Analysis of the MRFIT screenees: a methodological study

Review Article: Learning and knowledge-production for public health: a review of approaches to evidence-based public health

Public health needs to be evidence-based if it is to be done correctly, which means that learning and knowledge-production for public health must be comprehensive and include knowledge from four different domains: distribution of health, determinants or causal web, consequences, and intervention methods. Specification of development trends in cardiovascular prevention points at four generations of preventive programs; these include a clinical, a bioepidemiological, a socioepidemiological, and an environmental and policy-oriented generation. Generations differ in focus and strategy, in knowledge base - the art of making an impact - and evaluation. Comprehensive public health programs often comprise components from different generations, leading to the need for an expanded model for research and evaluation. There is an urgent need for learning and knowledge-production using both quantitative and qualitative approaches for developing the evidence base for public health action. In addition, epidemiological knowledge is necessary for making appropriate priorities.

Considerations on guidelines of epidemiologic practice

Epidemiologists in the United States have been intrigued for almost two decades by the prospect of guidelines of epidemiologic practice: an issue partially raised by a perceived need for criteria that may distinguish advocacy positions from more conservative interpretations in epidemiology. Preliminary efforts have considered questions of subject protection, of study structure and documentation, and of professional etiquette. Deeper ethical interests have been coalescing around the need for candor and truth in the interpretation of uncertain epidemiologic findings--a need construed to be central to trustworthiness, and whose consideration would bring about a reappraisal of other aspects of epidemiologic practice. Openness about uncertainties would likely develop naturally into a search for ways to measure the relative strength of epidemiologic warnings, as an aid to ranking public health priorities. Principles aimed at resolving ethical, operational, and priority questions become interdependent elements of professional guidelines for epidemiology.

The Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT): clinical center recruitment experience

The Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) is a randomized clinical outcome trial of antihypertensive and lipid-lowering therapy in a diverse population (including substantial numbers of women and minorities) of 42,419 high-risk hypertensives aged > or = 55 years with a planned mean follow-up of 6 years. In this paper, we describe our experience in the identification, recruitment, and selection of clinical centers for this large simple trial capable of meeting the recruitment goals outlined for ALLHAT, and we highlight factors associated with clinical center performance. Over 135,000 recruitment brochures were mailed to physicians. Requests for information and application packets were received from 9351 (6.8%) interested investigators. A total of 1053 completed applications were received and 909 sites (86%) were eventually approved to join the trial. Of the approved sites, 278 either later declined participation or were never activated, and 8 were closed within a year for lack of enrollment. The final 623 randomizing centers exceeded the trial's recruitment goal to enroll at least 40,000 participants into the trial, although the recruitment period was extended 1.5 years longer than planned. Fewer than a quarter of the sites (22.6%) were recruited from academic medical centers or Department of Veterans Affairs Medical Centers. More than half of the sites (54.7%) were private solo or group practices, which contributed 53% of randomized participants. Community health centers comprised about 8% of the ALLHAT sites and 2.9% were part of health maintenance organizations. More than 22% of the principal investigators reported that they had no previous clinical research experience. In summary, ALLHAT was successful in recruiting a diverse group of clinical centers to achieve its patient recruitment goals.

Coronary heart disease, hypercholesterolemia, and atherosclerosis. II. Misrepresented data

Early development of the hypercholesterolemic/lipid hypothesis of atherosclerosis was based on false premises including fallacious national mortality rates and misrepresentation of the vascular lesions in cholesterol-overfed animals and monogenic hypercholesterolemias (MH). Nonspecific coronary heart disease (CHD) was inappropriately used as a surrogate of atherosclerosis, unmeasured and unseen. Causality was assumed and implied by classifying statistical correlates of CHD as atherogenic risk factors. These faults were compounded by methodological errors, pooling of all causes of CHD, a large clinical diagnostic error, biased age selection of cohorts leading to confounding by age and MH, and emphasis on population and cohort mean values which conceal heterogeneity within cohorts and are inapplicable to individuals. Overzealous investigators neglected to review the premises and relevant pathology on which the hypothesis was based or to reconcile valid criticisms, inconsistencies, and invalidation of CHD epidemiology by pathological, experimental, and iatrogenic evidence. Statistical data, pertaining to CHD but with no scientific applicability to atherosclerosis, progressively imparted to readers a misleading perception of the relationship of serum cholesterol to CHD. Concurrently the statistical serum cholesterol range was unjustifiably abandoned. The evidence establishes that the lipid hypothesis of atherosclerosis lacks scientific basis.