Validation of the Peak Pruritus Numerical Rating Scale. (1st October 2019) - Yosipovitch, G.
Summary: Atopic dermatitis (AD) is a chronic skin disease occurring in about 5 to 10% of adults worldwide. It can cause intense and persistent itch. For almost two‐thirds of patients with moderate‐to‐severe AD, the itching lasts at least 12 hours a day, and is severe to unbearable. In clinical trials that are looking at how effective a treatment for AD is, itch intensity must be measured. Given itch is subjective, its intensity is most accurately reported by patients themselves. In this study, investigators from the U.S.A. and Europe developed a scale of itch called the Peak Pruritus Numerical Rating Scale (NRS). The scale measures the worst itch (peak pruritus) during the past 24 hours by asking patients "On a scale of 0 to 10, with 0 being 'no itch' and 10 being 'worst itch imaginable', how would you rate your itch at the worst moment during the previous 24 hours?". To ensure the scale is reliable and valid (i.e., appropriate for assessing itch in AD patients), patients were interviewed about their opinions of the scale. The scale was then implemented in three large clinical trials of adults with moderate‐to‐severe AD. Interviewed patients said that the scale provided a relevant, clear, and comprehensive assessment of itch severity. As hypothesized, scores from the Peak Pruritus NRS showed moderate‐to‐strong correlation with other measures of itch, and weak‐to‐moderate correlation with measures of AD signs (clinical symptoms). The investigators concluded that the Peak Pruritus NRS is a well‐defined, reliable, sensitive, and valid scale for evaluating worst itch intensity in adults with moderate‐to‐severe AD.