Development and psychometric evaluation of the self-assessment of psoriasis symptoms (SAPS) – clinical trial and the SAPS – real world patient-reported outcomes. (18th August 2017)

• Record Type: Journal Article
• Authors: Armstrong, April W.; Banderas, Benjamin; Foley, Catherine; Stokes, Jonathan; Sundaram, Murali; Shields, Alan L.
• Is Part Of: Journal of dermatological treatment. Volume 28:Number 6(2017)
• Page Start: 505
• Page End: 514
• Publication Date: 2017-08-18
• Subjects: PRO -- chronic plaque psoriasis -- instrument -- context of use -- qualitative -- psychometric; Skin -- Diseases -- Treatment -- Periodicals; Skin Diseases -- drug therapy -- Periodicals; Skin Diseases -- therapy -- Periodicals; 616.5
• DOI: 10.1080/09546634.2017.1290206
• Languages: English
• ISSNs: 0954-6634

Abstract

Abstract: Objective: The Self-Assessment of Psoriasis Symptoms – Clinical Trials (SAPS-CT) and SAPS – Real World (SAPS-RW) were simultaneously created to assess the experience of plaque psoriasis in two unique contexts. Methods: Qualitative and quantitative research was conducted in four phases namely concept elicitation, questionnaire construction, content evaluation and psychometric evaluation. Results: Following concept elicitation, 18 concepts were selected to inform questionnaire construction of the SAPS-CT and SAPS-RW. To accommodate each context of use, the SAPS-CT asks respondents to rate the target symptom 'at its worst' in the 24 h prior to assessment, while the SAPS-RW asks respondents to rate the target symptom "on average" in the 7 days prior to assessment. Cognitive debriefing confirmed that patients could comprehend and provide meaningful responses to both versions and, after minor modifications, resulted in 11-item questionnaires administered in an observational study ( N = 200). Results from the observational study informed further item reduction (SAPS-RW to six items and SAPS-CT to nine items) and demonstrated that scores from each were reliable (Cronbach's α > 0.90, test–retest intraclass correlation coefficient >0.70), construct valid and able to differentiate among clinically distinct groups. Conclusion: The SAPS-CT and SAPS-RW are content-valid PRO questionnaires capable of producing psychometrically sound scores when administered chronic to plaque psoriasis patients.