Clinical and ultrasonographic predictors of disease activity after TNF-α inhibitor spacing in patients with psoriatic arthritis.

Objective: Dose reduction of biologic drugs in patients with psoriatic arthritis (PsA) who are in Minimal Disease Activity (MDA) is now considered a feasible option. This study evaluated which baseline clinical and ultrasonographic (US) factors may be predictive of disease activity after anti-TNF-α spacing.

Methods: This observational, prospective, multicentre, 12-month study enrolled consecutive adult patients with PsA taking TNF-α inhibitors and in stable MDA who accepted to reduce their dose therapy by doubling the administration interval. Data collection included demographics, personal history, clinical disease characteristics, and joints and entheses US features. Patients maintaining the MDA were compared with those who experienced a disease flare during the 12 months of follow-up. The statistical analysis included the comparison between groups and the search of the factors associated with persistence of MDA.

Results: Of the evaluable 72 patients (29 females and 43 males), 55 (76.4%) maintained a state of MDA while 17 (23.6%) experienced a disease relapse. Baseline values of DAPSA<2 and of BASDAI<1.5, and lower BASDAI and DAS28 values were significantly associated with maintenance of MDA. The multivariate analysis showed that baseline values of DAPSA<2 and of BASDAI<1.5 were predictive of persistence of MDA. Baseline US findings were not associated with the outcome of disease activity.

Conclusions: In this study, anti-TNF-α spacing proved to be feasible in most of the PsA patients in a stable MDA. The only factor predictive of persistence of remission was a very low clinical disease activity at baseline.