Construct validity and reliability of the Assessment of Systemic Sclerosis-Associated Raynaud's Phenomenon (ASRAP) questionnaire

Objectives: Assessment of construct validity and reliability of a novel patient-reported outcome (PRO) instrument for assessing the severity and impact of RP in SSc. Methods: An international multicentre study validation study of the 27-item Assessment of Systemic Sclerosis-Associated Raynaud's Phenomenon (ASRAP) and 10-item short-form (ASRAP-SF) questionnaires. The relationship between ASRAP questionnaires and demographics, clinical phenotype and legacy instruments for assessing SSc-RP severity, disability and pain was assessed. Repeatability was evaluated at 1 week. Anchor-based statements of health status facilitated assessment of ASRAP thresholds of meaning. Results: A total of 420 SSc subjects were enrolled. There was good correlation between ASRAP (and ASRAP-SF) with RP visual analogue scale (VAS) and Scleroderma Health Assessment Questionnaire RP VAS (rho range 0.648-0.727, P < 0.001). Correlation with diary-based assessment of SSc-RP attack frequency and duration was lower (rho range 0.258-0.504, P < 0.001). ASRAP questionnaires had good correlation with instruments for assessing disability, hand function, pain and global health assessment (rho range 0.427-0.575, P < 0.001). Significantly higher ASRAP scores were identified in smokers, patients with active digital ulceration (DU), previous history of DU and calcinosis (P < 0.05 for all comparisons). There was excellent repeatability at 1 week among patients with stable SSc-RP symptoms (intra-class coefficients of 0.891 and 0.848, P < 0.001). Patient-acceptable symptom state thresholds for ASRAP and ASRAP-SF were 45.34 and 45.77, respectively. A preliminary Minimally Important Clinical Difference threshold of 4.17 (95% CI 0.53, 7.81, P 1/4 0.029) was estimated. Conclusion: ASRAP and ASRAP-SF questionnaires are valid and reliable novel PRO instruments for assessing the severity and impact of SSc-RP.