National Health and Nutrition Examination Survey 1999-2000: Effect of observer training and protocol standardization on reducing blood pressure measurement error

Objective: We describe the National Health and Nutrition Examination Survey (NHANES) blood pressure (BP) observer training and protocol standardization and evaluate the quality of BP measurement. Methods: The participants were persons aged 8 years and older who had their BP measured (n = 7467) during NHANES 1999-2000. Cuff width/arm circumference ratio (CW/AC), end digit preference, and observer agreement were examined. Results: In stepwise principal components multiple regression analysis, CW/AC accounted for less than 2% of variability R-2 in all readings. The frequencies for all end digits were close to 20% ("0" end digit = 21% systolic and 23% diastolic). No overall observer effect was present for mean systolic BP readings. A significant observer effect (P <.0001) was detected for mean diastolic BP readings of <90 mm Hg. For readings of greater than or equal to90 mm Hg, there was no significant observer effect (P =.157). Conclusion: We conclude-that NHANES,BP measurements do not demonstrate the variability that is commonly caused by observer and technical error. (C) 2003 Elsevier Inc. All rights reserved.