5-aminosalicylates and effects on renal function in patients with Crohn's disease

Background: Case reports concerning irreversible renal failure caused by 5-ammosalicylates (5-ASA) have been published. The aim of this study was to investigate the effect of long-term use of 5-ASA on renal function in patients with Crohn's disease (CD). Methods: This was a retrospective survey in 200 consecutive outpatients with CID. Endogenous creatinine clearance (ECC) was estimated from serum creatinine with the Cockroft and Gault formula. The first ECC was chosen close to the start of 5-ASA and the second was the most recent ECC available. Results: In 153 patients (59 men and 94 women), sufficient data were available for analysis. The interval between ECCs was 11 years, with a mean exposure to 5-ASA of 8.6 years. The cumulative dose of 5-ASA amounted to 9 kg. The ECC declined 0.3 +/- 5 mL/min/yr (from 100 +/- 25 to 92 +/- 28 mL/min; P < 0.01). In a multiple linear regression model, duration of the interval was a significant predictor for change in ECC (P < 0.0001), but cumulative dose of 5-ASA was not predictive (P = 0.30). No interstitial nephritis was reported, and in the 8 patients with the largest decline in ECC, comorbidity causing renal function impairment was present. Conclusions: The mean decline in ECC of 0.3 mL/min/yr in patients with CID does not exceed the decline expected from physiologic aging. Furthermore, the cumulative dose of 5-ASA was not a predictor for change in renal function. However, as interstitial nephritis caused by 5-ASA may rarely occur, we still advocate measurements of serum creatinine before and during treatment.