Background: The present study was designed to know the clinical course of lupus nephritis and the risk factors associated with the development of end stage renal disease.
Methods: This a retrospective study performed in a cohort of 154 patients with biopsy proven lupus nephritis that were seen in our hospital between 1984 and 1990. The clinical records of all patients were reviewed in order to collect the following information at the time of the biopsy: age, sex, number and type of lupus criteria according with the American College of Reumathology, mean arterial pressure, serum creatinine, BUN, and albumin, as well as urinary protein excretion. The follow up was registered from the day the biopsy was performed to one of the following end points: end stage renal disease (defined as requirement of chronic dialysis), death or the end of study. All biopsies were analyzed by light microscopy to obtain the hystological subtype of lupus nephritis (WHO classification) and when type IV was diagnosed, the activity and chronicity indexes were also assessed. Kaplan-Meier survival tables were constructed. The association of clinical and laboratory variables with the development of end stage renal disease was obtained by log rank analysis. Variables obtained as significant were used to evaluate their individual impact using either the Cox multivariate proportional hazard method.
Results: Follow up was complete in 144 patients with a follow up time of 68 +/- 38 months. Ninety three patients were female with mean age of 28 +/- 9 years. At the time of the biopsy, renal manifestations had been present for 35 +/- 38 months and the number of lupus criteria per patient were 4 +/- 1. The clinical picture at the time of the biopsy was: nephrotic syndrome in 60%, non nephrotic proteinuria in 40%, and nephritic syndrome in only 2%. The hystological type of lupus nephritis was: I in 2%, II in 8%, III in 6%, IV in 71% and V in 11%. At the end of the study 28 patients developed end stage renal disease. For the whole group the survival of renal function was 85% at 70 months and 70% at 140 months. All, but one patient that developed end stage renal disease exhibited type IV nephropathy. In this subpopulation the mean activity and chronicity indexes were 8.5 +/- 3.5 and 3.1 +/- 2.4, respectively. By multivariate analysis the strongest predictors of end stage renal disease were the serum creatinine at the time of the biopsy, chronicity index, and age. The higher the serum creatinine and chronicity index at the time of biopsy, the higher the probability of developing end stage renal disease.
Conclusions: We conclude that the clinical course of lupus nephritis in our population is similar to that seen in other series. The variables indicating advanced renal disease, such as high serum creatinine and chronicity index, were the strongest predictors of end stage renal disease.