Rhonda Spencer-Hwang, Synnove Fonnebo Knutsen, Mark Ghamsary, W. Lawrence Beeson, Keiji Oda, David Shavlik, Navin Jaipaul and Sam Soret
Background: There is increasing evidence that specific ambient air pollutants are associated with coronary heart disease (CHD) morbidity and mortality and risks may differ by gender. Renal transplant recipients have previously been identified as a potentially sensitive subgroup. The purpose of this study was to evaluate the possible effect of long-term ambient pollutant ozone (O3) and particulate matter (PM10) on risk of coronary heart disease (CHD) mortality and determine if gender differences exist among renal transplant recipients.
Methods: This retrospective cohort study included 38,101 (22,276 males and 15,825 females) subjects identified through the US Renal Data System (USRDS), which included adult, renal transplant recipients, transplanted between 1997-2003, and living in the continental U.S.A. Air pollution statistics collected over the national ambient monitoring network, were extracted from US Environmental Protection Agency (EPA) Air Quality System (AQS). Mean monthly concentrations of O3, and PM10 calculated from ambient monitoring data and interpolated to ZIP code centroids according to residence of the subjects. Cox proportional hazard models used to estimate effect of air pollutants on mortality (CHD) risks, while adjusting for potential confounders. All analyses conducted were gender-specific.
Results: In both the age-and multivariable adjusted models, there was a significant association between risk of fatal CHD and O3 for females (HR=1.56, 95%CI: 1.06-2.30), no significant association found for males. O3 displayed the strongest association with CHD mortality among females with a HR=1.57 (95%CI: 1.07-2.30) after adjustment for PM10 in the two pollutant multivariable model. For both pollutants and across all models, females consistently experienced greater risk than males. No significant association identified for PM10 for either gender.
Conclusions: The findings from our study have potential implications for policies and regulations of air pollution. Gender, as a higher risk category, may be relevant in developing individual CHD risk reduction strategies for renal transplant recipients to ultimately improve long-term survival.