title: Cardiorespiratory treatments as modifiers of the relationship between particulate matter and health: a case-only analysis on hospitalized patients in Italy.
abstract: BACKGROUND
  A few panel and toxicological studies suggest that health effects of particulate matter (PM) might be modified by medication intake, but whether this modification is confirmed in the general population or for more serious outcomes is still unknown.
  
  
  OBJECTIVE
  We carried out a population-based pilot study in order to assess how pre-hospitalization medical treatments modify the relationship between PM<10 μm in aerodynamic diameter (PM10) and the risk of cardiorespiratory admission.
  
  
  METHODS
  We gathered information on hospitalizations for cardiorespiratory causes, together with pre-admission pharmacological treatments, that occurred during 2005 in seven cities located in Lombardy (Northern Italy). City-specific PM10 concentrations were measured at fixed monitoring stations. Each treatment of interest was analyzed separately through a case-only approach, using generalized additive models accounting for sex, age, comorbidities, temperature and simultaneous intake of other drugs. Analyses were stratified by season and, if useful, by age and sex.
  
  
  RESULTS
  Our results showed a higher effect size for PM10 on respiratory admissions in subjects treated with theophylline (Odds Ratio (OR) of treatment for an increment of 10 μg/m(3) in PM10 concentration: 1.119; 95% Confidence Interval (CI): 1.013-1.237), while for cardiovascular admissions treatment with cardiac therapy (OR: 0.967, 95% CI: 0.940-0.995) and lipid modifying agents (OR: 0.962, 95% CI: 0.931-0.995) emerged as a protective factor, especially during the warm season. Evidence of a protective effect against the pollutant was found for glucocorticoids and respiratory admissions.
  
  
  CONCLUSIONS
  Our study showed that the treatment with cardiac therapy and lipid modifying agents might mitigate the effect of PM10 on cardiovascular health, while the use of theophylline seems to enhance the effect of the pollutant, possibly due to confounding by indication. It is desirable to extend the analyses to a larger population.
authors.affiliation: Research Centre on Public Health. Department of Statistics and Quantitative Methods. University of Milano - Bicocca. Via Cadore 48, I-20052 Monza, (MB), Italy. Electronic address: sara.conti@unimib.it.
authors.forename: Sara
authors.initials: S
authors.lastname: Conti
authors.affiliation: School of Hygiene and Preventive Medicine. Department of Health Sciences. University of Milano - Bicocca. Via Cadore, 48, I-20052 Monza, (MB), Italy. Electronic address: lafranconi.ale@gmail.com.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Lafranconi
authors.affiliation: Department of Environmental Health, Harvard School of Public Health, P.O. Box 15698, Landmark Center-415-K, Boston, MA 02215, USA. Electronic address: azanobet@hsph.harvard.edu.
authors.forename: Antonella
authors.initials: A
authors.lastname: Zanobetti
authors.affiliation: Research Centre on Public Health. Department of Statistics and Quantitative Methods. University of Milano - Bicocca. Via Cadore 48, I-20052 Monza, (MB), Italy. Electronic address: carla.fornari@unimib.it.
authors.forename: Carla
authors.initials: C
authors.lastname: Fornari
authors.affiliation: Research Centre on Public Health. Department of Statistics and Quantitative Methods. University of Milano - Bicocca. Via Cadore 48, I-20052 Monza, (MB), Italy. Electronic address: fabiana.madotto@unimib.it.
authors.forename: Fabiana
authors.initials: F
authors.lastname: Madotto
authors.affiliation: Department of Environmental Health, Harvard School of Public Health, P.O. Box 15698, Landmark Center-415-K, Boston, MA 02215, USA. Electronic address: joel@hsph.harvard.edu.
authors.forename: Joel
authors.initials: J
authors.lastname: Schwartz
authors.affiliation: Research Centre on Public Health. Department of Statistics and Quantitative Methods. University of Milano - Bicocca. Via Cadore 48, I-20052 Monza, (MB), Italy. Electronic address: giancarlo.cesana@unimib.it.
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Cesana
mesh_terms: D002318:Cardiovascular Diseases / Q000628:therapy*; D006760:Hospitalization; D006801:Humans; D007297:Inpatients; D007558:Italy; D052638:Particulate Matter / Q000633:toxicity*; D010865:Pilot Projects; D012140:Respiratory Tract Diseases / Q000628:therapy*
chemical_list: D052638:Particulate Matter
keywords: Case-only analysis; Effect modification; Particulate matter; Pharmacological treatments