Anti-infliximab and anti-adalimumab antibodies in relation to response to adalimumab in infliximab switchers and anti-tumour necrosis factor naive patients: a cohort study

OBJECTIVE: To investigate how antibodies against anti-tumour necrosis factor (anti-TNF) agents influence response after switching from infliximab to adalimumab in rheumatoid arthritis (RA). METHODS: This cohort study consisted of 235 patients with RA, all treated with adalimumab. At baseline 52 patients (22%) had been previously treated with infliximab ('switchers'), and 183 (78%) were anti-TNF naive. Disease activity (using the 28-joint count Disease Activity Score (DAS28)) and presence of antibodies against infliximab and adalimumab were assessed. Clinical response to adalimumab was compared between switchers and anti-TNF naive patients and their anti-infliximab and anti-adalimumab antibody status. RESULTS: After 28 weeks of adalimumab treatment the decrease in DAS28 (Delta DAS28) for the 235 patients was 1.6+/-1.5 (mean+/-SD). Anti-adalimumab antibodies were detected in 46 patients (20%). Delta DAS28 was 1.8+/-1.4 in patients without anti-adalimumab and 0.6+/-1.3 in patients with anti-adalimumab (p