Background Clinical trials performed in RA patients with anti-TNFa therapy lead to demonstrate the superiority of DMARDs association strategy over biologic monotherapy. Accordingly, the association Methotrexate-bioDMARD became the gold standard of biological treatment for RA patients. Nevertheless, various registries have shown that, in daily practice, most biologics are used as monotherapy in about 30% of RA patients. Thus, it seems to be important to improve our knowledge on the impact of the use of biological treatments as monotherapy.
Objectives The aim of this study was to assess the maintenance rate and efficacy of Abatacept (ABA) in monotherapy compared to ABA + conventional synthetic DMARD (csDMARD) after 6 months (M6) in RA patients using data from the ORA registry.
Methods Patients were recruited according inclusion criteria of ORA registry: adult patients affected by RA according to ACR 1987 criteria and treated with ABA. Exclusion criteria were missing data for therapeutic response or maintenance. The maintenance rate was analysed in two steps: 1) classical analysis of ABA maintenance rate, comparing the patient group in which ABA was initiated as monotherapy to the group in which ABA was initiated in combination with csDMARD; 2) Evaluation of the maintenance rate of therapeutic strategies: ABA monotherapy vs. ABA + csDMARD, any change of csDMARD treatment nature being considered as failure of retention. Efficacy of therapeutics was defined according to EULAR response criteria. Statistical analyses used Chi-2 test to compare the two groups of patients, or Fisher exact test if needed. A statistical threshold of 0.05 was chosen.
Results The maintenance rate after 6 months of treatment was evaluated within 569 patients. No significant difference was found in ABA maintenance rate between ABA initiated as monotherapy and ABA + csDMARD (75% (142/188) vs. 76% (291/381) respectively, p=0.824). However, a significant difference was observed in maintenance rate of therapeutic strategy in ABA initiated as monotherapy compared to ABA + csDMARD (58.5% (110/188) vs. 68% (258/381) respectively, p=0.031). Among patients in whom ABA was initiated as monotherapy, a csDMARD was secondarily associated to ABA in 16.5% of patients within the first 6 months of treatment.
Data on ABA efficacy were available for 444 patients. There was no significant difference of proportion of responders after a 6-months treatment between ABA monotherapy compared to ABA + csDMARD (60.2% (88/146) vs. 60% (179/298) respectively, p=0.967).
Conclusions This work represents the first study comparing Abatacept monotherapy and ABA combined with csDMARD. Data from the French national registry ORA allowed to perform a “real-life” analysis relevant for bedside practice, even if radiological data are needed to evaluate structural modifications. ABA can be used as monotherapy with satisfactory effectiveness and maintenance, providing an acceptable alternative when csDMARDs are undesirable. Nonetheless, this treatment strategy exposes the rheumatologist to add a csDMARD in a high proportion of patients during the first 6 months.
Disclosure of Interest None declared