Seven double-blind RCTs were included in the review (n=2,100 patients). The sample size of included trials ranged from 20 to 721 patients. The length of follow-up ranged from 14 weeks to two years.
American College of Rheumatology (ACR) short-term responses (within 30 weeks): There was a statistically significant improvement in the infliximab group up to 30 weeks in ACR 20% (RR 1.87, 95% CI 1.43 to 2.45; I2=68%; five trials; n=1,287 patients), ACR 50% (RR 2.68, 95% CI 1.79 to 3.99; I2=58%; six trials; n=1,461 patients), and ACR 70% (RR 2.68, 95% CI 1.78 to 4.03; I2=15%; six trials; n=1,461 patients) compared with the placebo group. Statistical heterogeneity, where present, appeared to be caused by one trial.
ACR longer-term responses (one to two years): There was a statistically significant improvement in ACR 50% in the infliximab group up to two years (RR 1.55, 95% CI 1.16 to 2.08; I2=20%; three trials; n=835 patients). There was no statistically significant difference in ACR 20% or ACR 70% in the infliximab group compared with the placebo group up to two years.
Safety: There was no statistically significant difference between infliximab and placebo in terms of infection, serious adverse events, serious infections, malignancy, death or any adverse reaction. However, there was a statistically significant higher number of infusion reactions in the infliximab group compared with the placebo group (RR 1.97, 95% CI 1.12 to 3.45; three trials; n=1,042 patients).
Withdrawals: There were statistically more withdrawals due to adverse events in the infliximab group compared with the placebo group (RR 2.05, 95% CI 1.33 to 3.16; seven trials; n=2,132). However, there were statistically significantly fewer withdrawals due to lack of efficacy in the infliximab group compared with the placebo group (RR 0.41, 95% CI 0.18 to 0.95; three trials, n=1,120 patients).