Background/Purpose: The adherence to the therapeutic regimen in patients with Rheumatoid Arthritis (RA) varies between 30 and 80%. Classically, it is mentioned that the adherence to intravenous medication (IV) may be better than oral or subcutaneous, however there are few studies that analyzed it. Objective: To evaluate the adherence to biological (-b)DMARDs IV in patients with RA in clinical practice and to determine the factors that could have an impact on the adherence.

Methods: Observational study. Patients ≥18 years of age, with a diagnosis of RA according to ACR/EULAR 2010 criteria, who received at least 3 infusions of the b-DMARD IV abatacept (ABA) and/or tocilizumab (TCZ), during the course of their illness. Medical records, were reviewed to collect: sociodemographic data, clinical characteristics of the disease, comorbidities, disease activity, functional capacity by HAQ. Information was obtained on previous and concomitant treatments for b-DMARD, including steroids and conventional (-c) DMARDs, number of infusions of b-DMARD received, date of their initiation and discontinuation and causes of suspension. Adherence was calculated as the number of infusions received during the treatment period, considering a 28 days interval between infusions as optimal. Statistical analysis: descriptive statistics, Chi2 test or Fisher’s exact test, Student’s T test and Mann Whitney test. Multiple logistic regression model to evaluate predictors of good adherence (≥80%).

Results: 67 patients were included, 94% were women, with a median disease duration of 13.8 years (IQR 8-18,2). 82.1% (55 patients) had medical coverage, 60% corresponded to social work. The median distance to the infusion center was 15 km (IQR 6.5-27). As a concomitant treatment, 72.4% received c-DMARD (without significant differences between ABA and TCZ), 52.7% prednisone and 64.3% NSAIDs. After 3 months of treatment, the baseline DAS28 decreased from 5.46 (IQR 4.77- 5.99) to 3.87 (IQR 2.79-4.68), p < 0.001, and the baseline HAQ-A from 2 (IQR 1.5-2) to 1 (IQR 1-2), p< 0.001. After a median follow-up time of 2.42 years (IQR 1.2-4.7), 38 patients (56.5%) discontinued definitively the b-DMARD IV. The most frequent causes of suspension were inefficiency in 62.9%, AE in 20% and lack of provision in 14.3%. The median survival was 4 years, without significant differences between ABA and TCZ. The median number of infusions per year was 10.17 (IQR 8.3-10.9), equivalent to an adherence of 78.2%, considering as an optimum of 13 infusions/year. Excluding suspension of b-DMARD IV by AE and/or surgeries, the median number of infusions per year was 10.8 (IQR 9.3-11.6), equivalent to an adherence of 83.1%. The median infusions/year correlated negatively with the distance to the infusion center (Rho: – 0.27, p = 0.003) and was significantly lower in patients without health coverage (8.5 ±2.5 vs 10.7 ±1.5, p < 0.001). In the multivariate analysis, having health coverage was the only variable that remained associated with better adherence ≥80% (OR: 6.27, 95% CI 1.1- 37.9, p = 0.04).

Conclusion: Adherence to treatment with b-DMARD IV was acceptable, however our patients lose, on average of 3 infusions per year. The only independent predictor associated with good adherence was having health coverage.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/adherence-to-treatment-with-intravenous-biological-agents-in-patients-with-rheumatoid-arthritis/