The cardiovascular tolerance for sex has largely been equated with physical activity, yet sexual arousal plays a major role. Exercise testing is useful, primarily for evaluating functional capacity, which reflects the extent of physical conditioning and the limitation imposed by symptoms of angina, dyspnea, and fatigue. Exercise testing, which is useful for evaluating functional capacity in sedentary patients, is generally unnecessary in physically active patients. Exercise testing, with or without radionuclide imaging, is of limited value in assessing the risk of future cardiovascular events-a limitation shared by all diagnostic tests, including coronary angiography. The absolute risks of coition-induced myocardial infarction (MI) or death are extremely low-on the order of 2 chances per million per hour in healthy middle-aged individuals or 20 chances per million per hour in "high-risk" patients with ischemic heart disease. This is equivalent to an annual risk of 1. 01% and 1.2%, respectively. Sex is a comparatively weak precipitant of acute coronary events, accounting for only 0.5-1.0% of all such events. The cardiovascular tolerance for sex in an individual can be characterized by the "functional reserve," that is, the extent to which the cardiovascular response to sex-measured by the heart rate, blood pressure, and oxygen consumption-encroaches on the peak response to exercise. Cardiovascular symptoms during sex rarely occur in patients who do not experience similar symptoms during exercise testing at a level equivalent to 6 METS.

Sexual dysfunction is highly prevalent in both sexes and adversely affects patients' quality of life and well being. Given the frequent association between sexual dysfunction and cardiovascular disease, in addition to the potential cardiac risk of sexual activity itself, a consensus panel was convened to develop recommendations for clinical management of sexual dysfunction in patients with cardiovascular disease. Based upon a review of the research and presentations by invited experts, a classification system was developed for stratification of patients into high, low, and intermediate categories of cardiac risk. The large majority of patients are in the low-risk category, which includes patients with (1) controlled hypertension; (2) mild, stable angina; (3) successful coronary revascularization; (4) a history of uncomplicated myocardial infarction (MI); (5) mild valvular disease; and (6) no symptoms and 3 cardiovascular risk factors. These patients can be safely encouraged to initiate or resume sexual activity or to receive treatment for sexual dysfunction. An important exception is the use of sildenafil in patients taking nitrates in any form. Patients in the intermediate-risk category include those with (1) moderate angina; (2) a recent MI (6 weeks); (3) left ventricular dysfunction and/or class II congestive heart failure; (4) nonsustained low-risk arrhythmias; and (5) >/=3 risk factors for coronary artery disease. These patients should receive further cardiologic evaluation before restratification into the low- or high-risk category. Finally, patients in the high-risk category include those with (1) unstable or refractory angina; (2) uncontrolled hypertension; (3) congestive heart failure (class III or IV); (4) very recent MI (2 weeks); (5) high-risk arrhythmias; (6) obstructive cardiomyopathies; and (7) moderate-to-severe valvular disease. These patients should be stabilized by specific treatment for their cardiac condition before resuming sexual activity or being treated for sexual dysfunction. A simple algorithm is provided for guiding physicians in the management of sexual dysfunction in patients with varying degrees of cardiac risk.

Selected by the editors of Contemporary Pediatrics as the most significant pediatric study of 1999. Also first printed in 1999, v 282, p1561-1567 JAMA

OBJECTIVES: This study determined the cost-effectiveness of expanding methadone maintenance treatment for heroin addiction, particularly its effect on the HIV epidemic.

METHODS: We developed a dynamic epidemic model to study the effects of increased methadone maintenance capacity on health care costs and survival, measured as quality-adjusted life-years (QALYs). We considered communities with HIV prevalence among injection drug users of 5% and 40%.

RESULTS: Additional methadone maintenance capacity costs $8200 per QALY gained in the high-prevalence community and $10,900 per QALY gained in the low-prevalence community. More than half of the benefits are gained by individuals who do not inject drugs. Even if the benefits realized by treated and untreated injection drug users are ignored, methadone maintenance expansion costs between $14,100 and $15,200 per QALY gained. Additional capacity remains cost-effective even if it is twice as expensive and half as effective as current methadone maintenance slots.

CONCLUSIONS: Expansion of methadone maintenance is cost-effective on the basis of commonly accepted criteria for medical interventions. Barriers to methadone maintenance deny injection drug users access to a cost-effective intervention that generates significant health benefits for the general population.

The 35 chapters of The Handbook of Health Economics provide an up-to-date survey of the burgeoning literature in health economics. As a relatively recent subdiscipline of economics, health economics has been remarkably successful. It has made or stimulated numerous contributions to various areas of the main discipline: the theory of human capital; the economics of insurance; principal-agent theory; asymmetric information; econometrics; the theory of incomplete markets; and the foundations of welfare economics, among others. Perhaps it has had an even greater effect outside the field of economics, introducing terms such as opportunity cost, elasticity, the margin, and the production function into medical parlance. Indeed, health economists are likely to be as heavily cited in the clinical as in the economics literature. Partly because of the large share of public resources that health care commands in almost every developed country, health policy is often a contentious and visible issue; elections have sometimes turned on issues of health policy. Showing the versatility of economic theory, health economics and health economists have usually been part of policy debates, despite the vast differences in medical care institutions across countries. The publication of the first Handbook of Health Economics marks another step in the evolution of health economics.

Also prepared for the 3rd Annual NBER Frontiers in Health Policy Research conference, Washington, DC, June 17, 1999.

This paper describes the ATHENA Decision Support System (DSS), which operationalizes guidelines for hypertension using the EON architecture. ATHENA DSS encourages blood pressure control and recommends guideline-concordant choice of drug therapy in relation to comorbid diseases. ATHENA DSS has an easily modifiable knowledge base that specifies eligibility criteria, risk stratification, blood pressure targets, relevant comorbid diseases, guideline-recommended drug classes for patients with comorbid disease, preferred drugs within each drug class, and clinical messages. Because evidence for best management of hypertension evolves continually, ATHENA DSS is designed to allow clinical experts to customize the knowledge base to incorporate new evidence or to reflect local interpretations of guideline ambiguities. Together with its database mediator Athenaeum, ATHENA DSS has physical and logical data independence from the legacy Computerized Patient Record System (CPRS) supplying the patient data, so it can be integrated into a variety of electronic medical record systems.