The risk of cardiovascular morbidity and cardiovascular mortality in systemic lupus erythematosus and lupus nephritis: a Danish nationwide population-based cohort study

Objective. To assess the role of LN as a risk factor for myocardial infarction (MI), stroke and cardiovascular mortality (CVM) in patients with SLE. Methods. The study was conducted using individual-level data from multiple nationwide registers. We identified a cohort of patients diagnosed with SLE and further determined if they had a diagnosis of LN during 1995-2011. Each SLE patient was matched with five population controls. Hazard ratios (HRs) were calculated to measure the risk of MI, stroke and CVM in SLE patients relative to population controls and in SLE patients with relative to without LN. Results. We identified 1644 SLE patients with incident SLE; 233 of these patients had a diagnosis of incident LN during follow-up. The number of events in the SLE cohort was: 42 (MI), 74 (stroke) and 56 (CVM). For MI, the HR was 2.2 (95% CI: 1.4, 3.4) in SLE without LN and 18.3 (95% CI: 5.1, 65) in SLE with LN. The HR for LN was 8.5 (95% CI: 2.2, 33; P = 0.002). For stroke, HRs were 2.1 (95% CI: 1.5, 2.9) and 4.1 (95% CI: 1.9, 8.7) in SLE without and with LN, respectively, and we found no significant association with LN (P = 0.115). For CVM, the respective HRs were 1.6 (95% CI: 1.1, 2.4) and 7.8 (95% CI: 3.0, 20). The corresponding HR for LN was 4.9 (95% CI: 1.8, 13.7; P = 0.002). Conclusion. The risk of MI and CVM, but not of stroke, is significantly higher in SLE patients with LN than SLE patients without LN.