Cyclosporine nephrotoxicity in type 1 diabetic patients: A 7-year follow-up study

OBJECTIVE - To evaluate kidney function 7 years after the end of treatment with cyclosporine A (CsA) (initial dosage of 9.3 tapered off to 7.0 mg · kg^-1 · day^-1) in young patients (mean age 20 years) with newly diagnosed type 1 diabetes participating in a randomized, double-blind, placebo-controlled CsA trial. RESEARCH DESIGN AND METHODS - In this study, 21 patients received CsA for 12.5 ± 4.0 months (mean ± SD) and 19 patients received placebo for 14.4 ± 3.8 months. The two groups were similar with regard to mean arterial blood pressure (BP), urinary albumin excretion rate (UAER), serum creatinine, and estimated glomerular filtration rate (GFR [Cockcroft and Gault]) at initiation of CsA treatment (baseline). HbA(1c) (mean ± SEM) during 7 years of follow-up was also the same: 8.7 ± 0.4 vs. 8.3 ± 0.4% in the CsA and placebo groups, respectively. RESULTS - During the 7 years after cessation of study medication, two CsA group patients and one control patient were lost to follow-up. One placebo-treated patient developed IgA nephropathy (biopsy proven) and was excluded. Four CsA-treated patients developed persistently elevated UAER >30 mg/24 h (n = 3 with microalbuminuria), whereas all the 17 placebo-treated patients had normal UAER (<30 mg/24 h) after 7 years of follow-up. At the end of follow-up, the CsA group had a more pronounced rise in UAER: 2.5-fold (95% CI 1.4-4.5) higher than baseline values vs. 1.1-fold (0.7-1.7) in the placebo-treated group (P < 0.05). Estimated GFR (ml · min^-1 · 1.73 m^-2) declined from baseline to end of follow-up (1994) by 6.3 ± 6.0 in the former CsA group, whereas it rose by 7.4 ± 5.0 in the placebo group (P = 0.05). In 1994, 24-h blood pressure was nearly the same: 131/77 ± 4/2 vs. 127/75 ± 2/2 mmHg (NS) in the CsA and placebo groups, respectively five randomly selected CsA- treated patients had a kidney biopsy performed shortly after the CsA treatment was stopped. Interstitial fibrosis/tubular atrophy and/or arteriolopathy were present in two subjects who both subsequently developed persistent microalbuminuria. CONCLUSIONS - The results of our 7-year follow- up study suggested that short-lasting CsA treatment in young, newly diagnosed type 1 diabetic patients accelerated the rate of progression in UAER and tended to induce a loss in kidney function. Longer term follow-up is mandatory to clarify whether CsA-treated patients are at increased risk of developing clinical nephropathy.