Table 3 Frequently occurring acute infusional events (>2.0% of patients in any group) to day 197 and day 365 Days 1–197 Abatacept + MTX (n = 156) n (%) 8 (5.1) 0 2 (1.3) 2 (1.3) 1 (0.6) 0 0 0 0 Placebo + MTX (n = 110) Infliximab + MTX (n = 165) n (%) 11 (10.0) 0 2 (1.8) 1 (0.9) 0 0 1 (0.9) 0 0 n (%) 30 (18.2) 7 (4.2) 7 (4.2) 6 (3.6) 4 (2.4) 4 (2.4) 4 (2.4) 2 (1.2) 2 (1.2) Days 1–365 Abatacept + MTX (n = 156) n (%) 11 (7.1) 0 2 (1.3) 3 (1.9) 1 (0.6) 0 0 0 1 (0.6) Infliximab + MTX (n = 165) n (%) 41 (24.8) 8 (4.8) 7 (4.2) 7 (4.2) 5 (3.0) 5 (3.0) 8 (4.8) 5 (3.0) 4 (2.4) n (%) 13 (11.8) 3 (2.7) 0 0 1 (0.9) 1 (0.9) 1 (0.9) 0 0 0 0 0 0 0 0 0 0 0 0 0 n (%) 19 (11.5) 7 (4.2) 2 (1.2) 0 0 0 0 1 (0.6) 1 (0.6) 1 (0.6) 1 (0.6) 1 (0.6) 1 (0.6) 0 0 0 0 0 0 0 n (%) 15 (9.6) 3 (1.9) 2 (1.3) 1 (0.6) 0 0 0 0 0 0 0 0 0 1 (0.6) 0 0 0 0 0 0 n (%) 30 (18.2) 14 (8.5) 3 (1.8) 0 1 (0.6) 0 0 1 (0.6) 1 (0.6) 1 (0.6) 1 (0.6) 1 (0.6) 1 (0.6) 0 1 (0.6) 1 (0.6) 1 (0.6) 1 (0.6) 1 (0.6) 1 (0.6) Extended report Acute infusional events Total patients with AEs Hypotension Headache Nausea Flushing Dyspnea Urticaria Pruritus Dizziness AE, adverse event; MTX, methotrexate. peritoneal TB died during the second 6 months of the trial due to septic shock following surgery. One patient who was randomised to the placebo group died while receiving abatacept between days 198–365 from pneumonia and sepsis. The investigator assessment deemed the death possibly related to study treatment. Acute infusional events (7.1 vs 24.8%; table 3) were lower with abatacept vs infliximab, respectively. Up to day 365, infections and infestations were reported in 59.6 and 68.5% of the abatacept and infliximab groups, respectively. Serious infections were reported in 1.9% of abatacept-treated patients and 8.5% of infliximab-treated patients (table 4). A total of five serious opportunistic infections were reported, all occurring in the infliximab group in one patient for each (encephalitis herpetic, lung infection pseudo- monal, peritoneal TB, P jiroveci pneumonia and pulmonary TB). Both cases of TB were in patients who were PPD test negative and chest x ray negative at study entry. Between days 1–365, autoimmune symptoms or disorders were uncommon (,1%) Table 4 Serious infectious events to day 197 and day 365 Total patients with SAEs Infections and infestations Pneumonia Sinusitis Postoperative wound infection Soft tissue abscess Infective bursitis Bronchitis Cellulitis Gastroenteritis Herpes zoster Lung infection pseudomonal Pneumocystis jiroveci pneumonia Infection skin ulcer Encephalitis herpetic Erysipelas Lobar pneumonia Peritoneal tuberculosis Pulmonary tuberculosis Septic shock 1102 MTX, methotrexate; SAE, serious adverse event. n (%) 8 (5.1) 2 (1.3) 2 (1.3) 1 (0.6) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Ann Rheum Dis 2008;67:1096–1103. doi:10.1136/ard.2007.080002 and occurred at a similar frequency in the abatacept and infliximab groups (table 2). No additional malignant neoplasms were reported in either group between days 198–365. DISCUSSION The multi-centre, double-blind, placebo-controlled ATTEST trial, examining the relative efficacy and safety of abatacept or infliximab vs placebo, confirms that both biologics are effective for the treatment of RA. Over the 12-month study, a relative difference in safety was observed, with fewer SAEs, serious infections, acute infusional events and discontinuations due to AEs in the abatacept group than the infliximab group. Following 6 months of treatment, abatacept and infliximab on a background of MTX significantly reduced the signs and symptoms of disease (DAS28 (ESR); ACR 20, 50 and 70), and improved physical function (HAQ-DI) and quality of life (SF- 36) compared with placebo, in patients with an inadequate response to MTX. The relative efficacy of abatacept and infliximab at day 197 was similar, as the 95% CIs for the Days 1–197 Abatacept + MTX (n = 156) Placebo + MTX (n = 110) Inflixima + MTX (n = 165) Days 1–365 Abatacept + MTX (n = 156) Infliximab + MTX (n = 165)