Specialist physicians, by virtue of their narrower focus, can more readily keep up with changes in clinical knowledge as they occur. This appears to be especially true for cardiac care, where changes in treatment paradigms occur frequently. Cardiologists also have the advantage of seeing a larger number of patients with heart conditions, so they have more experience with the range of variation in presenting symptoms and responses to therapy. Numerous studies comparing the performance of cardiologists and primary care physicians, or generalists, in providing patient care tend to support the view that cardiologists provide a higher level of cardiac care. For example, researchers have found that cardiologists demonstrate a better understanding of the appropriate use and relative efficacy of alternative treatments for heart attacks and congestive heart failure than generalists. Moreover, cardiologists are generally quicker to put successful innovations into practice and to discontinue using therapies shown to be less effective. This has been found in the treatment of unstable angina as well as heart attacks. Studies have also demonstrated that cardiologists are more likely to follow well-established treatment guidelines than generalists. Several studies report that cardiologists are more likely to prescribe cholesterol-lowering drugs to patients with elevated cholesterol levels and beta-blockers to heart attack survivors. A smaller group of studies has found that cardiologists achieve better outcomes—including for inpatient care for heart attacks. Similar differences in practice patterns between specialists and generalists have been found in the treatment of noncardiac conditions as well, such as ulcers and strokes. The findings of these studies do not mean that cardiologists always provide superior care. First, each study reports an overall tendency, with considerable variation in performance among both cardiologists and noncardiologists. Moreover, some noncardiologists do better than others. For example, in several studies, the performance of internists comes closer to that of cardiologists (cardiology is actually a subspecialty within internal medicine) than family practitioners. Nonetheless, within cardiac care, studies reveal a fairly consistent pattern—as physician specialization increases, so does the overall level of adherence to established standards of care. These studies, however, generally do not address the extent to which HMOs affect the pattern of care provided by cardiologists compared with that provided by noncardiologists. The handful of studies looking at physician specialty differences within an HMO setting have focused on other medical conditions. Specifically, we found two recent studies by researchers employed by HMOs that compared the treatment of asthma sufferers cared for by primary care physicians and allergy and asthma specialists.Statistically adjusting for disease severity and patient characteristics, both studies found that patients of specialists received more thorough and appropriate care. Specialists’ patients more often reported taking medications recommended by national treatment guidelines, had improved day-to-day functioning, and had fewer asthma exacerbations requiring emergency room treatment. These findings suggest that treatment differences across specialties can persist within an HMO structure. However, in cardiac care, comparable differences in care provided by primary care providers and cardiologists might not be found if, for example, HMOs placed a higher priority on standardizing care for cardiac patients. Our study compares the use of three specific pharmacological treatments among Medicare heart attack survivors who saw cardiologists regularly and those who did not. Although use of these drugs represents only a portion of the post-heart-attack care available, we chose to focus our analysis on this subset of treatments because (1) there is strong scientific evidence that these treatments are beneficial for a large proportion of heart attack survivors and (2) other data indicate that many patients who would benefit from these drugs are not using them. These two conditions do not apply to nearly the same extent to other aspects of care provided to heart attack survivors. For example, while there is considerable variation in the extent to which invasive procedures—such as cardiac catheterizations, angioplasty, and coronary artery bypass graft surgery—are performed on heart attack survivors, the evidence for these procedures is not as definitive as the evidence supporting the use of cholesterol-lowering drugs, beta-blockers, and aspirin. As a result, existing clinical guidelines for their use rest primarily on expert judgment. For many cases, that judgment is either equivocal or divided. Thus, it is more difficult to determine whether any given group of patients is getting either too many or too few of these procedures. The value of cholesterol-lowering drugs, beta-blockers, and aspirin for heart attack survivors has been widely publicized through practice guidelines as well as numerous articles in prominent medical journals. It is therefore reasonable to expect physicians to know about these therapies and to provide them to most of their patients, while recognizing that the general benefits of these drugs may not apply to certain individual patients. Since we limited the scope of our study to these drugs, we cannot assume that our findings are indicative of relative performance in other aspects of care, such as the appropriate use of invasive procedures. However, restricting the scope