Minimal Disease Activity and Anti-Tumor Necrosis Factor Therapy in Psoriatic Arthritis

ObjectiveA state of minimal disease activity (MDA) was defined and validated as target for treatment in psoriatic arthritis (PsA). We aimed to identify disease characteristics, outcome, and predictors of MDA in patients treated with tumor necrosis factor (TNF) blockers. MethodsPatients fulfilling the Classification of Psoriatic Arthritis criteria treated with TNF blockers were followed every 3-6 months. Patients were considered in MDA when they meet at least 5 of the 7 criteria. Sustained MDA was defined as an MDA state lasting 12 months. Patients achieving MDA were compared to non-MDA patients. A proportional odds discrete time survival analysis model was applied, adjusting for sex, age, PsA duration, abnormal erythrocyte sedimentation rate (ESR) and clinically damaged joint count at each visit to identify predictors for MDA. ResultsOf the 306 patients treated with TNF blockers identified from our database, 23 patients were in an MDA state when treatment was commenced; 57 were taking TNF blockers prior to enrollment. Therefore, 226 subjects were in a non-MDA state and constituted the study population. One hundred forty-five patients of 226 patients (64%) achieved MDA within a meanSD duration of 1.30 +/- 1.68 years. The mean +/- SD duration of MDA was 3.46 +/- 2.25 years. At total of 17 patients withdrew from therapy and remained in an MDA state. Male sex (odds ratio [OR] 1.65, 95% confidence interval [95% CI] 1.08-2.53; P=0.02) and normal ESR (OR 2.27, 95% CI 1.22-4.17; P=0.009) increased the odds for achieving MDA.Conclusion. MDA is achieved in 64% of patients treated with TNF blockers in a clinical setting. Male sex and normal ESR are predictors for MDA. On withdrawal or reduction in treatment, 11.6% of patients maintained MDA state.