COPD Mortality in Colorado: The Role of Environmental Exposures, Regionality and Ethnicity

Chronic Obstructive Pulmonary Disease (COPD) is a condition caused by damage to the airways and alveoli that results in loss of elasticity, increased inflammation, increased mucus production and alveolar wall damage. This alveolar damage and mucus overproduction results in irreversible decreased airflow for those affected. While most COPD is attributable to past or current smoking, COPD can also result from environmental or occupational exposures. We examined COPD mortality data at the Zip Code Tabulation Area (ZCTA), the smallest geographic level available from the Colorado Department of Public Health and Environment, identifying spatial clustering and assessing the relationship between these clusters and markers of interest to public health. We found that spatial clustering of COPD mortality in Colorado is primarily explained by the population age and smoking status within the state. One cluster in the northern part of the state in the Greeley area was independent after adjusting for the age and smoking. This cluster has increased poverty, proximity to farming and ranching and a large Hispanic population. We then explored the role of Hispanic ethnicity and COPD mortality in a well characterized cohort in the San Luis Valley region of the state. We found a protective effect of Hispanic ethnicity on COPD mortality that was associated with smoking behavior. Hispanic participants reported a smaller number of pack years of smoking as non-Hispanic Whites. However this was achieved by accumulating more years of smoking with a lower number of cigarettes per day. Hispanics also reported less smoke inhalation compared to non-Hispanic whites. In summary, clustering of COPD mortality in the state of Colorado is associated with the age and smoking distribution across the state. Remaining clustering may be associated with Hispanic ethnicity, though in Hispanics living in the San Luis Valley ethnic differences in COPD mortality are explained by smoking behavior.