Cost-effectiveness of prevention referrals for high-risk HIV-negatives in San Francisco.

We retrospectively assessed the cost-effectiveness of providing prevention referrals to high-risk seronegatives at HIV test sites in San Francisco. We examined the costs and effects from the perspectives of society and the San Francisco Department of Public Health (SFDPH). Cost categories assessed included referral materials, counsellor training and time required to make referrals, prevention services and the value of client time. Effect data are drawn from a study of 289 high-risk seronegatives and the published literature, and are applied to a city-wide caseload of 6,626 high-risk seronegatives. We estimate that a city-wide programme in San Francisco averts two HIV infections per year and yields net savings to society of $43,765, with a cost to the SFDPH of $20,738 per HIV infection averted. We conclude that providing HIV prevention referrals to high-risk seronegatives receiving antibody testing imposes significant costs, but has attractive cost-effectiveness when applied to a large high-risk population.

The use of vasopressin in the treatment of upper gastrointestinal haemorrhage.

Vasopressin is a potent vasoconstrictor which greatly reduces mesenteric blood flow. In patients with portal hypertension this results in decreased portal venous flow and portal pressure. Because of this property, vasopressin has been used for years in the therapy of variceal haemorrhage. A few controlled trials show that vasopressin causes a decrease in bleeding but has no effect on survival. It has been shown that intravenous vasopressin is just as effective as intra-arterial, and is associated with fewer complications. The inability to influence the outcome of variceal haemorrhage significantly may be related to suboptimal dosing due to the occurrence of systemic complications at higher doses. The combination of vasopressin with either sodium nitroprusside or nitroglycerin (glyceryl trinitrate) has resulted in a further decline of portal pressure, along with amelioration of most of the adverse haemodynamic effects of vasopressin. Whether or not clinical efficacy is increased when vasopressin is combined with sodium nitroprusside or nitroglycerin remains to be proven. Analogues of vasopressin, such as terlipressin, held early promise as agents which would be as effective as vasopressin, without the cardiac adverse effects. Recent data have not supported this and at present there is little to suggest any advantage of terlipressin over vasopressin. Virtually no adequate studies have yet been performed to support the use of vasopressin in the treatment of non-variceal haemorrhages. There is reason to suspect that vasopressin can effectively control bleeding from haemorrhagic gastritis, but the subsequent results of inducing gastric ischaemia in an already damaged gastric mucosa are unknown. In summary, vasopressin appears to have little effect on the mortality of patients with variceal haemorrhage. It may, however, help control the haemorrhage in some patients by lowering the portal pressure. Cardiovascular complications limit the dose that can be used but it is hoped that by combining vasopressin with nitroglycerin, a more effective and safe therapy will be available for variceal haemorrhages.

Physicians' estimates of the probability of myocardial infarction in emergency room patients with chest pain.

To evaluate the ability of emergency room physicians to estimate the probability of myocardial infarction in patients with acute chest pain, the authors gathered historical, physical, and electrocardiographic information from 492 patients at the time of their presentation. The physicians admitted 30% of them to intensive care: 53 of the 61 patients with infarctions (sensitivity = 87%) and 96 of the 431 without infarctions (specificity = 78%). Overall, 36% of those admitted had infarctions. The physicians' numeric estimate of the probability of infarction was a good univariate discriminator of infarction, as demonstrated by Receiver Operator Characteristics analysis, and, as indicated by their actual operating point, they seemed to maximize the accuracy of patient classification rather than sensitivity or specificity. Logistic regression analysis identified the physicians' probability estimate as the strongest multivariate predictor of infarction, considering all other clinical information available.

Predictors of myocardial infarction in emergency room patients.

To develop a decision rule to aid in the diagnosis of myocardial infarction, we evaluated clinical and ECG data on 540 adults treated in an urban hospital emergency room for acute chest pain. Of 62 (11.5%) patients who had acute infarctions, 54 were admitted to intensive care (sensitivity 87%); 103 of 478 patients without infarctions were also admitted to intensive care (specificity 78%). Thirty-four percent of all patients admitted had infarctions. Multivariate analysis identified only four clinical variables which carried independent information predicting infarction: two from the ECG and two from the clinical history. A predictive model based on these four variables had significantly greater specificity (86% vs. 78%, p = .003) and accuracy of overall patient classification (88% vs. 79%, p = .013) but somewhat lower sensitivity (81% vs. 87%, p = .46) than physician judgments. However, a decision rule which would have admitted to intensive care those patients with a high probability of infarction who were not admitted by the emergency room physicians, would have increased the sensitivity for detecting infarction to 95% with no appreciable decrease in specificity or yield of infarctions among patients admitted to intensive care.