Association of pruritus with sleep in patients with psoriasis and chronic spontaneous urticaria: A cross-sectional study.

Background:Pruritus is a frequent complaint associated with various inflammatory dermatoses. Sleep is often disturbed because of pruritus but the impact of severity and diurnal pattern of pruritus has not been studied so far. Objectives:To estimate the prevalence of nocturnal itch (NI) and its association with itch severity, sleep disturbance and quality of life (QoL) compared with non-NI in chronic plaque psoriasis (CPP) and chronic spontaneous urticaria (CSU). Methods:We performed a cross-sectional study in patients aged ≥18 years with CPP or CSU for at least 6 weeks. A comprehensive in-house questionnaire designed for study formed the basis for categorizing patients into NI and non-NI. Validated instruments like visual analog scale, pruritus grading system, General Sleep Disturbance Scale, and Dermatology life quality index were used to assess itch severity, sleep, and QoL. Results:A total of 255 patients (CPP: 131; CSU: 124) were included in this study. Prevalence of NI was 43.5% (95% confidence interval: 34.9%-52.4%) in CPP and 29% (95% confidence interval: 21.2%-37.9%) in CSU. NI was strongly associated with higher pruritus grading system scores in CSU and CPP (regression coefficient = 1.5, P =0.004 and regression coefficient = 1.3, P =0.004, respectively), with impaired sleep (OR = 2.97, P = 0.025) in CPP and with itch-affected sleep in CSU. Itch severity was associated with impaired sleep; however, the association was modified by the presence of NI in CSU patients. Conclusion:Nocturnal itch is prevalent in chronic dermatoses and significant for sleep deficit and impaired QoL. Early screening and management of sleep disturbance among patients presenting with nocturnal itch should be routinely undertaken.