The relationship between patient acceptable symptom state and disease activity in patients with psoriatic arthritis

The Psoriatic Arthritis Disease Activity Score (PASDAS) and Disease Activity Index for Psoriatic Arthritis (DAPSA) are composite PsA disease activity measures. We sought to identify the PASDAS and DAPSA cut-off points consistent with patient acceptable symptom state (PASS), the threshold of symptoms beyond which patients consider themselves well, and examine PASS across published PASDAS and DAPSA thresholds for low, moderate and high disease activity.

We used a standard protocol including physician assessment and patient-reported outcomes to prospectively record measures required to calculate PASDAS and DAPSA. We identified PASS thresholds for the PASDAS and DAPSA using receiver operating characteristics curve analyses. We assessed the frequency of reporting acceptable symptom state across disease activity thresholds for PASDAS and DAPSA scores.

A total of 229 patients (58.5% male, mean age 55.5 years, mean disease duration 17.1 years) were recruited. The PASS threshold for the PASDAS was 3.79 [area under the curve (AUC) 0.86, sensitivity 0.75, specificity 0.82] and for the DAPSA was 11.10 (AUC 0.91, sensitivity 0.89, specificity 0.82). With the PASDAS, 90% of patients defined as having low disease activity considered their symptom state acceptable, compared with 55% and 17% among those with moderate and high disease activity, respectively. With the DAPSA, 98% of patients in disease remission considered their symptom state acceptable compared with 85, 22 and 18% among those with low, moderate and high disease activity, respectively.

We have defined PASS thresholds for PASDAS and DAPSA. The PASDAS target for low disease activity and DAPSA targets of low disease activity or remission align well with PASS.