of this study to a set of well-defined and well-supported therapies means that we can identify with greater certainty a substantial number of patients who stood to benefit from the treatments in question. Multiple, large-scale randomized clinical trials support the widespread use of three pharmacological treatments in caring for heart attack survivors. Cholesterol-lowering medications: A series of large-scale clinical trials have demonstrated the substantial therapeutic benefit of using “statin” drugs (HMG CoA reductase inhibitors) and other medications (in addition to proper diet and exercise) to lower the cholesterol level of people with coronary heart disease—including those who have had a heart attack. These studies show a reduction in subsequent coronary-related deaths for heart attack survivors ranging from 20 percent (for those with normal cholesterol levels) to 42 percent (for those with high cholesterol). These studies have also shown a reduction in strokes of about 30 percent for both normal- and high-cholesterol patients. These trials have been published in prominent journals and extensively described in the national media. In 1993, the National Heart, Lung, and Blood Institute (NHLBI) issued practice guidelines that spelled out the implications of these trials for follow-up care of heart attack survivors. Whether a patient should get such therapy depends on his or her baseline level of low-density lipoprotein (LDL) cholesterol. The guidelines set an LDL goal for coronary heart disease patients of 100 mg/dL, well below the average level for the population as a whole. Those with baseline LDL levels of 130 mg/dL and above are definite candidates for cholesterol-lowering medications, although specific factors in individual cases can provide countervailing reasons not to initiate drug therapy. For those with baseline readings between 129 and 101, the guidelines recommend that physicians carefully weigh the expected benefits and risks of cholesterol-lowering therapy for each patient. Beta-Blockers: A second drug therapy whose benefits for heart attack survivors are well established in the clinical literature involves long-term use of beta-blockers. This class of drugs inhibits stimulation of the heart and reduces the force of heart muscle contractions, thereby decreasing both the workload placed on the heart and arrhythmias that can lead to sudden death. Beginning in the early 1980s, a series of large-scale clinical trials demonstrated that beta-blockers reduced overall mortality among heart attack survivors by about 25 percent. Subsequent studies provided additional confirmation of these effects. Another study found that among the elderly patients surveyed, those receiving beta-blockers were 43-percent less likely than nonrecipients to die in the 2 years following their heart attacks. In August 1990, the American College of Cardiology (ACC) and the American Heart Association (AHA) jointly issued guidelines on the management of heart attacks that cited these studies in support of a general recommendation to treat heart attack survivors with beta-blockers for at least 2 years, with the exception of patients who had specific contraindications. Six years later, ACC and AHA issued revised guidelines that repeated this recommendation, while reducing somewhat the scope of the stipulated contraindications. In the years since the first beta-blocker trials were published, the proportion of heart attack patients considered eligible to use them has expanded. In particular, the therapeutic value of beta-blockers for many patients with moderately severe heart failure has become more evident over time. Thus, current ACC and AHA practice guidelines list only relative contraindications, meaning that in each case, the specific risks posed by beta-blockers for these patients should be weighed against the general benefits. Aspirin: The 1990 practice guidelines for treating heart attacks issued by ACC recommended long-term aspirin therapy for all post-heart-attack patients “who could tolerate it.” In its 1996 revised guidelines, ACC specified that daily aspirin therapy should be continued indefinitely, with substitution of other antiplatelet agents only in the case of a “true aspirin allergy.” As with cholesterol-lowering medications and beta-blockers, multiple randomized clinical trials provided the basis for these recommendations. A pooled analysis of these trials indicated that long-term aspirin therapy led to a 13-percent reduction in vascular mortality, a 31-percent reduction in recurrent nonfatal heart attacks, and a 42-percent reduction in nonfatal strokes. The measure of appropriate care used in this study is whether patients reported that they were actually taking cholesterol-lowering drugs, beta-blockers, and aspirin about 2 years after their heart attack occurred—not if these drugs were prescribed. While tallying prescriptions would be a more direct measure of one aspect of physician behavior, none of the potential benefits of the drugs are realized unless the patient is actually taking them. Moreover, research has demonstrated that self-reported drug use is strongly related to more proximate measures of medication compliance, such as pharmacy records of prescriptions filled and counts of pills taken. While it is ultimately the patient who decides how faithfully to adhere to a treatment regimen, research has shown that physicians strongly influence patient behavior by, among other actions, prescribing certain medications, closely monitoring patient compliance, and by simplifying and adjusting regimens to encourage compliance.