Under-estimation of obesity, hypertension and high cholesterol by self-reported data: comparison of self-reported information and objective measures from health examination surveys

Background: Non-communicable diseases (NCDs) cause 63% of deaths worldwide. The leading NCD risk factor is raised blood pressure, contributing to 13% of deaths. A large proportion of NCDs are preventable by modifying risk factor levels. Effective prevention programmes and health policy decisions need to be evidence based. Currently, self-reported information in general populations or data from patients receiving healthcare provides the best available information on the prevalence of obesity, hypertension, diabetes, etc. in most countries. Methods: In the European Health Examination Survey Pilot Project, 12 countries conducted a pilot survey among the working-age population. Information was collected using standardized questionnaires, physical measurement and blood sampling protocols. This allowed comparison of self-reported and measured data on prevalence of overweight, obesity, hypertension, high blood cholesterol and diabetes. Results: Self-reported data under-estimated population means and prevalence for health indicators assessed. The self-reported data provided prevalence of obesity four percentage points lower for both men and women. For hypertension, the self-reported prevalence was 10 percentage points lower, only in men. For elevated total cholesterol, the difference was 50 percentage point among men and 44 percentage points among women. For diabetes, again only in men, the self-reported prevalence was 1 percentage point lower than measured. With self-reported data only, almost 70% of population at risk of elevated total cholesterol is missed compared with data from objective measurements. Conclusions: Health indicators based on measurements in the general population include undiagnosed cases, therefore providing more accurate surveillance data than reliance on self-reported or healthcare-based information only.