Background Abatacept is a biological anti-rheumatic drug used in Rheumatoid Arthritis (RA). Data on patient characteristics, diagnosis, preceding treatment and outcomes of abatacept have been collected in the Swedish Rheumatology Quality register (SRQ) which comprises the ARTIS register, since the drug was approved in 2006.
Objectives To evaluate drug survival probability of abatacept in clinical practice for patients with RA, using a national register.
Methods Observational data from the SRQ were collected for the period from April 1st, 2006 to June 30th, 2012. True retention rates and survival analysis (Kaplan Meier) with right censoring and log-rank test of equality across strata were performed and Šidák multiple-comparison adjustments applied.
Results 815 RA patients (637 females, 78%) started abatacept treatment between April 2006 and June 2012 (78% of total 1051 registered patients treated with abatacept). The median (IQR) age at start of abatacept was 61 years (52-67) and the median (IQR) duration of RA was 11.4 years (6.0-19.8). In patients with previous biological treatment, median time from start of first biological treatment to abatacept start was 3.4 years (IQR 2.4-7.9). Median follow-up on abatacept was 0.9 years (IQR 0.4-1.9).
Abatacept was prescribed as the first biological treatment in 99 RA patients (12%), after one previous and unique biological drug in 219 (27%) patients, and after two or more unique biological drugs in 497 (61%) patients. Bio-naïve patients had significantly longer drug survival time than patients with two or more previous treatments (p=0.02) (Table 1).
The overall retention rate at 6 months was 79% (582 of totally 735 patients which had been followed for at least 6 months after the start of abatacept treatment). The retention rate for patients receiving abatacept in the bio-naïve group was higher (94%, 77 of 82) compared with those who received abatacept after one (78%, 152 of 196) or ≥2 previous biological drugs (77%, 353 of 457). At 1 year follow-up, the overall retention rate was 56% (373 of 670) and 33% at 2 years follow-up (189 of 575).
A longer drug survival was also found also in men compared to women (p=0.0008). From 1 to 5 years, drug survival was respectively 68%, 55%, 50%, 45% and 45% in men, and 56%, 39%, 31%, 28% and 22% in women. The retention rate at 6 months was higher in men (83%, 129 of 155), compared with women (78%, 451 of 580).
Conclusions In this nationwide cohort of RA patients starting abatacept treatment, both retention rate and drug survival time was longer for bio-naïve patients compared to patients previously treated with ≥2 biological drugs. A gender difference in favour of men was also seen for drug survival and retention rate.
Disclosure of Interest None Declared
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