Treatment of pure membranous lupus nephropathy with prednisone and azathioprine: an open-label trial.

Background: The aim of this study was to report the outcome of pure membranous lupus nephropathy treated with prednisone and azathioprine (AZA).

Methods: Consecutive patients with pure membranous lupus glomerulonephritis (World Health Organization [WHO] Va and Vb) from 4 regional hospitals were recruited for an open-label treatment trial consisting of prednisone and AZA. Remission status was evaluated at 12 months. Maintenance treatment with low-dose prednisone and AZA was continued indefinitely for those who achieved remission. Factors predictive of initial renal remission and subsequent relapse were studied by statistical analyses.

Results: Thirty-eight patients (31 women and 7 men) were studied. The mean age was 35.0 +/- 9.2 years, and the duration of systemic lupus erythematosus was 48.5 +/- 59 months. Seventeen (45%) patients had WHO class Va lupus nephritis, whereas 21 (55%) had class Vb disease. Two patients withdrew from the protocol because of idiosyncratic reactions to AZA. At 12 months, 24 (67%) patients achieved complete remission (CR), 8 (22%) achieved partial remission (PR), and 4 (11%) were treatment resistant. Patients who achieved CR or PR were maintained on low-dose prednisone and AZA. Over a mean follow-up period of 90.4 +/- 59 months, 6 (19%) patients had relapse of nephritis (proteinuric flare in 4 and nephritic flare in 2). The cumulative risk of renal relapse was 12% at 36 months and 16% at 60 months. No particular clinical variables were found to predict renal remission or relapses. Over a mean follow-up of 90 months, 13% of patients had decline of creatinine clearance by 20%, but none had doubling of serum creatinine. Renal outcome was not significantly worse in patients presenting with nephrotic syndrome. Treatment generally was well tolerated.

Conclusion: A combination of prednisone and AZA is reasonably effective for the initial treatment of pure membranous lupus nephritis. Severe adverse effects are uncommon. The additional efficacy of AZA in comparison with prednisone alone has to be confirmed with randomized, controlled trials.