Reliability and reproducibility of clinic and home blood pressure measurements in hypertensive women according to age and ethnicity.

BACKGROUND: The purposes of this study were to establish the reproducibility and reliability of clinic and home blood pressure readings and to determine whether correlations differed according to age and ethnicity. METHODS: Blood pressure readings taken in a clinical setting and at home from 161 hypertensive women who were either younger or older (including 91 White American and 61 African-American) were compared with 24-h ambulatory blood pressure monitoring (ABPM) readings (considered the gold standard of blood pressure measurement). RESULTS: Bland-Altman statistical method showed good levels of agreement between clinic blood pressures measured 30 days apart, and blood pressures measured at home in the morning over a 30-day program, when compared with mean 24-h ABPM readings. On examining individual Bland-Altman plots for younger and older women, White American and African-American women's blood pressures were well correlated for home measures and 24-h ABPM readings. The correlation between daytime systolic home blood pressure readings and systolic 24-h ABPM readings was much stronger for White American women (r=0.75) than for African-American women (r=0.57). There were also correlation differences in mean systolic blood pressure between home blood pressure readings and 24-h ABPM readings according to age (r=0.66 for younger and r=0.72 for older). CONCLUSION: These results support current research findings that home blood pressure measurements are reliable when compared with 24-h ABPM readings both in African-American and White women.