Oral 5-aminosalicylic acid for maintenance of remission in ulcerative colitis

Abstract

To assess the efficacy, dose-responsiveness and safety of the newer release formulations of 5-aminosalicylic acid (5-ASA) compared to placebo or sulfasalazine (SASP) in the maintenance of remission in ulcerative colitis. A computer-assisted literature search for relevant studies (1981-1998) was performed using MEDLINE, BIOS, the Cochrane Controlled Trials Register, the Inflammatory Bowel Disease Trials Register, and Science Citation Index, followed by a manual search of reference lists from previously retrieved articles, review articles, symposia proceedings, and abstracts from major gastrointestinal conferences. Studies were accepted for analysis if they were prospective, randomized, double-blinded, and placebo- or SASP-controlled clinical trials of parallel design with treatment duration of at least six months. Based on an intention to treat principle, the primary outcome was the failure to maintain clinical or endoscopic remission. Secondary outcomes were the number of patients experiencing adverse events, the number of patients withdrawn due to adverse events, and exclusions or withdrawals after entry into the study (not due to relapse). All data were analyzed using the Peto odds ratio and corresponding 95% confidence intervals (CI). The Peto odds ratio for the failure to maintain clinical or endoscopic remission (withdrawals and relapses) for 5-ASA versus placebo was 0. 47 (95% CI, 0.36 to 0.62) with an NNT of 6. These values were also calculated for the trials in which SASP and 5-ASA were compared, revealing an odds ratio of 1.29 (95% CI, 1.05 to 1.57), with a negative NNT value (-19), suggesting a higher degree of therapeutic effectiveness for SASP. SASP and 5-ASA had similar adverse event profiles, with odds ratios of 1.16(0.62 to 2.16), and 1.31(0.86 to 1.99), respectively. The NNH values were determined to be 171 and 78 respectively. The newer 5-ASA preparations were superior to placebo in maintenance therapy. However, the newer preparations had a statistically significant therapeutic inferiority relative to SASP.