Differences in ambulatory versus home blood pressure levels by ethnicity: data from the United Kingdom and Japan

This study tested the hypothesis that differences in ethnicity impact the level of agreement between ambulatory blood pressure (ABP) and home BP (HBP) levels. A retrospective analysis of cross-sectional data from the UK and Japan was performed. Participants underwent office BP, daytime ABP, and HBP measurements. The ABP–HBP difference was compared between ethnic groups by multiple linear regression analysis. Diagnostic disagreement was defined as a disparity between the hypertension diagnoses obtained using ABP and HBP, since both measures share common thresholds of 135/85 mmHg for hypertension. Definite diagnostic disagreement was assigned where such a difference exceeded ±5 mmHg for either systolic BP (SBP) or diastolic BP (DBP). A total of 1 408 participants (age 62.1 ± 11.1 years, 48.6% males, 78.9% known hypertensive, White British 18.9%, South Asian 11.2%, African Caribbean 12.0%, Japanese 58.0%) were eligible. More Japanese participants showed higher ABP than HBP compared to White British: SBP + 3.09 mmHg, 95% confidence interval (CI) + 1.14, +5.04 mmHg; DBP + 5.67 mmHg, 95%CI + 4.51, +6.84 mmHg. More Japanese participants than African Caribbean participants exhibited diagnostic disagreement in SBP (33.2% vs. 20.7%, p = 0.006). Furthermore, Japanese participants had a higher percentage of definite diagnostic disagreement in SBP compared to White British (9.3% vs. 4.5%, p = 0.040) and African Caribbean participants (9.3% vs. 3.0%, p = 0.018). In conclusion, Japanese participants showed greater disparity between ABP and HBP compared to White British participants. Complementary use of ABP and HBP monitoring may be more beneficial for assessing cardiovascular disease risk in Japanese participants compared to other ethnic groups.