Effect of Renal Disease on the Standardized Mortality Ratio and Life Expectancy of Patients With Systemic Lupus Erythematosus

Abstract

OBJECTIVE: To study the effect of renal disease on the standardized mortality ratio (SMR) and life expectancy of patients with systemic lupus erythematosus (SLE). METHODS: Patients whose diagnosis met ≥4 American College of Rheumatology criteria for SLE were longitudinally followed up from 1995 to 2011. The cumulative survival rate, SMR, and life expectancy were calculated, and the effect of renal involvement, histologic class of lupus nephritis, renal damage, and end-stage renal disease (ESRD) on these parameters was evaluated. RESULTS: Of the 694 SLE patients studied, 368 (53%) had renal disease, and the distribution of histologic classes (among 285 patients) was class I (1%), class II (6%), class III (19%), class IV (47%), class III/IV + class V (10%), and class V (16%). Renal damage was present in 79 patients (11%), and 24 (3%) developed ESRD. The age- and sex-adjusted hazard ratios (HRs) of mortality in SLE patients with renal disease, those with renal damage, and those with ESRD, as compared to those without, were 2.23 (95% confidence interval [95% CI] 1.29-3.85), 3.59 (95% CI 2.20-5.87), and 9.20 (95% CI 4.92-17.2), respectively. Proliferative lupus nephritis (adjusted HR 2.28, 95% CI 1.22-4.24), but not the pure membranous type (adjusted HR 1.09, 95% CI 0.38-3.14), was associated with a significant increase in mortality. The age- and sex-adjusted SMRs of SLE patients without renal involvement, those with lupus nephritis, those with proliferative nephritis, those with pure membranous nephritis, those with renal damage, and those with ESRD were 4.8 (95% CI 2.8-7.5), 9.0 (95% CI 6.7-11.9), 9.8 (95% CI 6.5-14.1), 6.1 (95% CI 2.0-14.1), 14.0 (95% CI 9.1-20.5), and 63.1 (95% CI 33.6-108.0), respectively. The life expectancy of SLE patients with renal disease and those with renal damage was reduced by 15.1 years and 23.7 years, respectively, compared to the general population. CONCLUSION: The presence of renal disease, in particular proliferative nephritis causing renal insufficiency, significantly reduces the survival and life expectancy of SLE patients.