Geographic variations in percutaneous coronary interventions and coronary artery bypass graft surgery among Tennessee elders

Abstract

Objectives: Coronary heart disease often presents with ST segment elevation acute myocardial infarction (STEMI). The American College of Cardiology/American Heart Association guidelines stress prompt reperfusion for STEMI. Examining geographic variations in treatment with PPCI (percutaneous primary coronary intervention) and CABG (coronary artery bypass graft) among metropolitan, micropolitan and non-micropolitan rural residents provides a descriptive basis for generating hypotheses concerning place and receipt of guidelines-based treatment.

Methods: Using ICD-9 codes for STEMI and excluding beneficiaries with pre-existing MI in claims data, yielded a subset of 18,775 Tennessee Medicare beneficiaries experiencing STEMI from 1996 to 2002. The outcome variable is type of treatment, i.e., in accord (PPCI or CABG present) or not in accord (PPCI or CABG absent) with guidelines. Independent variables include type county residence, hospital volume, race, gender, and age. Analyses include cross-tabulation and logistic regression, estimating separate models by age and type of MI.

Results: Micropolitan residents with STEMI have the lowest rates for PPCI (18.8%) versus 28.1% percent for metropolitan and 24.2% for non-micropolitan rural residents. CABG follows similar patterns at lower overall rates. Treatment at a heart center with high volume PPCI mediated the relationship between the likelihood of PPCI and place.

Conclusion: The correspondence between metropolitan and rural utilization suggests that access to a full range of treatment options and likelihood of "best practice" care is not dependent on metropolitan residence. This presents the possibility that with some policy changes, e.g., centralization of emergency heart care, the same may ultimately be true for micropolitan residents.