Objective: To investigate in common clinical practice the toxicity/efficacy ratio of low dose cyclosporine A (CsA) in patients with advanced rheumatoid arthritis (RA) after 12 months CsA administration.
Methods: One hundred and two patients with RA were included in the study. The initial dose of CsA was 2.5 mg/kg/day, the mean maximum dose was 3.2 mg/kg/day and the dose at 12 months was 2.8 mg/kg/day.
Results: Sixty-nine (68%) patients completed 12 months of treatment. Seventeen (17%) patients discontinued for lack of efficacy and 16 (16%) for toxicity (of which 50% for gastrointestinal intolerance). The clinical efficacy variables improved significantly by 36-42% between entry and Month 6 and remained stable thereafter. The C-reactive protein decreased from 43 U/ml at entry to 22 U/ml (p < 0.0001) at 12 months. Forty-four percent of the patients and 47% of the physicians judged the efficacy as good or very good. The median number of adverse events/patient was 3 but most adverse events were either not clinically important or disappeared after dose reduction. Gastrointestinal (GI) intolerance and nephrotoxicity (> 30% increase in serum creatinine) each occurred in 50% of the patients. GI intolerance was transient in 80% of the patients but accounted for 50% of the premature discontinuations for toxicity. Nephrotoxicity persisted in the 50% of the patients in whom it occurred, despite dose reduction. The mean serum creatinine rose from 70 (13) mumol/l at entry to 86 (23) mumol/l at 12 months (23% increase; p < 0.0001), and this increase had been entirely reached after 3 months. Variables that could significantly predict the occurrence of nephrotoxicity could not be identified.
Conclusion: CsA can be safely and effectively administered to patients with RA for a duration of at least 12 months. An acceptable renal function at entry, close monitoring of the serum creatinine concentration and dose reductions when appropriate are prerequisities.