Lambert A. Wu

Number needed to treat: Caveat emptor

Number needed to treat (NNT)-the inverse of the absolute risk reduction resulting from an intervention-was introduced as a yardstick to describe the harm as well as the benefit of therapeutic maneuvers. Analysis using NNT works well when comparing two or more interventions that have their impact over the same period of time in similar populations or patients. Under other conditions, however, analysis based on NNT can produce results that diverge widely from the impact that the interventions can be expected to have on risk of death. This can happen either for entire populations or for an individual when comparing NNTs for interventions which have their effects on different subsets of the population or when comparing interventions which have their effects over different periods of time. We demonstrate how this can occur by comparing the NNTs and effect of intervention on deaths in a population for automatic implantable cardioverter defibrillators (AICDs), heart transplantation, and cholesterol lowering through nutritional intervention with plant stanol ester.

Current Role of Endomyocardial Biopsy in the Management of Dilated Cardiomyopathy and Myocarditis

Dilated cardiomyopathy is a common cause of congestive heart failure. Despite a thorough cardiovascular evaluation, a specific cause is frequently not found, and the disorder then is considered idiopathic. Endomyocardial biopsy (EMB) may yield diagnostic and prognostic information in patients with idiopathic dilated cardiomyopathy; however, the yield of useful information with this procedure among patients with heart failure is low, and the risks of occasional cardiac perforation and death further limit its use. Recent publications in the field of myocarditis and cardiomyopathy have renewed interest in the use of EMB in select patients to diagnose specific and potentially treatable myocarditides; however, the role of EMB in the work-up of patients with dilated cardiomyopathy is not well defined. In this article, we discuss the risks and utility of EMB in the management of patients with dilated cardiomyopathy and specific myocarditides.

Economic and Psychological Implications of the Obesity Epidemic

The medical literature, lay press, and evening news all tell us that an unprecedented number of US adults and children are becoming obese. More than half of adults and more than 20% of children report that they are overweight or obese, 1,2 and the number of obese adults increased by 61% between 1991 and 2000. 1 In our community, Olmsted County, Minnesota, we found that the self-reported prevalence of overweight and obese individuals is 47.9% and 17.7%, respectively, among men and 30.7% and 17.2%, respectively, among women. 3 The problem is even worse than these figures indicate. Measured rates of obesity are more than 50% higher than rates based on self-report. Physical examination data from the National Health and Nutrition Examination Survey indicate that age-adjusted prevalence of obesity increased from 22.9% in 1988 through 1994 to 30.5% in 1999 through 2000. 4

The Eosinophil in Cardiac Disease

Eosinophils were first described by Wharton-Jones’ as coarse granule cells in 1846. It was not until Ehrlich’s2 1879–1880 paper that these cells became known as “eosinophils.” The association between eosinophils and clinical diseases has been known for many years, but only recently, through more detailed analyses, has their role in the pathogenesis of disease been elucidated.

Implantable cardioverter defibrillator implantation rates in the Olmsted County, Minnesota, population: 1989-1999.

Although the efficacy of implantable cardioverter defibrillators (ICDs) has been demonstrated in randomized clinical trials, implantation and survival rates have not been reported for a defined population. We performed a retrospective cohort analysis of Olmsted County, Minnesota residents (n = 70) who received their first ICD between 1 January 1989 and 31 December 1999. The ICD implantation rate increased from approximately 2.5/100,000 (95% confidence interval [CI], 0.9-4.1) in the first 4 years to 11.5/100,000 (95% CI, 6.7-16.2) in the last 2 years. Twenty-three patients (33%) received an appropriate ICD shock during the observation period. Based on these data, ICDs are estimated to reduce total mortality rates in this population by 0.3%. We conclude that, in patients drawn from a community setting with AHA/ACC class I indications for ICD implantation, implantation of ICDs appears to be highly efficacious in aborting potentially fatal events.

Opportunities to prevent sudden out-of-hospital death due to coronary heart disease in a community

BACKGROUND Intervening successfully to reduce the burden of sudden out-of-hospital death due to coronary heart disease (OHCD) requires knowledge of where these deaths occur and whether they are observed by bystanders. METHODS To establish the proportion of OHCDs that were witnessed and where they occurred, we reviewed the coroners notes and medical records of a previously-described sample of OHCD cases among residents of Olmsted County, Minnesota. This cohort (n=113) consisted of a 10% random sample of all Olmsted County residents who died out-of-hospital between 1981 and 1994 and whose deaths were attributed to coronary heart disease. RESULTS Excluding deaths in nursing homes (n=27), 71 (83%) of the deaths occurred in private homes and 15 (17%) occurred in public places. The event was not witnessed in 59% of deaths occurring in private homes and in 20% of deaths occurring in public places. The presence or absence of a bystander could not be established for 10% of deaths in private homes and 7% of deaths in public areas. CONCLUSIONS A significant proportion of OHCDs occur in private homes and are not witnessed. Prevention of unwitnessed deaths will require programs that result in primary prevention and/or calls to first responders at the time of impending cardiac arrest.

Design and development of a coronary heart disease decision support tool

We are developing a decision support tool to help clinicians and policy makers estimate the impact of various coronary heart disease (CHD) treatments on disease outcomes for populations. We have created seven modules that correspond to states commonly encountered with CHD, that is, congestive heart failure, tachyarrhythmia, stable angina pectoris, acute coronary syndrome, bradycardia, postmyocardial infarction, and postcoronary artery bypass grafting, and a healthy individual module. Within each module, we created event-decision- intervention-outcome flow pathways to simulate risk of a clinical event and the expected outcome as the result of a particular intervention. We will combine disease state probability estimates based on the experience of the Olmsted County, Minnesota, population and estimates of intervention efficacy based on clinical trial data to estimate the impact of interventions on a population. We plan to make this tool available to the public through the internet.

The Potential Impact of CardioVision 2020 and Three Other Risk Factor Scenarios on Population Rates of Coronary Heart and Cardiovascular Disease: A Call to Action

Background: We are implementing CardioVision 2020—a comprehensive, population-wide initiative—in Olmsted County, Minnesota to reduce the population burden of coronary heart disease (CHD) and cardiovascular (CVD) disease. In this analysis we compare disease incidence rates expected with CardioVision 2020 to three other scenarios.