Assessing blood pressure accuracy of an aneroid sphygmomanometer in a national survey environment.

BACKGROUND The "gold standard" employed for obtaining blood pressure (BP) for all the National Health and Nutrition Examination Surveys (NHANES) has been the mercury sphygmomanometer (HgS). Because of environmental concerns, there is a need to explore an alternative to HgS. METHODS We compared the accuracy of the Welch Allyn 767 wall aneroid sphygmomanometer (AnS) to the HgS in children and adults and by BP cuff sizes. Each participant had three BP measurements per device recorded sequentially. The order of the devices and observer were random. A total of 727 individuals participating in the NHANES participated in the study. RESULTS The mean AnS readings were not statistically significantly different from those of the HgS with the exception of systolic BP (SBP) in aged 8-17 years (mean difference 1.10, s.d. 4.87). There were no statistically significantly different by BP cuff sizes. Agreement for the prevalence of hypertension (BP ≥140 systolic or diastolic ≥90 mm Hg) was above chance (κ = 0. 81; sensitivity = 81%; specificity = 98%) with AnS readings underestimating by 1.66% (18.33 vs. 20%, P > 0.05) compared to the HgS reading. CONCLUSIONS With the exception of SBP in ages 8-17 years, the AnS device readings were not significantly different from HgS readings by age or BP cuff sizes selection. Agreement for hypertension classification is good. An accurate and well-calibrated AnS could therefore provide an acceptable alternative to the use of a HgS in surveys, although with appropriate caution given the 81% sensitivity with regard to hypertension thresholds that was observed.