Reliability of Office, Home, and Ambulatory Blood Pressure Measurements and Correlation With Left Ventricular Mass

Abstract

Background: Determining the reliability and predictive validity of office blood pressure (OBP), ambulatory BP (ABP), and home BP (HBP) can inform which is best for diagnosing hypertension and estimating risk of cardiovascular disease.

Objectives: This study aimed to assess the reliability of OBP, HBP, and ABP and evaluate their associations with left ventricular mass index (LVMI) in untreated persons.

Methods: The Improving the Detection of Hypertension (IDH) study, a community-based observational study, enrolled 408 participants who had OBP assessed at 3 visits, and completed 3 weeks of HBP, 2 24-h ABP recordings, and a 2-dimensional echocardiogram. Mean age was 41.2 ± 13.1 years, 59.5% were women, 25.5% African American, and 64.0% Hispanic.

Results: The reliability of 1 week of HBP, 3 office visits with mercury sphygmomanometry, and 24-h ABP were 0.938, 0.894, and 0.846 for systolic and 0.918, 0.847, and 0.843 for diastolic BP, respectively. The correlations among OBP, HBP, and ABP, corrected for regression dilution bias, were 0.74 to 0.89. After multivariable adjustment including OBP and 24-h ABP, 10 mm Hg higher systolic and diastolic HBP were associated with 5.07 (standard error [SE]: 1.48) and 3.92 (SE: 2.14) g/m² higher LVMI, respectively. After adjustment for HBP, neither systolic or diastolic OBP nor ABP was associated with LVMI.

Conclusions: OBP, HBP, and ABP assess somewhat distinct parameters. Compared with OBP (3 visits) or 24-h ABP, systolic and diastolic HBP (1 week) were more reliable and more strongly associated with LVMI. These data suggest that 1 week of HBP monitoring may be the best approach for diagnosing hypertension.

Keywords: ambulatory blood pressure; home blood pressure; left ventricular mass index; office blood pressure; regression dilution bias; reliability.

Figure 1.. Design of the Improving the Detection of Hypertension study.

This shows the study visits and procedures completed by participants. Each participant had their blood pressure measured 9 times at office visits 1, 3 and 4 including three measurements using a mercury sphygmomanometer, the BpTRU automated oscillometric device and an Omron oscillometric device. Participants also completed three weeks of home blood pressure monitoring between visits 2 and 4 and 24-hour ambulatory blood pressure monitoring two times, between visits 1 and 2 and between visits 4 and 5. Actigraphy was assessed during both 24-hour ABPM recordings, primarily to accurately determine the start and end of each participant’s sleep period. During visit 5, participants had a cardiovascular evaluation which included a 2D echocardiogram. BP – blood pressure

Figure 2.. Correlations among office mercury, home and ambulatory systolic and diastolic blood pressure measurements, corrected for regression dilution bias, N=342.

Correlations among office mercury, home and 24-hour mean ambulatory systolic and diastolic blood pressure measurements, corrected for regression dilution bias, are shown as curved bi-directional arrows connecting pairs of blood pressures (green circles). For example, the correlation between participants’ systolic home blood pressure values and their mean awake ambulatory systolic blood pressure values is 0.89 after correction for regression dilution bias. Each green circle represents the “true” values of the specified type of blood pressure measurement; i.e., the latent (unobserved) variable that is being approximated by each repeat assessments of that blood pressure. The small black lines emanating from each green circle represent the multiple assessments and show the correlations of these observed blood pressure measures with the “true” values of that blood pressure. For example, the correlation of participants’ mean systolic home blood pressure for week 1 with their true systolic home blood pressure is 0.97. The squared value of this correlation (r²) equals the reliability of that specific measurement. The bottom portion of the figure shows the correlations among the three different methods of assessing office blood pressure, with each observed measurement (e.g., Visit 1) based on the average of 3 readings. BP – blood pressure, ABP – ambulatory blood pressure

Central Illustration.. Systolic Home BP is more reliable and more strongly correlated with left ventricular mass than either office BP or ambulatory BP.

Participants had their office BP (OBP) assessed at 3 visits (3 readings/visit) and completed 3 weeks of home BP monitoring (HBPM) and two 24-hour ambulatory BP monitoring (ABPM) recordings. We estimated the reliability (reproducibility) of mean BP of one week of HBPM, one 24-hour ambulatory BP recording ABPM and 3 office visits; the reliability of HBPM was greater than that of both 24-hr ABPM and OBP. We also estimated the correlation of each with left ventricular mass index (LVMI), with and without correction for regression dilution bias. HBPM was more highly correlated with LVMI than either 24-hr ABPM or OBP, both before (not shown) and after correction for regression dilution bias.