Association of uremic pruritus in hemodialysis patients with the number of days of high mean 24-hour particulate matter with a diameter of <2.5 μm

Uremic pruritus (UP) is a common and incapacitating symptom in patients undergoing hemodialysis (HD). The pathogenesis of UP is multifactorial and complex. Particulate matter (PM), a major air pollutant, is a mixture of particles with various chemical compositions. PM is associated with several allergic diseases, including dermatitis. To assess the role of PM (PM with a diameter of <10 μm [PM(10)] and PM with a diameter of <2.5 μm [PM(2.5)]) and other clinical variables in UP in patients on HD, we recruited 866 patients on maintenance HD (MHD). We analyzed the number of days of mean 24-hour PM(10) ≥125 μg/m(3)/12 months (NDPM(10)) or the number of days of mean 24-hour PM(2.5) ≥35 μg/m(3)/12 months (NDPM(2.5)) exceeding the standard level in the past 12 months respectively to determine the association with UP. In a multivariate logistic regression, HD duration, serum ferritin levels, low-density lipoprotein (LDL) levels, and NDPM(2.5) ≥116 days/12 months were positively associated with UP. This cross-sectional study showed that the number of days on which the environmental PM(2.5) exceeds the standard level might be associated with UP in patients on MHD.