Validation and response to treatment of a pruritus self-assessment tool in patients with moderate to severe psoriasis

BackgroundPruritus is a common symptom of psoriasis. In many clinical trials of psoriasis treatments, severity of pruritus is a patient-reported outcome.ObjectiveWe sought to evaluate a patient-reported pruritus self-assessment tool using data from clinical trials of a tumor necrosis factor blocker.MethodsThe validity of the patient-reported 6-point pruritus assessment tool (0 = none to 5 = severe) was determined using data from a phase III trial of etanercept, a tumor necrosis factor blocker. The performance of the pruritus assessment tool was then evaluated using data from two large etanercept trials.ResultsThe pruritus assessment tool was validated and deemed to have good test-retest reliability (kappa coefficient = 0.71; 95% confidence interval = 0.62-0.80) and responsiveness (standardized response mean = 1.28; effect size = 1.63, responsiveness statistic = 1.54). Improvements in pruritus scores correlated with improvements in Psoriasis Area and Severity Index after 8 weeks of etanercept therapy in two phase III trials.LimitationsThe pruritus assessment is validated only for patients with moderate to severe plaque psoriasis, and may not be applicable to other patient populations.ConclusionsThe pruritus assessment tool is a valid measurement of pruritus intensity in patients with moderate to severe plaque psoriasis and can discriminate between patients on and off treatment.