Twelve RCTs (n = 4,899) were included in the review; 3,919 patients received infliximab plus methotrexate and 980 methotrexate alone. Nine RCTs used double-blinding, seven reported adequate allocation concealment and six used an intention-to-treat analysis.
Infliximab at 3 mg/kg plus methotrexate was significantly more effective than methotrexate alone on all American College of Rheumatology (ACR) efficacy measures (ACR 20 odds ratio 3.52, 95% CI: 2.14, 5.79; ACR 50 odds ratio 2.87, 95% CI: 2.28, 3.61; ACR70 odds ratio 2.42, 95% CI: 1.87, 3.13).
Infliximab at 10mg/kg plus methotrexate was also significantly more effective than methotrexate alone on all American College of Rheumatology (ACR) efficacy measures (ACR20 odds ratio 5.06, 95% CI: 3.88, 6.59; ACR50 odds ratio 5.72, 95% CI: 4.05, 8.08; ACR 70 odds ratio 7.32, 95% CI: 2.28, 23.50).
Regimes using higher doses of infliximab were significantly more effective on the outcome of ACR50 than lower doses (p=0.001).
Subgroup results were also reported separately for treatments administered at 4 and 8 week intervals. There was some evidence of increased efficacy with 4 weekly compared to 8 weekly administration for 3 mg/kg infliximab (ACR20 p=0.03; ACR50 p>0.05; ACR70 p=0.02) but no such effect for 10 mg/kg treatments (p>0.05 in all cases).
Incidence of adverse effects was not significantly different between the groups either for infliximab 3 mg/kg plus methotrexate versus methotrexate alone every eight weeks or for infliximab 10 mg/kg plus methotrexate versus methotrexate alone every eight weeks. There was no statistically significant difference between groups treated with lower or higher doses of infliximab given every four versus every eight weeks.
Further results of subgroup analyses were extensively reported, including findings of increased efficacy for high doses in patients with severe disease activity, in patients with concomitant steroid use and in trials lasting longer than 54 weeks.