BLOOD-PRESSURE MEASUREMENTS IN EPIDEMIOLOGIC SURVEYS - TIME TO CHANGE

Blood pressure recordings in epidemiological surveys are usually obtai ned by non-ambulatory, multiple one-occasion, manual sphygmomanometric measurements by trained observers in study participants subjected to standardized examination conditions. High validity and reliability of blood pressure measurements ensure the comparability of study results obtained in different places and at different times, and have a major impact on the detection of correlates and determinants of blood pressu re and hypertension. A blood pressure measurement quality assessment w as performed within the multi-center collaborative WHO-MONICA Project investigating results of 47 surveys from various geographic regions of the world. In an overall summary assessment, six out of these 47 surv eys were found to have had major measurement problems which prohibited their further inclusion in collaborative analyses. Most of the proble ms were associated with observer-related factors. Therefore, it was co ntended that automatic blood pressure measurement devices might be abl e to reduce and abolish most of these ''nuisance'' factors. In 1995, w e had the opportunity to simultaneously study two independent random s amples of men and women, aged 45 to 64 years, from the city of Augsbur g in Southern Germany. One sample was examined by 16 observers with a random zero sphygmomanometer (MONICA Augsburg), the other sample (J.A. P. Study) was examined by two observers with an invasively validated, automatic oscillometric device (bose Oscillomat). In both surveys, blo od pressure was measured three times under similarly standardized cond itions. Comparing the blood pressure results of the two surveys, the i ntra-individual measurement variation tended to be slightly higher wit h the Oscillomat than with the random zero, and the population mean bl ood pressures and hypertension prevalences were found to be significan tly lower with the Oscillomat. We conclude that manual measurements of blood pressure by sphygmomanometer should not be indiscriminately rep laced by externally validated automatic devices. The imponderabilities of automatic devices with varying technical principles have to be ass essed in epidemiological settings and weighed against recognized disad vantages of sphygmomanometry before any recommendations can be given a s to changing the present epidemiological practice.