Investigators Validate Disease Activity Score Measure for Psoriatic Arthritis

The Psoriatic Arthritis (PsA) Disease Activity Score (PASDAS) cutoff value can correctly define minimal disease activity among patients with PsA, according to research published in the Journal of Rheumatology.

Researchers sought to define a cutoff PASDAS that would effectively discriminate between patients in and not in a state of minimal disease activity. Additional goals of the study included defining PASDAS cutoff scores for the stricter definitions of low disease activity states. In total, 178 patients with PsA (53.9% men) were included in the current study, with a mean disease duration of 17.6±12.7 years.

Overall functional status was good, according to Health Assessment Questionnaire scores (0.53±0.59), as was self-reported quality of life. Overall PASDAS score was 3.29±1.29; 47.8% of participants were in a state of minimal disease activity.

Per receiver operating characteristic curve analyses, a PASDAS score of 3.2 was the point that maximized the sensitivity and specificity for minimal disease activity based on 5 of 7 criteria (sensitivity 88% [95% CI, 80%-93%]; specificity 92% [95% CI, 84%-96%]; area under the curve [AUC] 0.96 [95% CI, 0.94%-0.99]).

PASDAS scores of 2.6 and 2.1, respectively, maximized the sensitivity and specificity for minimal disease activity among those who met 6 of 7 and 7 of 7 criteria. For PASDAS 2.6, sensitivity was 88% (95% CI, 82%-93%), specificity was 86% (95% CI, 74%-93%), and AUC was 0.92 (95% CI, 0.88%-0.96%).

Similarly, for PASDAS 2.1, sensitivity was 89% (95% CI, 83%-93%), specificity was 81% (95% CI, 60%-92%), and AUC was 0.91 (95% CI, 0.86%-0.96%).

Researchers identified an increasing proportion of patients from low to high disease activity groups who required treatment escalation (increasing from 8.1% to 42% to 67%). Cochran-Armitage trend tests were used to demonstrate a statistically significant increasing trend of treatment escalation with increasing PASDAS cutoffs (P <.001).

Investigators noted that treating rheumatologists did not recommend treatment escalation in 52 patients with either moderate or high disease activity as defined by PASDAS. These patients had lower levels of the following measures: mean C-reactive protein, Physicians Global Assessment Visual Analogue Scale scores, swollen joint counts, and prevalence of dactylitis. They were also less likely to be treated with disease-modifying antirheumatic drugs compared with the 40 patients with PASDAS-defined moderate to high disease activity who were recommended for treatment escalation.

Study limitations included the use of only one visit to capture patients’ disease activity scores. Additionally, analyses were not conducted regarding the use of PASDAS to measure response to therapies.

The researchers of the study concluded, “Our study is the first to validate the PASDAS cutoff scores that were proposed to differentiate between low, moderate, and high disease activity in an independent and external dataset.”

Reference

Perruccio AV, Got M, Li S, et al. Treating psoriatic arthritis to target: Defining psoriatic arthritis disease activity score (PASDAS) that reflects state of minimal disease activity (MDA) [published online June 15, 2019]. J Rheumatol. doi: 10.3899/jrheum.181472