title: Ecological correlation between diabetes hospitalizations and fine particulate matter in Italian provinces.
abstract: BACKGROUND
  Exposure to particulate matter has been associated with increased risk of cardiovascular and respiratory diseases. We evaluated the ecological correlation between standardized hospital discharges with diabetes in Italian provinces and fine particulate matter (PM2.5) adjusting for common risk factors, socioeconomic factors and differences in hospitalization appropriateness.
  
  
  METHODS
  We used cross sectional data aggregated at the province level and available from official institutional databases for years 2008-2010. Covariates included prevalence of adult overweight, obese, smokers, physically inactive, education and income (as average gross domestic product per person, GDP). We reduced the number of covariates to a smaller number of factors for the subsequent statistical model by extracting meaningful components using principal component analysis (PCA). Log-linear multiple regression analysis was used to model diabetes hospital discharges with PCA components and PM2.5 levels and hospitalization appropriateness for men and women.
  
  
  RESULTS
  The first PCA components for both men and women were characterized by larger loadings of risk factors (obesity, overweight, physical inactivity, cigarette smoking) and lower socioeconomic factors (educational level and mean GDP). Diabetes hospitalization increases with the first PCA component and decreases with the index of hospitalization appropriateness. In fully adjusted models, diabetes hospitalizations increase with increasing annual PM2.5 concentrations, with a rise of 3.5 % (1.3 %-5.6 %) for men and of 4.0 % (1.5 %-6.4 %) for women per unit of PM2.5 increase.
  
  
  CONCLUSIONS
  We found a significant ecological relationship between sex and age standardised hospital discharge with diabetes as principle diagnosis and mean annual PM2.5 concentrations in Italian provinces, once that covariates have been accounted for. The relationship was robust to different means of estimating PM2.5 exposure. A large portion of the variance of diabetes hospitalizations was linked to differences of hospital care appropriateness between Italian regions and this variable should routinely be included in ecological analyses of hospitalizations.
authors.affiliation: Department of Public Health and Infectious Diseases, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy. angelo.solimini@uniroma1.it.
authors.forename: Angelo G
authors.initials: AG
authors.lastname: Solimini
authors.affiliation: Department of Public Health and Infectious Diseases, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy. ma.daddario@gmail.com.
authors.forename: Maddalena
authors.initials: M
authors.lastname: D'Addario
authors.affiliation: Department of Public Health and Infectious Diseases, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy. paolo.villari@uniroma1.it.
authors.forename: Paolo
authors.initials: P
authors.lastname: Villari
mesh_terms: D000328:Adult; D000393:Air Pollutants / Q000009:adverse effects*; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000209:etiology*; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D052638:Particulate Matter / Q000009:adverse effects*; D018570:Risk Assessment; D055815:Young Adult
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter