The National Center for Health Statistics (NCHS) is a principal agency of the U.S. Federal Statistical System which provides statistical information to guide actions and policies to improve the health of the American people. NCHS is housed within the Centers for Disease Control and Prevention (CDC), which is part of the United States Department of Health and Human Services (DHHS). The National Health and Nutrition Examination Survey (NHANES) is an NCHS survey, operating out of mobile examination centers that travel to randomly selected sites throughout the country to assess the health and nutritional status of Americans. The authority for NHANES derives from the 1956 National Health Survey Act, Public Law #652 of the 84th Congress, which authorized the DHHS Secretary to conduct a continuing survey of illness and disability in the Nation. As part of the charter for the program, funding for the surveys was to be obtained from other organizations within and external to the government. The NHLBI?s involvements focuses on the cardiovascular, pulmonary, and sleep health of US citizens, with cost-effective, highly reliable and valid measures. In June 2015, The NHLBI Council strongly recommended that NHANES replace the mercury devices currently in use for blood pressure measurement with suitable automatic oscillometric devices. The change will take place in NHANES for the 2019-2020 phase. The use of mercury in sphygmomanometers to measure blood pressure puts the environment at risk locally and globally due to the risk of mercury contamination associated with potential breakage. The NHLBI and NIH have been moving forward on a campaign to eliminate mercury sphygmomanometers from research clinics and to replace them with suitable replacements. Of paramount importance is the comparability of blood pressure data to monitor trends for the U.S. population, with the ultimate goal of assessing trends in hypertension prevalence and control. Mercury measurements have been the basis of estimates of trends in blood pressure going back more than 50 years. For mercury sphygmomanometers, rigorous training and testing for the certified operators, be they physician or technician, have been required. No device has been identified that can replicate the measurements from a mercury sphygmomanometer exactly. However, a suitable alternative device has been examined and has been found to provide measurements within 2% of those provided by mercury. Concerns about changes in proprietary algorithms and similar concerns will need to be addressed in the measurement protocol. In order to better address the issue of comparability of blood pressure measurements taken from oscillometric devices as compared to mercury devices, a calibration study will be performed to generate a calibration equation. The resulting calibration equation will be applied to oscillometric measurements to estimate trends. It is anticipated that the oscillometric measurements to be obtained will be comparable to measurement obtained earlier (1999-2018) using the heretofore standard mercury sphygmomanometer protocol. Documentation of the trends in key indicators of cardiovascular, lung, and sleep disorders are required to track the impact of national prevention and control programs. National data also are used to identify segments of the population not benefiting from risk reduction. NHANES is the only nationally-representative survey with both a questionnaire and clinical exam. Measurements for components are standardized and comparable across time to allow for trend analyses.
