Search for predictors of achieving minimal disease activity during tofacitinib therapy in patients with psoriatic arthritis

Abstract

Objective: to search predictors of achieving minimal disease activity (MDA) during therapy in patients with psoriatic arthritis (PsA).Materials and methods. The study included 41 patients, predominantly men (58.9 %), with a confirmed PsA diagnosis and a disease duration of at least 6 months. In all cases, the diagnosis fulfilled the CASPAR criteria. The mean age of the patients at the time of enrolment in the study was 43.0±10.1 years, the duration of PsA was 7.7±7.1 years, the duration of psoriasis was 18.6±10.4 years, and the DAPSA index was 44.2±17.1. All patients were prescribed tofacitinib at a dose of 5 mg twice daily, followed by a possible dose increase to 10 mg twice daily. In addition to a general clinical examination and a standard rheumatological examination, the level of secreted DKK-1 protein and health-related quality of life (HRQoL, using a special PsAID-12 questionnaire) were determined. Multivariate stepwise discriminant analysis was used to search for predictors for the achievement of MDA in patients with PsA and to calculate the coefficients.Results and discussion. Based on the results obtained, a predictor for the achievement of MDA (PMDA) was developed: PMDA=-1.165 × number of inflamed entheses + DKK-1 level (pmol/l) + 3.086 × PsAID-12 “Skin lesions” scale value (if this indicator was ≤3 points, it was assigned a value of 1, if it was >3 points – 0) + 2.568 × PsAID-12 “Pain” scale (if this indicator was ≤6 points, it was assigned a value of 1, if it was >6 points – 0).The ROC analysis, which reflects the prognostic significance of this index, showed AUC (area under the curve) of 0.803 (95% confidence interval 0.739–0.867; p=0.02). PMDA=3.89 was chosen as the cut-off value; the sensitivity of this indicator was 91 %, the specificity – 79 %. Therefore with a PMDA ≥3.89, the probability of the patient achieving a MDA after 3 months is high; with a PMDA ˂ 3.89, it is low.Conclusion. We identified factors influencing the achievement of MDA in patients with PsA and developed a mathematical model. It allows timely assessment of the quality of treatment and its correction if necessary, thereby slowing disease progression.