Long-term outcomes of regional variations in intensity of invasive vs. medical management of Medicare patients with acute myocardial infarction

Context — The health and policy implications of the marked regional variations in intensity of invasive compared with medical management of patients with acute myocardial infarction (AMI) are unknown.

Objectives — To evaluate patient clinical characteristics associated with receiving more intensive treatment; and to assess whether AMI patients residing in regions with more intensive invasive treatment and management strategies have better long-term survival than those residing in regions with more intensive medical management strategies.

Design, Setting, and Patients — National cohort study of 158,831 elderly Medicare patients hospitalized with first episode of confirmed AMI in 1994-1995, followed up for 7 years (mean, 3.6 years), according to the intensity of invasive management (performance of cardiac catheterization within 30 days) and medical management (prescription of beta-blockers to appropriate patients at discharge) in their region of residence. Baseline chart reviews were drawn from the Cooperative Cardiovascular Project and linked to Medicare health administrative data.

Main Outcome Measure — Long-term survival over 7 years of follow-up.

Results — Patient baseline AMI severity was similar across regions. In all regions, younger and healthier patients were more likely than older high-risk patients to receive invasive treatment and medical therapy. Regions with more invasive treatment practice styles had more cardiac catheterization laboratory capacity; patients in these regions were more likely to receive interventional treatment, regardless of age, clinical indication, or risk profile. The absolute unadjusted difference in 7-year survival between regions providing the highest rates of both invasive and medical management strategies and those providing the lowest rates of both was 6.2%. For both ST- and non-ST-segment elevation AMI patients, survival improved with regional intensity of both invasive and medical management. In areas with higher rates of medical management, there appeared to be little or no improvement in survival associated with increased invasive treatment.

Conclusions — In elderly Medicare patients with AMI, more intensive medical treatment provides population survival benefits. However, routine use of more costly and invasive treatment strategies may not be associated with an overall population benefit beyond that seen with excellent medical management. Efforts should focus on directing invasive clinical resources to patients with the greatest expected benefit.