Background: Itch is a symptom with significant physical, psychological, and financial burden worldwide. Symptom-specific and demographic risk factors have been published although community-level risk factors have not been thoroughly studied. Objectives: To describe the epidemiological risk factors of itch and to present a hypothesis that can account for these trends. Materials and methods: Itch incidence, prevalence, and years lost to disability (YLD) by age, sex, world region, socio-demographic index, percent of population using basic sanitation services, mortality due to air pollution, and gross domestic product (GDP) per capita were obtained from the University of Washington Institute for Health Metrics and Evaluation Global Burden of Disease (GBD), World Health Organization Global Health Observatory (WHO GHO), and Worldometer databases. Linear regression models were utilized to analyze the relationship of sanitation, air pollution, and GDP with itch incidence, prevalence and YLD. Results: Female sex and age were positively associated with higher incidence of itch. The percent of population using basic sanitation services was also positively correlated with itch incidence, prevalence, and YLD (P<0.001). Mortality rate due to air pollution was negatively associated with itch incidence, prevalence, and YLD (P<0.001). However, GDP per capita was not associated with the incidence (P=0.5), prevalence (P=0.8), and YLD (P=0.7) of itch. Conclusions: The “hygiene hypothesis” might explain global trends of itch as more industrialized countries have higher itch incidence rates. Thus, approaches which target molecular pathways involved in the “hygiene hypothesis” may lead to a decreased global itch burden.

Journal of Medical Internet Research - International Scientific Journal for Medical Research, Information and Communication on the Internet #Preprint #PeerReviewMe: Warning: This is a unreviewed preprint. Readers are warned that the document has not been peer-reviewed by expert/patient reviewers or an academic editor, may contain misleading claims, and is likely to undergo changes before final publication, if accepted, or may have been rejected/withdrawn. Readers with interest and expertise are encouraged to sign up as peer-reviewer, if the paper is within an open peer-review period. Please cite this preprint only for review purposes or for grant applications and CVs (if you are the author). N/A

Background: Dermatological conditions, especially when severe, can lead to sleep disturbances that affect a patient’s quality of life. However, limited research exists on the efficacy of treatments for improving sleep parameters in skin conditions. Objective: The objective was to perform a systematic review of the literature on dermatological conditions and the treatments available for improving sleep parameters. Methods: A literature review was performed using the PubMed, Ovid MEDLINE, Embase, Cochrane, and ClinicalTrials.gov databases from 1945 to 2021. After filtering based on our exclusion criteria, studies were graded using the SORT (Strength of Recommendation Taxonomy) algorithm, and only those receiving a grade of “2” or better were included. Results: In total, 25 treatment studies (n=11,025) assessing sleep parameters related to dermatological conditions were found. Dupilumab appeared to be the best-supported and most effective treatment for improving sleep in atopic dermatitis (AD) but had frequent adverse effects. Topical treatments for AD were mostly ineffective, but procedural treatments showed some promise. Treatments for other conditions appeared efficacious. Conclusions: The evaluation of sleep parameter changes in dermatological treatments is predominantly restricted to AD. Systemic interventions such as dupilumab and procedural interventions were the most efficacious. Sleep changes in other dermatoses were limited by a paucity of available studies. The inclusion of a sleep assessment component to a broader range of dermatological treatment studies is warranted.