An observational study of outcome in SLE patients with biopsy-verified glomerulonephritis between 1986 and 2004 in a defined area of Southern Sweden: the clinical utility of the ACR renal response criteria and predictors for renal outcome.

Objectives: To test the utility of the World Health Organization (WHO) and International Society of Nephrology/Renal Pathology Society (ISN/RPS) criteria for lupus nephritis (LN) in systemic lupus erythematosus (SLE) and the American College of Rheumatology renal response criteria (ACR-RRC) for renal follow-up in an observational cohort. Method: All 52 biopsy-verified cases of LN during 19 years were identified, and glomerular filtration rate (GFR), serum creatinine, proteinuria, haematuria, Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K), and complement were retrieved at diagnosis of nephritis, after 6 and 12 months, and at the latest visit. Forty-five renal biopsies were available for re-evaluation with the ISN/RPS criteria. Outcome was defined by the ACR-RRC and the final GFR. Results: The mean follow-up time was 9 years; complete renal response (CRR) was achieved in 11 cases, end-stage renal disease (ESRD) in four, and nephrotic syndrome (NS) in one. The final GFR decreased with increasing age at biopsy (p < 0.01) and with interstitial manifestations added to the ISN/RPS classification (p < 0.05). The final GFR correlated with the decrease of proteinuria or casts and actual serum creatinine after 6 months of treatment (all p < 0.05). The outcome defined by ACR-RRC correlated with the nephrological components of SLEDAI-2K after 6 months of therapy (p < 0.01) and with the presence of antibodies to C1q at biopsy (p < 0.05). Conclusions: Renal outcome is correlated with the response to treatment after 6 months and with the addition of interstitial changes to the ISN/RPS classification, which might add useful information for prediction. The ACR-RRC offers a defined alternative to categorize renal response.