CAN WE PREVENT THE INEVITABLE? THE USE OF 6-MERCAPTOPURINE OR MESALAMINE TO PREVENT POSTOPERATIVE RECURRENCE IN PATIENTS WITH CROHN DISEASE:

Interventions for maintenance of surgically induced remission in Crohn's disease: a network meta-analysis

BACKGROUND

Crohn's disease (CD) is a chronic disease of the gut. About 75% of people with CD undergo surgery at least once in their lifetime to induce remission. However, as there is no known cure for the disease, patients usually experience a recurrence even after surgery. Different interventions are routinely used in maintaining postsurgical remission. There is currently no consensus on which treatment is the most effective.

OBJECTIVES

To assess the effects and harms of interventions for the maintenance of surgically induced remission in Crohn's disease and rank the treatments in order of effectiveness.

SEARCH METHODS

We searched the Cochrane IBD Group Specialized Register, CENTRAL, MEDLINE, and Embase from inception to 15 January 2019. We also searched reference lists of relevant articles, abstracts from major gastroenterology meetings, ClinicalTrials.gov, and the WHO ICTRP. There was no restriction on language, date, or publication status.

SELECTION CRITERIA

We considered for inclusion randomised controlled trials (RCTs) that compared different interventions used for maintaining surgically induced remission in people with CD who were in postsurgical remission. Participants had to have received maintenance treatment for at least three months. We excluded studies assessing enteral diet, diet manipulation, herbal medicine, and nutritional supplementation.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected relevant studies, extracted data, and assessed the risk of bias. Any disagreements were resolved by discussion or by arbitration of a third review author when necessary. We conducted a network meta-analysis (NMA) using a Bayesian approach through Markov Chain Monte Carlo (MCMC) simulation. For the pairwise comparisons carried out in Review Manager 5, we calculated risk ratios (RR) with their corresponding 95% confidence intervals (95% CI). For the NMA, we presented hazard ratios (HR) with corresponding 95% credible intervals (95% CrI) and reported ranking probabilities for each intervention. For the NMA, we focused on three main outcomes: clinical relapse, endoscopic relapse, and withdrawals due to adverse events. Data were insufficient to assess time to relapse and histologic relapse. Adverse events and serious adverse events were not sufficiently or objectively reported to permit an NMA. We used CINeMA (Confidence in Network Meta-Analysis) methods to evaluate our confidence in the findings within networks, and GRADE for entire networks.

MAIN RESULTS

We included 35 RCTs (3249 participants) in the review. The average age of study participants ranged between 33.6 and 38.8 years. Risk of bias was high in 18 studies, low in four studies, and unclear in 13 studies. Of the 35 included RCTs, 26 studies (2581 participants; 9 interventions) were considered eligible for inclusion in the NMA. The interventions studied included 5-aminosalicylic acid (5-ASA), adalimumab, antibiotics, budesonide, infliximab, probiotics, purine analogues, sulfasalazine, and a combination of sulfasalazine and prednisolone. This resulted in 30 direct contrasts, which informed 102 mixed-treatment contrasts.The evidence for the clinical relapse network (21 studies; 2245 participants) and endoscopic relapse (12 studies; 1128 participants) were of low certainty while the evidence for withdrawal due to adverse events (15 studies; 1498 participants) was of very low certainty. This assessment was due to high risk of bias in most of the studies, inconsistency, and imprecision across networks. We mainly judged individual contrasts as of low or very low certainty, except 5-ASA versus placebo, the evidence for which was judged as of moderate certainty.We ranked the treatments based on effectiveness and the certainty of the evidence. For clinical relapse, the five most highly ranked treatments were adalimumab, infliximab, budesonide, 5-ASA, and purine analogues. We found some evidence that adalimumab (HR 0.11, 95% Crl 0.02 to 0.33; low-certainty evidence) and 5-ASA may reduce the probability of clinical relapse compared to placebo (HR 0.69, 95% Crl 0.53 to 0.87; moderate-certainty evidence). However, budesonide may not be effective in preventing clinical relapse (HR 0.66, 95% CrI 0.27 to 1.34; low-certainty evidence). We are less confident about the effectiveness of infliximab (HR 0.36, 95% CrI 0.02 to 1.74; very low-certainty evidence) and purine analogues (HR 0.75, 95% CrI 0.55 to 1.00; low-certainty evidence). It was unclear whether the other interventions reduced the probability of a clinical relapse, as the certainty of the evidence was very low.Due to high risk of bias and limited data across the network, we are uncertain about the effectiveness of interventions for preventing endoscopic relapse. Whilst there might be some evidence of prevention of endoscopic relapse with adalimumab (HR 0.10, 95% CrI 0.01 to 0.32; low-certainty evidence), no other intervention studied appeared to be effective.Due to high risk of bias and limited data across the network, we are uncertain about the effectiveness of interventions for preventing withdrawal due to adverse events. Withdrawal due to adverse events appeared to be least likely with sulfasalazine (HR 1.96, 95% Crl 0.00 to 8.90; very low-certainty evidence) and most likely with antibiotics (HR 53.92, 95% Crl 0.43 to 259.80; very low-certainty evidence). When considering the network as a whole, two adverse events leading to study withdrawal (i.e. pancreatitis and leukopenia) occurred in more than 1% of participants treated with an intervention. Pancreatitis occurred in 2.8% (11/399) of purine analogue participants compared to 0.17% (2/1210) of all other groups studied. Leukopenia occurred in 2.5% (10/399) of purine analogue participants compared to 0.08% (1/1210) of all other groups studied.

