Background Abatacept is a novel biological T-cell modulation drug used in RA. Data on patient characteristics, diagnosis, preceding treatment and outcomes of abatacept had been collected since approval in the national Swedish Rheumatology Quality register (SRQ).
Objectives To evaluate the effects of abatacept in clinical practice five years after approval in a cohort of rheumatoid arthritis patients.
Methods Observational data from the SRQ was collected for the period from April 1st, 2006 to September 30th, 2011.Survival analysis (Kaplan Meier curves) with right censoring and log-rank test of equality across strata was performed. Comparisons between all pairs of curves with Tukey-Kramer multiple-comparison adjustments were applied.
Results There were 789 patients who started abatacept treatment between April 2006 and September 2011. 614 patients (487 females, 79.3%) had RA diagnosis with median (min-max) “age at start of abatacept” of 60 years (23-89) and median “disease duration” of 11 years (0.1-67). Median “time since first given biological treatment to abatacept start” was 3.4 years (0-11). Median “abatacept treatment time” was 0.9 years (0-5).
Abatacept was used as a first biological treatment in 68 patients (11%), after one or two previous and unique biological drugs in 341 (56%) patients, after three or more unique biological drugs in 205 (33%) patients. After 1, 2, 3 and 4 years drug survival was 80%, 73%, 63% and 63% respectively in bio-naïve patients, 64%, 51%, 49% and 46% in patients with 1-2 previous biological treatments and 57%, 41%, 30% and 30% in patients with three or more previous biological treatments. Bio-naïve patients had significantly longer drug survival time than patients with three or more previous treatments (p=0.006), and patients with 1-2 previous biological treatments had longer drug survival time than patients with three or more previous treatments.
Disease activity outcomes were measured as DAS28 before treatment and after 3, 6 and 12 months of treatment. A per-protocol analysis was used. There was significant reduction of DAS28 at all time points compared with baseline. Median DAS28 at baseline was 5.5, at 3 months 4.5, at 6 months 4.3 and at 12 months 3.9. The effect of abatacept expressed by DAS28 was significantly better in men than in women at all time points except for 6 months. A longer drug survival was found also in men compared to women (p=0.05). At 1, 2, 3 and 4 years respectively drug survival was 68%, 59%, 54% and 51% in men and 62%, 47%, 40% and 39% in women.
Conclusions In the cohort of 614 RApatients starting abatacept treatment during 2006 – 2011, drug survival time was longer for bio-naïve patients compared to patients treated with previous biological drugs. A gender difference in favour of men was seen in the reduction of disease activity as well as in abatacept drug survival.
Disclosure of Interest S. Lindblad Grant/Research support from: BristolMyersSquibb as an unrestricted research grant, L. Stawiarz: None Declared