, sex and practice to four controls. Age-, gender- and region-specific mortality rates were calculated per 1000 person-years and compared with control mortality rates using mortality rate ratios (MRRs). For individuals with linked Office of National Statistics data, cause of death was summarized by International Classification of Disease-10 chapter heading. Results. Of 2740 incident cases, 227 died, giving a mortality rate of 15.84/1000 person-years (95% CI 13.91, 18.04). This was 67% higher than in controls (MRR 1.67, 95% CI 1.43, 1.94, P<0.001). Men with SLE had higher rates of mortality than females with SLE. Compared with controls, the mortality rate for males with SLE was 1.80 times that of male controls (95% CI 1.32, 2.45, P<0.001); for females the mortality rate was 1.64 times higher (95% CI 1.37, 1.96, P<0.001). The age-specific mortality rates increased significantly with age; however, the MRR diminished from 3.81 (95% CI 1.43, 10.14) in those aged<40 years to 0.82 (95% CI 0.36, 1.83) in those ≥ 90 years. There was no significant difference in mortality between regions. Circulatory system disease and malignancy were the most frequent causes of death in both cases and controls. Conclusion. There remains an increased mortality for people with SLE compared with matched controls, particularly at younger ages.