Doctors should average blood pressure measured by different methods to classify BP control
TUESDAY, June 21 (HealthDay News) -- An average of several blood pressure (BP) measurements should be used to classify patients' BP control, as a single clinic recording is not a meaningful quality metric, according to a study published online June 20 in the Annals of Internal Medicine.
Benjamin J. Powers, M.D., M.H.S., from the Durham Veterans Affairs Medical Center in North Carolina, and colleagues investigated the accuracy of various strategies used to measure BP at home or in clinics for 444 veterans with hypertension, and the effect of these strategies on classifying patients as having BP that was in or out of control. Strategies used were standardized research BP measurements at six-month intervals, electronic BP monitor at home, and BP recording at outpatient clinic visits. Participants were followed up for 18 months, during which time they provided 111,181 systolic BP (SBP) measurements.
The investigators found a substantial variation in the SBP control rates at baseline with similarly large short-term variability for all methods. The mean within-patient coefficient of variation was 10 percent, which was greatly reduced by averaging several measurements, with maximum benefit achieved by averaging five to six measurements. SBP was classified as controlled in 28, 47, and 68 percent of clinic, home, and research measurements, respectively. A single clinic SBP measurement was insufficient to classify patients with 80 percent certainty as having BP that was controlled or uncontrolled.
"Physicians who want to have 80 percent or more certainty that they are correctly classifying patients' BP control should use the average of several measurements," the authors write.
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