BLOOD-PRESSURE MEASUREMENT IN CHILDHOOD EPIDEMIOLOGIC STUDIES

Background Accurate measurement of blood pressure in childhood epidemi ological studies requires standardized conditions, valid instruments, and multiple measurements. Methods and Results We used published liter ature and our own data to make recommendations on the reduction of bia ses caused by various technical factors, to discuss the advantages and disadvantages of selected measurement devices, and to evaluate the op timal number of visits and measurements per visit for accurate estimat ion of a child's blood pressure level. The conditions under which bloo d pressure is measured should be standardized. This includes training and certification to minimize observer biases; equipment factors such as use of an appropriate cuff bladder size, subject factors such as mi nimizing activities before and during the reading, environmental facto rs such as accounting for the time of day and ambient temperature, and technique factors such as recording both the fourth and fifth Korotko ff sounds. The choice of instrument for measuring blood pressure depen ds on the goals of the study and the resources available to the invest igators. Conclusions Although relatively economical and easy to use, t he standard mercury sphygmomanometer is subject to the bias resulting from knowledge of earlier readings. The random-zero sphygmomanometer o vercomes this bias, but it is more expensive and difficult to use and may underestimate blood pressure levels. In contrast to auscultatory d evices, automated oscillometric devices are not subject to observer bi ases. They are gaining wider use and may be especially appropriate for younger children. However, they are expensive, and each model require s validation before use in epidemiological studies. Ambulatory blood p ressure monitoring represents a potentially useful technique for futur e epidemiological studies. Multiple measurements are vital in estimati ng a child's blood pressure, and the number of visits, days or weeks a part, is at least as important as the number of measurements per visit .