The Psoriatic Arthritis Impact of Disease (PsAID) questionnaire is a reliable, feasible, and discriminative patient-reported outcome measure (PROM) with utility among patients with psoriatic arthritis in clinical practice, according to the results of a prospective, single-center Australian cohort study published in the Annals of the Rheumatic Diseases.
The investigators of the study sought to evaluate the validity of the PsAID in an independent cohort of patients, estimate the minimally important difference needed for improvement, and explore the potential use of the individual components of the PsAID in clinical practice. Construct validity was measured by Spearman correlation (r) with other PROMs, and reliability was assessed by intraclass correlation coefficient at 1 week. Sensitivity to change at 3 months was established by the standardized response mean in individuals with active disease who required a switch in therapy.
A total of 129 patients completed the baseline questionnaires and assessments. Mean patient age was 52.1±13.3 years, and 57% of the patients were women. Mean disease duration was 10.2±7.8 years. The mean PsAID12 score, which uses all 12 domains of health and well-being, including fatigue, functional capacity, sleep, and coping, was 3.92±2.26, with an intraclass correlation coefficient of 0.91 (95% CI, 0.87-0.94). The standard error of measurement was 0.51 and the minimal detectable change was 1.41.
Strong correlation (r≥0.70) was reported with most of the PROMs analyzed, and there was moderate correlation with the clinical outcomes of tender and swollen joint counts (r=0.57 and 0.40, respectively). In addition, the standardized response mean of the PsAID12 was 0.74 (95% CI, 0.45-0.97). Strong correlation was demonstrated with individual PsAID items and their corresponding PROM questionnaires (r≥0.67).
The investigators concluded that the PsAID is a valid measure of the effect of disease in patients with psoriatic arthritis. It can be used in patients with both stable and active disease, correlates well with clinical outcome measures and PROMs, and can help tailor treatment to individual patients.
Holland R, Tillett W, Korendowych E, et al. Validation of the Psoriatic Arthritis Impact of Disease (PsAID) Questionnaire and its potential as a single-item outcome measure in clinical practice [published online November 16, 2017]. Ann Rheum Dis. doi: 10.1136/annrheumdis-2017-211996