Abstract: Nine studies met all inclusion criteria. Four different anti-TNF-α agents were evaluated (infliximab in 3 studies, CDP571 in 3 studies, adalimumab in 2 studies, and certolizumab in 1 study). There is evidence from three randomized controlled trials that infliximab maintains clinical remission (RR 2.50; 95% CI 1.64 to 3.80), maintains clinical response (RR 1.66; 95% CI 1.00 to 2.76), has corticosteroid-sparing effects (RR 3.13; 95% CI 1.25 to 7.81), and maintains fistula healing (RR 1.87; 95% CI 1.15 to 3.04) in patients with Crohn's disease with a response to infliximab induction therapy. There were no significant differences in remission rates between infliximab doses of 5 mg/kg or 10 mg/kg. There is evidence that adalimumab maintains clinical remission, clinical response, and has corticosteroid-sparing effects in patients with Crohn's disease who have responded or entered remission with adalimumab induction therapy. There were no significant differences in remission rates between adalimumab 40 mg weekly or every other week. There is evidence from one randomized controlled trial that certolizumab pegol maintains clinical remission (RR 1.68; 95% CI 1.30 to 2.16) and maintains clinical response (RR 1.74; 95% CI 1.41 to 2.13) in patients who have responded to certolizumab induction therapy. There is no evidence to support the use of CDP571 for the maintenance of remission in Crohn's disease. Infliximab 5 mg/kg or 10 mg/kg, given every 8 weeks, is effective for the maintenance of remission and maintenance of fistula healing in patients who have responded to infliximab induction therapy. Adalimumab 40 mg weekly or every other week is effective for the maintenance of remission in patients who have responded to adalimumab induction therapy. Certolizumab pegol 400 mg every 4 weeks is effective for the maintenance of remission in patients who have responded to certolizumab induction therapy. No comparative trials have evaluated the relative efficacy of these agents. Adverse events are similar in the infliximab, adalimumab, and certolizumab groups compared with placebo, but study size and duration generally are insufficient to allow an adequate assessment of serious adverse events associated with long-term use.

Plain-language summary: Nine studies were reviewed. The studies compared TNF-alpha blocking agents with placebo (inactive intravenous infusions or injections) and found that infliximab, adalimumab, and certolizumab pegol were effective in maintaining remission in patients with Crohn's disease who respond to induction therapy with these agents. There is no evidence that CDP571 is an effective maintenance therapy. The TNF-alpha blocking agents appear to be safe for patients with Crohn's disease with equal numbers of patients receiving TNF-alpha blocking agents or placebo reporting side effects such as headache, abdominal pain, nausea, and pain at injection site. There were some serious side effects reported with the use of these agents including infections such as tuberculosis. However, patients can be screened for inactive tuberculosis prior to treatment with TNF-alpha. A link between long term treatment with TNF-alpha blocking agents and cancer is possible but not proven. Data obtained from observational studies including the Crohn's Therapy, Resource, Evaluation and Assessment Tool (TREAT) registry show no increased risk of cancer with the use of TNF-alpha blocking agents in patients with inflammatory bowel disease. The current evidence suggests that the TNF-alpha blocking agents infliximab, adalimumab, and certolizumab pegol are effective maintenance therapy in Crohn's disease. However, the use of these medications needs to be weighed against the potential risk of serious side effects, particularly infection.