Using qualitative methods to establish the clinically meaningful threshold for treatment success for the Severity of Alopecia Tool (SALT) score

Abstract Purpose: Traditionally, appropriate anchors are used to investigate the amount of change on a clinician-reported outcome assessment that is meaningful to individual patients. However, novel qualitative methods can additionally inform the individual improvement threshold for demonstrating the clinical benefit of new treatments. This study aimed to establish a clinically meaningful threshold for treatment success for the clinician-reported Severity of Alopecia Tool (SALT) score for patients with alopecia areata (AA).Methods: A purposive sample of 10 dermatologists expert in the treatment of AA, and 30 adult and adolescent patients with AA and a history of ≥50% scalp hair loss were recruited. Semi-structured interview questions explored thresholds that represented treatment success to clinicians and patients with AA. Findings were analyzed using thematic methods to identify treatment success thresholds.Results: Expert clinicians considered a static threshold of 80% (n=5) or 75% (n=3) of the scalp hair as a treatment success. Patient responses ranged from 70 - 90% (median 80% of the scalp hair). Subsequently, queried patients confirmed that achieving SALT score ≤20 with treatment would be a success. Reflections on the methodology include: clinician perceptions can be informed by current clinical practice and knowledge of existing treatments and research and clinicians easily identified thresholds through qualitative discussions; patients were able to understand and identify thresholds for improvement less than complete absence of disease. Conclusions: This qualitative investigation of expert clinicians and patients with AA confirmed that achieving an amount of 80% or more scalp hair (SALT score ≤20) was an appropriate individual treatment success threshold indicating clinically meaningful improvement for patients with ≥50% scalp hair loss. A qualitative investigation of a quantifiable treatment success is possible through well-designed interview questions for the indication and patient population. Both clinician and patient input plays a critical role in understanding the clinical benefit meaningful to patients.