Cross-sectional retrospective study of difficult-to-treat rheumatoid arthritis patients followed up at Hacettepe University Hospital

Rheumatoid arthritis (RA) is a chronic rheumatic disease characterised by progressive joint damage and extra-articular symptoms. Despite the numerous treatment options currently available, remission or low disease activity cannot be achieved in some patients. For these patients, the European League Against Rheumatism (EULAR) established the definition of Difficult to Treat RA (D2T-RA) in 2021. The objective of this study was to determine the frequency of D2T-RA in RA patients using b/tsDMARD in our centre and to identify the risk factors predicting D2T RA at the time of b/tsDMARD initiation. The study included RA patients using b/tsDMARD who applied to the outpatient clinic of Hacettepe University Department of Internal Medicine, Division of Rheumatology between 1 April 2023 and 30 November 2023. The electronic system was used to analyse laboratory, examination notes, medication information and demographic characteristics. Patients were divided into two groups as patients with and without D2T according to the criteria. The characteristics of the patients at the time of the study visit and at the start of b/tsDMARD treatment were compared between the two groups. Of the 487 RA patients included in the study, 181 (37.1%) fulfilled the D2T- RA criteria. There was no difference in the treatments used before b/tsDMARD initiation. Hypertension (48.6% vs. 30.4%; p< 0.001) and coronary artery disease (11% vs. 3.9%; p= 0.017) were more common in patients with D2T-RA compared to those without. The mean BMI at the time of b/tsDMARD initiation was significantly higher in D2T-RA patients than in non-D2T-RA patients (29.8 kg/m2 vs. 28.6 kg/m2; p=0.02). Furthermore, the DAS28-ESH values at the time of b/tsDMARD initiation were significantly higher in D2T-RA patients than in non-D2T-RA patients. In univariate and multivariate analyses, a HAQ score ≥ 1 at b/tsDMARD initiation was identified as a factor for D2T-RA (OR 2.08 (1.17-3.69), p= 0.012). Despite the availability of new, improved treatment options for rheumatoid arthritis (RA), many patients still do not achieve remission or low disease activity. The identification of patients with D2T-RA and associated factors will facilitate the management of these patients. Further studies on this subject are required.