Background Systemic lupus erythematosus (SLE) has been associated with an increased mortality rate. However, population-based data on all-cause, age-specific and sex-specific mortality risk are limited and data on the influence of medication exposure on mortality risk in SLE are scarce.
Objectives To estimate the magnitude of the risk from all-cause, age-specific, and sex-specific mortality in patients with SLE and relative risks compared with matched controls, and to evaluate the influence of medication exposure on mortality risk in SLE.
Methods We conducted a population-based cohort study using the Clinical Practice Research Datalink (from 1987 to 2012). Each SLE patient (n=4356) was matched with up to 6 controls (n=21845) by age and sex. Multivariate Cox regression analysis estimated adjusted relative rates (RR) of mortality, and time interaction terms to evaluate mortality timing patterns. Time-dependent Cox models were used to evaluate the association of glucocorticoid use and hydroxychloroquine use on mortality and were adjusted for age, sex, lifestyle parameters, comorbidities and comedication.
Results A total of 442 out of 4356 SLE patients died during the study period. Patients with SLE had an increased mortality rate for all-cause mortality compared with age- and sex-matched subjects, after adjustment for confounders (adjusted RR 1.80, 95% CI 1.57–2.08). Glucocorticoid use in the previous six months raised the mortality rate while the adjusted RR was 45% decreased with low dose hydroxychloroquine use. The RR was highest in patients aged 18–39 years (adjusted RR 4.87, 95% CI 1.93–12.3) and slightly higher in females (adjusted RR 1.82, 95% CI 1.56–2.13) compared to male patients (adjusted RR 1.68, 95% CI 1.19–2.39). The mortality rate was significantly increased for patients with a history of dementia, seizures, diabetes, cancer, and renal disease (Table 1).
Conclusions Patients with SLE have a 1.8-fold increased mortality rate compared with the general population. Glucococorticoid use, female sex and young age are associated with an increased mortality risk while low dose hydroxychloroquine use significantly reduces the mortality rate. In addition, special attention should be paid to lupus patients with neuropsychiatric complications, diabetes, malignancy or renal disease since these subgroups of patients are at high risk of death.
Disclosure of Interest I. Bultink Grant/research support from: Lilly Netherlands, MSD, Amgen, UCB, A. Lalmohamed: None declared, F. de Vries: None declared