Background/Purpose: Treatment sustainability can measure drug effectiveness and encompasses drug effectiveness, safety, and compliance. Recent data suggest that differences in retention may exist between biologic agents even among the same class^1-3. However, the majority of data for real-world sustainability of biologics pertains to TNF-inhibitors. This analysis assessed the durability of treatment with the T cell co-stimulatory inhibitor abatacept in RA patients in Canadian routine practice and evaluated the determinants of treatment sustainability.

Methods: Data on RA patients administered abatacept in routine practice via the Orencia Response Program network, between August 2006 and February 2011 who had at least one follow-up evaluation, were included. Treatment sustainability was assessed with the Kaplan Meier (KM) estimator of the survival function. Parameters associated with treatment sustainability were assessed with multivariate Cox regression using a backwards selection method. Potential predictors considered were: number of previous biologics, monotherapy vs. combination therapy, home vs. clinic infusions, age, sex, severity of disease, presence of comorbidity, and years since diagnosis. The impact of these parameters on HAQ was assessed with mixed models with repeated measures.

Results: A total of 1,771 patients were included with mean (SD) age of 57.6 (13.2) years and duration since diagnosis of 16.5 (11.0). The majority (77.2%) were females. Overall, 672 (37.9%) patients  discontinued after a mean (SE) KM-based time to discontinuation of 26.8 (0.5) months. In multivariate survival analysis, increased number of previous biologics [HR_{1 vs. 0} (95% CI): 1.48 (1.14-1.19, P=0.004; HR_{≥2 vs. 0} (95% CI): 1.71 (1.34-2.18), P<0.001] and abatacept monotherapy [HR_{Mono vs. Combination} (95% CI): 1.23 (1.05-1.45), P=0.011] were associated with shorter duration of treatment while home infusions [HR_{Home vs. Clinic} (95% CI): 0.78 (0.67-0.93), P=0.004] and the presence of a comorbidity [HR_{Yes vs. No} (95% CI): 0.68 (0.58-0.80), P<0.001] were associated with increased treatment sustainability. When assessing the impact of these parameters on HAQ, only the number of previous biologics was identified as a significant predictor of lower response (P=0.009) after adjusting for potential confounders, with lower number of biologics being associated with improved response [B_{0 vs. ≥2} (SE): -0.12 (0.04), P=0.002; B_{1 vs. ≥2} (SE): -0.05 (0.03), P=0.167].

Conclusion: This real-world analysis identified the number of previous biologics, concomitant DMARD use, infusion location, and presence of comorbidity as independent predictors of abatacept treatment sustainability. The number of previous biologics may be associated with differences in effectiveness as measured by the HAQ whereas the other predictors may be associated with other reasons for discontinuation.

1. Neovius M et al. Ann Rheum Dis. 2013 Nov 27. Epub ahead of print.
2. Du Pan SM et al. Arthritis Rheum. 2009 May 15;61(5):560-8.
3. Frazier-Mironer A et al. Joint Bone Spine. 2014 Jul;81(4):352-9.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/predictors-of-real-world-treatment-sustainability-in-ra-patients-treated-with-abatacept-in-canada-implications-for-routine-care/