Ayanian JZ, Guadagnoli E, McNeil BJ, Cleary PD.
Treatment and outcomes of acute myocardial infarction among patients of cardiologist and generalist physicians.
Arch Intern Med 1997;157(22):2570-6.

The objective of this study was to determine whether patients with acute myocardial infarction (AMI) differed in terms of treatment received (drugs, procedures) and outcome (mortality) depending on whether they were seen by an attending generalist physician or a cardiologist.

Medicare beneficiaries of 65 to 79 years of age hospitalized in Texas with a diagnosis of acute myocardial infarction (AMI) from February 1990 to May 1990 were eligible for this study. Exclusion criteria were hospitalization for an AMI in the previous year, enrollment in an HMO, discharge within less than 5 days, or transfer to another hospital and change in principle diagnosis within two days. The final sample consisted of all eligible subjects who underwent angiography within 90 days of the initial hospitalization, as well as a random sample of those who did not have this procedure.

The data for this study were derived from the Medicare Provider Analysis and Review (MEDPAR) file of the Health Care Finance Administration and medical record reviews. Information on attending physicians was obtained following a detailed procedure, nurses abstracted treatment information based on a specified protocol, and data on rate of angiography, angioplasty, and bypass surgery were obtained from the MEDPAR files. Control variables in this analysis included age, sex, and clinical variables. The data were weighted to adjust for differing sampling probabilities of patients who did and did not receive angiography.

About one-third of the patients were treated by an attending cardiologist. Of the remaining patients, about half were evaluated by a consulting cardiologist. Patients who were treated by cardiologists (as opposed to those treated by generalists) were younger, male, and differed with regard to a range of clinical variables. Cardiologists were more likely to use thrombolytic therapy than generalists (32.9% versus 18.3%) and aspirin at discharge (66.3% versus 54.7%). Additionally, cardiologists were more likely to initiate thrombolytic therapy in the emergency department when it was used than generalists (51.6% versus 37.6%). Calcium channel blockers were also more frequently used by cardiologists, but there was no difference in the use of beta blockers. In general, when care was collaborative, rates for each practice fell midway between the rates for each of the two specialties. Each type of invasive procedure use was higher for cardiologists compared with generalists.

Mortality at the initial episode did not differ (14.9% for cardiologists versus 17.4% for generalists), but, after 30 days and after one year, mortality was lower among patients treated by an attending cardiologist. Adjustment for differences in hospital characteristics (hospitals with invasive procedure facilities versus not) eliminated the one-year mortality difference.

An in-depth evaluation of the role of institutions (especially process information) versus the role of physicians was not possible in this study, but institutional factors are likely to explain some of the variation in treatment and outcomes reported here.

Although no mention of race was made in this study, it is pertinent to understanding observed racial differences in cardiac care because some studies have shown that blacks with coronary heart disease are less likely than whites to see a cardiologist as opposed to a generalist.