Ali Rezaie, M Ellen Kuenzig, Eric I Benchimol, Anne Marie Griffiths, Anthony R Otley, A Hillary Steinhart, Gilaad G Kaplan, Cynthia H Seow

Corticosteroids are commonly used for the induction of remission in Crohn's disease. However, traditional corticosteroids can cause significant adverse events. Budesonide is an alternative glucocorticoid with limited systemic bioavailability. The primary objective was to evaluate the efficacy and safety of oral budesonide for the induction of remission in Crohn's disease. The following electronic databases were searched up to June 2014: MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, the Cochrane IBD/FBD Group Specialised Trial Register, and ClinicalTrials.gov. Reference lists of articles, as well as conference proceedings were manually searched. Randomised controlled trials comparing budesonide to a placebo or active comparator were considered for inclusion. Two independent investigators reviewed studies for eligibility, extracted the data and assessed study quality. Methodological quality was assessed using the Cochrane risk of bias tool The overall quality of the evidence supporting the outcomes was evaluated using the GRADE criteria. Meta-analysis was performed using RevMan 5.3.5 software. The primary outcome was induction of remission (defined by a Crohn's disease activity index (CDAI) < 150) by week 8 to 16 of treatment. Secondary outcomes included: time to remission, mean change in CDAI, clinical, histological or endoscopic improvement, improvement in quality of life, adverse events and early withdrawal. We calculated the relative risk (RR) and corresponding 95% confidence intervals (CIs) for each dichotomous outcome and the mean difference and corresponding 95% CI for each continuous outcome. Data were analyzed on an intention-to-treat basis. A random-effects model was used for the pooled analyses. The overall quality of the evidence supporting the primary outcomes and selected secondary outcomes was evaluated using the GRADE criteria. Fourteen studies (1805 patients) were included: Nine (779 patients) compared budesonide to conventional corticosteroids, three (535 patients) were placebo-controlled, and two (491 patients) compared budesonide to mesalamine. Ten studies were judged to be at low risk of bias. Three studies were judged to be at high risk of bias due to open label design. One study was judged to be at high risk of bias due to selective reporting. After eight weeks of treatment, 9 mg budesonide was significantly more effective than placebo for induction of clinical remission. Forty-seven per cent (115/246) of budesonide patients achieved remission at 8 weeks compared to 22% (29/133) of placebo patients (RR 1.93, 95% CI 1.37 to 2.73; 3 studies, 379 patients). A GRADE analysis indicated that the overall quality of the evidence for this outcome was moderate due to sparse data (144 events). Budesonide was significantly less effective than conventional steroids for induction of remission at eight weeks. Fifty-two per cent of budesonide patients achieved remission at week 8 compared to 61% of patients who received conventional steroids (RR 0.85, 95% CI 0.75 to 0.97; 8 studies, 750 patients). A GRADE analysis indicated that the overall quality of the evidence for this outcome was moderate due to risk of bias. Budesonide was significantly less effective than conventional steroids among patients with severe disease (CDAI > 300) (RR 0.52, 95% CI 0.28 to 0.95). Studies comparing budesonide to mesalamine were not pooled due to heterogeneity (I(2) = 81%). One study (n = 182) found budesonide to be superior to mesalamine for induction of remission at 8 weeks. Sixty-eight per cent (63/93) of budesonide patients were in remission at 8 weeks compared to 42% (37/89) of mesalamine patients (RR 1.63, 95% CI 1.23 to 2.16). The other study found no statistically significant difference in remission rates at eight weeks. Sixty-nine per cent (107/154) of budesonide patients were in remission at 8 weeks compared to 62% (132/242) of mesalamine patients (RR 1.12, 95% CI 0.95 to 1.32). Fewer adverse events occurred in those treated with budesonide compared to conventional steroids (RR 0.64, 95% CI 0.54 to 0.76) and budesonide was better than conventional steroids in preserving adrenal function (RR for abnormal ACTH test 0.65, 95% CI 0.55 to 0.78). Budesonide is more effective than placebo for induction of remission in Crohn's disease. Although short-term efficacy with budesonide is less than with conventional steroids, particularly in those with severe disease or more extensive colonic involvement, the likelihood of adverse events and adrenal suppression with budesonide is lower. The current evidence does not allow for a firm conclusion on the relative efficacy of budesonide compared to 5-ASA products.