Abstract 19277: Neither Comorbidities nor Socioeconomic Differences Explain the Association Between Higher Altitude of Residence and Better Coronary Artery Disease Survival

Abstract

Background: Previous studies have linked higher altitude of residence with lower mortality from coronary artery disease, but were limited by incomplete ascertainment of co-morbidities, including hypertension, dyslipidemia, diabetes, and smoking, as well as lack of adjustment for socioeconomic variables such as education status and household income.

Methods: We tested whether comorbidities and socioeconomic variables alter the association between altitude of residence and both results of coronary angiography and survival of those with coronary artery disease using the APPROACH database, a prospective cohort of all subjects undergoing coronary angiography in the Province of Alberta. Co-morbidities and mortality are ascertained by periodic linkage with Alberta Health, the provincial repository of administrative health data. The population was stratified by altitude of residence into quartiles based on residence postal codes, and logistic regression was used to calculate odds ratios for high risk or left main disease at coronary angiography, with the lowest quartile the reference. A Cox proportional hazard model was used to calculate hazard ratios for mortality, with the lowest quartile the reference.

Results: A total of 105,093 consecutive subjects referred for coronary angiography between 1995 and 2010 were included, spanning elevations between 210 meters to 2,164 meters. After adjustment for comorbidities and socioeconomic variables, the odds ratio for the highest quartile having high risk or left main coronary disease at angiography was 0.86 (0.82-0.90). Survival analysis was restricted to 78,349 subjects with at least one >50% coronary lesion. The hazard ratio for mortality for the highest quartile was 0.88 (0.84-0.93) adjusting for all variables except coronary anatomy, and 0.95 (0.90-0.99) after adjusting for all variables.

Conclusion: Higher altitude of residence was associated with lower odds of having high risk or left main coronary artery disease at coronary angiography and better survival, even after adjustment for comorbidities and socioeconomic variables.