Date of Award

10-20-2006

Document Type

Open Access Thesis

Degree Name

Medical Doctor (MD)

First Advisor

Barbara Gulanski

Abstract

Diabetics have higher mortality after myocardial infarction (MI), yet little is known regarding the impact of quality of care on long-term survival in older post-MI diabetics. Using data from the Cooperative Cardiovascular Project (CCP), a national cohort of 234,769 Medicare patients aged 65 or older hospitalized with confirmed AMI between 1994-1995, we assessed differences in 10-year mortality outcomes between diabetics and non-diabetics using Cox proportional regression. To account for quality of care, a composite measure among ideal candidates was constructed and entered into the final model adjusting for use of aspirin & beta-blocker on admission/discharge, angiotensin-converting enzyme inhibitors at discharge, reperfusion within 6 hours of admission, and smoking counseling at discharge. We also assessed the relationship between insulin use, sulfonylureas/biguanides, and statin therapy and long-term mortality within the diabetic cohort. The final study sample included 203,658 cases: 32% were diabetics. Compared to non-diabetics, diabetics were younger (75 vs. 76, p<0.001), female (53% vs. 47%, p<0.001), had more comorbidities, and unlikely to receive evidence-based care (59% vs. 64%, p<0.001). The unadjusted HR for mortality among diabetics vs. non-diabetics was 1.38 (95% CI: 1.37-1.40). After adjusting for demographics, past medical history, procedures during hospitalization, medications on admission/discharge, and quality of care, the HR was 1.29 (95% CI: 1.27-1.31). Among diabetics, those on insulin or oral hypoglycemic therapy during the initial hospitalization for AMI had the highest risk of mortality during the last 7 years, after adjustment for demographics, clinical characteristics, and quality of care (HR insulin=1.30, 95% CI: 1.25-1.35; HR oral hypoglycemics=1.11, 95% CI: 1.08-1.15) whereas those on statin therapy were not at increased risk (HR statin=0.95, 95% CI: 0.90-1.02). As compared to non-diabetics, older diabetics had a 29% increase in mortality even after adjusting for demographics, clinical variables during hospitalization, and quality of care (HR=1.29, 95% CI: 1.27-1.31). Additionally, within the diabetic cohort, the risk of long-term mortality was highest among those on insulin or oral hypoglycemic therapy during initial hospitalization for AMI. Our study demonstrates that neither patient characteristics nor quality of care fully account for the poor outcomes among diabetics suggesting that metabolic risk factors associated with diabetes ultimately require therapies beyond those currently recommended for post-MI patients.

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This is an Open Access Thesis.

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