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J Clin Epidemiol. 2003 Aug;56(8):768-74.

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

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Division of Health Examination Statistics, National Center for Health Statistics, NHANES Program, 3311 Toledo Road, Room 4319, Centers for Disease Control and Prevention, Hyattsville, MD 20782, USA.



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.


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.


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 > or =90 mm Hg, there was no significant observer effect (P=.157).


We conclude that NHANES BP measurements do not demonstrate the variability that is commonly caused by observer and technical error.

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