Reliability and validity of cutaneous sarcoidosis outcome instruments among dermatologists, pulmonologists, and rheumatologists

IMPORTANCE: Dermatologists, pulmonologists, and rheumatologists study and treat patients with sarcoidosis with cutaneous manifestations. The validity of cutaneous sarcoidosis outcome instruments for use across medical specialties remains unknown. OBJECTIVE: To assess the reliability and validity of cutaneous sarcoidosis outcome instruments for use by dermatologists and nondermatologists treating sarcoidosis. DESIGN, SETTING, AND PARTICIPANTS: We performed a cross-sectional study evaluating the use of the Cutaneous Sarcoidosis Activity and Morphology Instrument (CSAMI) and Sarcoidosis Activity and Severity Index (SASI) to assess cutaneous sarcoidosis disease severity and the Physician's Global Assessment (PGA) as a reference instrument. Four dermatologists, 3 pulmonologists, and 4 rheumatologists evaluated facial cutaneous sarcoidosis in 13 patients treated at a cutaneous sarcoidosis clinic in a 1-day study on October 24, 2014; data analysis was performed from November through December 2014. MAIN OUTCOMES AND MEASURES: Interrater and intrarater reliability and convergent validity, with correlation with quality-of-life measures as the secondary outcome. RESULTS: All instruments demonstrated excellent intrarater reliability. Interrater reliability (reported as intraclass correlation coefficient [95% CI]) was good for the CSAMI Activity scale (0.69 [0.51-0.87]) and PGA (0.66 [0.47-0.85]), weak for the CSAMI Damage scale (0.26 [0.11-0.52]), and excellent for the modified Facial SASI (0.78 [0.63-0.91]). The CSAMI Activity scale and modified Facial SASI showed moderate correlations (95% CI) with the PGA (0.67 [0.57-0.75] and 0.57 [0.45-0.66], respectively). The CSAMI Activity scale but not the modified Facial SASI showed significant correlations (95% CI) with quality-of-life instruments, such as the Dermatology Life Quality Index (Spearman rank correlation, 0.70 [0.25-0.90]) and the Skin Stigma raw score of the Sarcoidosis Assessment Tool (Pearson product moment correlation, 0.56 [0.01-0.85]). CONCLUSIONS AND RELEVANCE: The CSAMI and SASI were reliable and valid in assessing cutaneous sarcoidosis among our diverse group of specialists. The CSAMI Activity score also correlated with quality-of-life measures and suggested construct validity. These results lend credibility to expand the use of the CSAMI and SASI by dermatologists and nondermatologists in assessing cutaneous sarcoidosis disease activity.