ATHENA DSS is a decision-support system that provides recommendations for managing hypertension in primary care. ATHENA DSS is built on a component-based architecture called EON. User acceptance of a system like this one depends partly on how well the system explains its reasoning and justifies its conclusions. We addressed this issue by adapting WOZ, a declarative explanation framework, to build an explanation function for ATHENA DSS. ATHENA DSS is built based on a component-based architecture called EON. The explanation function obtains its information by tapping into EON's components, as well as into other relevant sources such as the guideline document and medical literature. It uses an argument model to identify the pieces of information that constitute an explanation, and employs a set of visual clients to display that explanation. By incorporating varied information sources, by mirroring naturally occurring medical arguments and by utilizing graphic visualizations, ATHENA DSS's explanation function generates rich, evidence-based explanations.

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.

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.

First published in Pharmacoeconomics, Volume 14, pages 27-48, 1998.

We present a methodology and database mediator tool for integrating modern knowledge-based systems, such as the Stanford EON architecture for automated guideline-based decision-support, with legacy databases, such as the Veterans Health Information Systems & Technology Architecture (VISTA) systems, which are used nation-wide. Specifically, we discuss designs for database integration in ATHENA, a system for hypertension care based on EON, at the VA Palo Alto Health Care System. We describe a new database mediator that affords the EON system both physical and logical data independence from the legacy VA database. We found that to achieve our design goals, the mediator requires two separate mapping levels and must itself involve a knowledge-based component.