Background/Purpose: Abatacept is a biological T-cell modulation therapy used in RA. Data on diagnosis, preceding treatment as well as the reason for the discontinuation of the preceding treatment was derived from the Swedish Rheumatology Quality Registry.
Method: Observational data from the Swedish Rheumatology Quality Registry was collected for the period from April 2006 to May 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 (all strata) with Tukey-Kramer multiple-comparison adjustments were made.
Results: There were 606 patients started abatacept treatment from Apr 2006 to Dec 2010. Regarding the 473 RA patients (367 females or 78%), median and interquartile range of age at start of abatacept was 60 years (52-66) and median disease duration was 11 years (6-19). Median time since first given biological treatment to abatacept start was 3.3 years (1.3-6.3).
Abatacept was given as first biological treatment in 44 patients (9%), after one or two previous biological treatments in 263 (55%) patients, after three or more biological treatments in 167 (36%). Survival probability of abatacept in these groups is shown in Figure 1. After 1, 2 and 3 years drug survival was 78%, 70% and 57% respectively in bio-na´ve patients, 64%, 50% and 49% in patients with 1-2 previous biological treatment and 57%, 41% and 29% in patients with 3 or more previous biological treatments. Bio-na´ve patients had significantly longer drug survival time than patients with 3 or more previous treatments (p=0.0065), and patients with 1-2 previous biological treatments had longer drug survival time than patients with 3 or more previous treatments.
DAS28 was measured 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 in DAS28 was significantly better in men than in women at all time points except for 6 months. There was a significant tendency towards a longer drug survival in men compared to women (p=0.05). At 1, 2 and 3 years respectively drug survival was 69%, 57%, 52% in men and 61%, 46%, 37% in women.
Conclusion: In this cohort of 473 RA patients starting abatacept treatment during a time period of four years, drug survival time was longer for bio-na´ve patients compared to patients treated with previous biological drugs. There was seen a gender difference in abatacept treatment outcome in favour of men.
Figure 1. Abatacept survival probability of bio-na´ve RA patients, patients with 1-2 previous, and
≥3 previous biological drugs. The small vertical bars on the curves indicate censored cases.
Disclosure: R. Nisell, None; L. Stawiarz, None; S. Lindblad, None.