Meta-analysis «Maxwell L, Singh JA. Abatacept for rheumatoid arth...»1, «»1 of seven trials with 2908 patients were included in this analysis; 1863 were randomized to abatacept and 1045 to placebo. They were RCTs comparing abatacept alone or in combination with DMARDs or biologics to placebo or other DMARDs or biologics. Abatacept was administered intravenously in all trials. Patients were at least 16 years of age meeting the ACR 1987 revised criteria for rheumatoid arthritis. All trials were sponsored by Bristol-Myers Squibb, the manufacturer of abatacept.
The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2007, Issue 1), MEDLINE (from 1966), EMBASE (from 1980), ACP Journal Club (from 2000), and Biosis Previews (from 1990) in March 2007 and December 2008 were searched to select the trails.
The primary outcome is the ACR 50 response rate to treatment with abatacept. Specific adverse event outcomes of interest were: adverse events, including allergic reactions, and infections; serious adverse events, including serious infections, and lymphoma; and withdrawals due to lack of efficacy, and adverse events. Secondary outcomes was ACR 20 and 70 response.
The risk of bias of the included studies was assessed as recommended by the Cochrane Handbook for Systematic Reviews of Interventions. A funnel plot was performed to assess the possibility of publication bias.
A statistically significant higher ACR 70 response was found at six and 12 months in abatacept-treated patients versus control group. The RR at six months was 3.53 (95 % CI 2.41–5.16) and 4.02 (95 % CI 2.62–6.18) at 12 months in favor of abatacept.
Total adverse events were significantly greater in the abatacept group compared to placebo but the relative risk was low (RR 1.05, 95 % CI 1.01–1.08).
Total serious adverse events, withdrawals due to adverse events, serious infections, upper respiratory infections, malignancies, and mortality were not statistically significantly different between the treatment and control groups, based on pooled results at six and 12 months. Risk of serious infections at 12 months was just statistically significant (Peto OR 1.82, 95 % CI 1.00–3.32). Total withdrawals favored the abatacept-treated group (RR 0.60, 95 % CI 0.52–0.70).
The level of evidence is "moderate" for the short-term efficacy outcomes of ACR 50 response, physical function, and disease activity. Longer-term adverse event data was judged to be of "low" level quality as it was based on observational data (extensions of RCTs).