Measuring disease activity in psoriatic arthritis.

Over the past decade, the assessment of the disease activity in psoriatic arthritis (PsA) has rapidly evolved in view of the need for valid, feasible, and reliable outcome measures that can be ideally employed in longitudinal cohorts, clinical trials, and clinical practice as well as the growing paradigm of tight disease control and treating to target in the management of PsA. This paper reviews the currently available measures used in the assessment of the disease activity in PsA. The composite measures for PsA that are under development are also discussed.