Forty-nine studies (90 treatment arms) were included in the review. Out of 6,490 patients, 3,977 received oral preparations and 2,513 received rectal formulations. The reported study details did not make it clear how many trials were placebo-controlled or used blinded outcome assessors.
Based on the definitions in the primary studies, 43.7% of patients with ulcerative colitis who were treated with 5-ASA achieved mucosal healing. Within the subgroups, 36.9% receiving oral treatment and 50.3% receiving rectal treatment achieved mucosal healing.
There was a significantly higher rate of mucosal healing success in patients treated with oral 5-ASA preparations at a dosage of at least 3g compared with less than 3g (RR 1.19, 95% CI 1.07 to 1.32; Ι²=0%; nine trials). No such differences were noted in the two available rectal studies.
It was not possible to directly compare treatment duration in terms of efficacy in achieving mucosal healing with the available data. There appeared to be little difference between short (<6 weeks) versus long (>6 weeks) treatment periods in the rectal group and a slight tendency for high rates of mucosal healing in longer term oral treatment groups.
Direct comparisons of granulate versus tablet oral treatment found no significant differences (2 trials). There were no significant differences in mucosal healing rates when comparing 5-ASA foam versus enema rectal preparations (5 trials).