AUTHORS' CONCLUSIONS

Due to low-certainty evidence in the networks, we are unable to draw conclusions on which treatment is most effective for preventing clinical relapse and endoscopic relapse. Evidence on the safety of the interventions was inconclusive, however cases of pancreatitis and leukopenia from purine analogues were evident in the studies. Larger trials are needed to further understand the effect of the interventions on endoscopic relapse.

Oral 5-aminosalicylic acid for maintenance of surgically-induced remission in Crohn's disease

BACKGROUND

The use of 5-aminosalicylates (5-ASAs) in Crohn's disease (CD) is controversial.  A recent Cochrane review found that 5-ASAs are not effective for the maintenance of medically-induced remission in CD, but their role in the maintenance of surgically-induced remission is unclear.

OBJECTIVES

The objectives were to evaluate the efficacy and safety of 5-ASA agents for the maintenance of surgically-induced remission in CD.

SEARCH STRATEGY

The search was standardised and not limited by language and included electronic searching (MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Cochrane Inflammatory Bowel Disease Group Specialized Trials Register), reference searching of all included studies, abstracts from major meetings, personal contacts and drug companies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) which compared 5-ASAs with either placebo or another intervention, with treatment durations of at least 6 months were considered for inclusion. Participants were patients of any age with CD in remission following surgery. Primary outcome measures were clinical relapse or endoscopic recurrence as defined by the primary studies. Secondary endpoints were the occurrence of adverse events.

DATA COLLECTION AND ANALYSIS

Relevant papers were identified and the authors independently assessed the eligibility of trials. Methodological quality was assessed using the Cochrane risk of bias tool.The Cochrane RevMan software was used for analyses. Patients with final missing outcomes were assumed to have relapsed. Odds ratio (OR) and 95% confidence intervals (95% CI) were calculated based on the fixed effects model. The chi square and I(2) statistics were used to assess statistical heterogeneity.

MAIN RESULTS

Nine RCTs were included in the review. Seven studies compared oral 5-ASA with placebo and two compared oral 5-ASA with purine antimetabolites (azathioprine or 6-mercaptopurine). 5-ASA was significantly more effective than placebo for preventing relapse (OR 0.68, 95% CI, 0.52 to 0.90). There was no statistically significant heterogeneity among the 8 trials comparing 5-ASA with placebo (P=0.47). No statistically significant difference in adverse events was found for 5-ASA versus placebo (OR 1.02, 95%CI, 0.60 to 1.76). No statistically significant difference was found between 5-ASA and purine antimetabolites for preventing relapses (OR 1.08 95% CI, 0.63 to 1.85).

AUTHORS' CONCLUSIONS

The pooled analyses suggest that 5-ASA preparations may be superior to placebo for the maintenance of surgically-induced remission in patients with CD. The results of the pooled analyses should be interpreted with caution because adequately powered studies demonstrated no difference and publication bias (failure to publish negative studies) may be an issue. The potential benefit provided by 5-ASA drugs is modest with a number needed to treat of approximately 16 to 19 patients to avoid one relapse which raises issues about the cost-effectiveness of this therapy. However, 5-ASA drugs are safe and well tolerated. The incidence of adverse events was not different in patients receiving 5-ASA compared with those receiving placebo. There is insufficient evidence to allow any conclusions on how 5-ASA preparations compare with azathioprine or 6-mercaptopurine.