Seven RCTs were included (2,741 patients, range 20 to 1,023. Text and Table 1 differed). Only two trials were at low risk of bias: randomisation was unclear in four studies; concealment unclear in one study; two studies were double-blind, four studies were single-blind and one study unblinded.
There was no significant difference in risk of relapse with once-daily dosing versus conventional dosing (RR 0.94, 95% CI 0.82 to 1.08; Ι²=33%; seven studies) with borderline heterogeneity and no evidence of funnel plot asymmetry (Egger's Test, p=0.47). There was no significant difference in effect for studies using clinical criteria to define relapse, including clinical and endoscopic criteria (Ι²=63%; three studies), clinical criteria (Ι²=22%; three studies) or endoscopic criteria (one study).
Analysis by mesalamine formulation used found once daily versus conventional use of one formulation (Pentass) significantly reduced the risk of relapse (RR 0.75, 95% CI 057 to 0.99; one study) but the effect was not significant for the other formulations (Asacol, three studies; MMX, one study; Salofalk, one study). There were no significant differences in effect for studies in terms of non-compliance, adverse events, different daily dosage or risk of bias, where this data were reported.