Primary Prevention of CHD Risk Factors Occurring in US

BACKGROUND: The coronary heart disease risk factor profile of Americans has been improving, with decreasing blood pressure and cholesterol levels. However, it is not apparent whether this improvement is due to primary prevention of risk factors through lifestyle choices or to secondary prevention (management) of established risk factors. Since secondary prevention only targets people with high blood pressure or cholesterol levels, the effect should be demonstrated by temporal declines in the upper percentiles (75th, 90th) of the blood pressure and cholesterol distributions. Primary prevention should shift the entire risk factor distribution, including the percentiles in the middle (50th) and lower (10th, 25th) portions of the distribution. Thus, the effectiveness of primary prevention programs can be evaluated by examining temporal changes in the middle and lower percentiles, and the effectiveness of secondary prevention can be evaluated by examining temporal changes in the higher percentiles. DESIGN NARRATIVE: Data from the National Health Examination Survey and the National Health and Nutrition Examination Surveys were examined to determine whether more recent birth cohorts were attaining lower blood pressure and cholesterol levels than earlier birth cohorts. The results of these analyses provided information that may help guide further research and application of population prevention strategies. The study completion date listed in this record was obtained from the "End Date" entered in the Protocol Registration and Results System (PRS) record.