Summary of safety at year 1
| Abatacept + methotrexate (n = 256) | Placebo + methotrexate (n = 253) | |
| n (%) | n (%) | |
| Adverse events | 217 (84.8) | 211 (83.4) |
| Discontinuations due to adverse events | 8 (3.1) | 11 (4.3) |
| Serious adverse events | 20 (7.8) | 20 (7.9) |
| Discontinuations due to serious adverse events | 3 (1.2) | 3 (1.2) |
| Infections | 132 (51.6) | 139 (54.9) |
| Serious infections | 5 (2.0) | 5 (2.0) |
| Autoimmune events | 6 (2.3) | 5 (2.0) |
| Acute infusional events | 16 (6.3) | 5 (2.0) |
| Malignancies | 1 (0.4) | 0 (0.0) |
| Deaths | 2 (0.8) | 4 (1.6) |