Objective: to study the timing of the onset and duration of remission and MDA after BA initiation and discontinuation in patients with early PsA, followed up according to the Treat-to-Target (T2T) principles.

Subjects and methods. The investigation enrolled 34 patients (18 men, 16 women) with early PsA who met the CASPAR criteria, had participated  in the All-Russian Registry and followed up according to the T2T principles.The patients' mean age was 38±11 years; the duration of PsA and psoriasis was 12.0±10.0 and 89.8±91.1 months, respectively. At the beginning of the follow-up, the median DAS and DAPSA scores were 4.05 [3.72; 5.10] and 33.55[28.34; 41.77], respectively. All the patients were prescribed BAs (adalimumab  (n=21), ustekinumab  (n=8), certolizumab  pegol (n=3)  or etanercept (n=2)) in combination  with methotrexate. The median therapy duration was 9 [6.5; 15] months. The activity of the disease and efficiency of PsA therapy were evaluated using DAS, DAPSA and the criteria for MDA (tender joint count of ≤1, swollen joint count of ≤1, PASI score ≤1 or BSA ≤3, pain intensity on visual analogue scale (VAS) ≤15 mm, patient's assessment of disease activity on VAS ≤20 mm; HAQ score ≤0.5; enthesitis index ≤1) at the beginning of the investigation and then every 3 months. The number of patients who had achieved remission (DAS <1.6; DAPSA ≤4) or MDA (5 of 7 criteria) during BA therapy at least once during the 24-month follow-up was determined.  The absence of remission or MDA at the time of examination  was considered to be an exacerbation. The duration of remission and MDA was estimated after BA discontinuation according to the activity indices at the time of examination  by a physician every 3 months.

Results and discussion. During the 24-month follow-up, DAS/DAPSA  remissions were achieved at least once by 28 (82%)/27 (79%) patients, respectively; and MDA was seen in 28 (82%). The first DAS/DAPSA  remission occurred after an average of 4.8±2.2/5.8±3.2 months; MDA – after 4.0±1.9 months. The average DAS/DAPSA  remission duration was 9.1±5.0/8.3±5.0 months,  respectively, and MDA – 11.0±5.5 months. Seven (21%) patients responded to therapy, but did not achieve neither DAPSA, nor DAS remission and 6 (18%) patients did not have MDA. 8 patients in remission continued  to receive BAs until the end of the follow-up. Nineteen  patients discontinued therapy for various reasons. After discontinuation of BAs, the physician recorded DAS exacerbation in 11 (55%) patients after an average of 6.5±2.3 months and DAPSA exacerbation in 12 (60%)after 5.8±2.3 months. According to the patient assessment, an exacerbation developed in an average of 3.5±3.4 months after BA discontinuation. A DAS/DAPSA  exacerbation was observed in 5 (15%) patients during BA therapy after an average of 11.5±4.7/12.0±4.7 months.

Conclusion. During BA therapy, the majority of patients with early PsA achieved remission and MDA following an average of 5 months after the start of treatment using the T2T strategy. After BA discontinuation, an exacerbation occurs in more than half of patients. Following BA discontinuation, the remission duration recorded by the physician according to the activity indices averages 6 months; the duration of subjective improvement  according to the patient assessment was 3 months. With continued  BA treatment, 15% were observed to have lost its efficiency after an average of 12 months.