Methods of Outcomes Measurement in Nail Psoriasis

Background: Nail involvement is a common feature of psoriasis, predicting higher disease severity and greater impairment in quality of life. Valid assessment of nail psoriasis is relevant for research and routine clinical use. However, no measurement standards have currently been developed. Objective: To identify state-of-the-art outcomes measurements in nail psoriasis by literature analysis. Methods: Systematic Web-based literature search, followed by structured critical appraisal and consecutive descriptive report. The search focused on methodological and epidemiological publications and papers describing outcomes of clinical trials on nail psoriasis. Results: Initially, 646 publications met the primary criteria. After non-relevant or replicate publications were excluded, 66 papers were analysed, including clinical trials or case reports (n = 41), reviews (n = 11) and methodological or epidemiological studies (n = 14). In total, 23 clinical outcomes measures and 15 patient-reported outcomes (PRO) tools were used. None had been validated according to recent standards. In the studies with clinical interventions (n = 41), NAPSI (Nail Psoriasis Severity Index; n = 4) or target NAPSI (n = 2) were the most often used single tools, followed by Physician’s Global Assessment (n = 3). However, in 16 studies, no specifically described outcomes measures were used. Conclusion: Valid clinical outcomes measures in nail psoriasis are rare. Existing tools lack validation and standardisation. A need exists for accurate and scientifically sound evaluation of nail psoriasis severity in trials and clinical practice. To cover all elements of nail psoriasis, the optimal nail psoriasis assessment tool would include both PRO and physician-assessed outcomes measures