Mortality, causes of death and influence of medication use in patients with systemic lupus erythematosus vs matched controls

OBJECTIVES: We wanted to estimate the magnitude of the risk from all-cause, cause-specific and sex-specific mortality in patients with SLE and relative risks compared with matched controls and to evaluate the influence of exposure to medication on risk of mortality in SLE.

METHODS: We conducted a population-based cohort study using the Clinical Practice Research Datalink, Hospital Episode Statistics and national death certificates (from 1987 to 2012). Each SLE patient (n = 4343) was matched with up to six controls (n = 21 780) by age and sex. Cox proportional hazards models were used to estimate overall and cause-specific mortality rate ratios.

RESULTS: Patients with SLE had a 1.8-fold increased mortality rate for all-cause mortality compared with age- and sex-matched subjects [adjusted hazard ratio (HR) = 1.80, 95% CI: 1.57, 2.08]. The HR was highest in patients aged 18-39 years (adjusted HR = 4.87, 95% CI: 1.93, 12.3). Mortality rates were not significantly different between male and female patients. Cumulative glucocorticoid use raised the mortality rate, whereas the HR was reduced by 45% with cumulative low-dose HCQ use. Patients with SLE had increased cause-specific mortality rates for cardiovascular disease, infections, non-infectious respiratory disease and for death attributable to accidents or suicide, whereas the mortality rate for cancer was reduced in comparison to controls.

CONCLUSION: British patients with SLE had a 1.8-fold increased mortality rate compared with the general population. Glucocorticoid use and being diagnosed at a younger age were associated with an increased risk of mortality. HCQ use significantly reduced the mortality rate, but this association was found only in the lowest cumulative dosage exposure group.