Survival analysis of mortality and development of lupus nephritis in patients with systemic lupus erythematosus up to 40 years of follow-up

OBJECTIVES: Patients with SLE have increased mortality compared with age- and sex-matched controls. LN is a severe manifestation of SLE and an important cause of death. We carried out a retrospective survival analysis to investigate factors that could influence the risk of mortality and LN in a large multi-ethnic cohort of patients with SLE. METHODS: By careful review of medical records, we identified 496 patients with SLE for whom we had complete information regarding the period of observation and occurrence of death and nephritis. Patients were stratified into groups according to sex, ethnicity, age at start of follow-up and time period of diagnosis. Kaplan–Meier analysis was used to investigate differences between the groups. RESULTS: Of the 496 patients in the study, 91 (18.3%) died, 165 (33.3%) developed LN and 33 (6.7%) developed end-stage renal failure. There was no difference between men and women in either mortality or development of LN. Caucasian patients were significantly less likely to develop LN than other ethnic groups (P < 0.0001) but not less likely to die. Patients diagnosed before the median age of 28 years were significantly more likely to develop LN (P < 0.0001) but significantly less likely to die (P = 0.0039) during the period of observation. There has been a significant improvement in survival in patients diagnosed between 1978 and 1989 and those diagnosed between 2006 and 2011 (P = 0.019). CONCLUSION: In our cohort, non-Caucasian ethnicity and younger age at diagnosis are associated with the risk of developing LN. There is evidence of improvement in survival of patients with SLE over time.