Accuracy of home versus ambulatory blood pressure monitoring in the diagnosis of white-coat and masked hypertension.

BACKGROUND: We investigated accuracy of home blood pressure (BP) monitoring in the diagnosis of white-coat and masked hypertension in comparison with ambulatory BP monitoring. METHODS: Our study participants were enrolled in the China Ambulatory and Home BP Registry, and underwent clinic, home, and 24-h ambulatory BP measurements. We defined white-coat hypertension as an elevated clinic SBP/DBP (≥140/90 mmHg) and a normal 24-h ambulatory (<130/80 mmHg) or home SBP/DBP (<135/85 mmHg), and masked hypertension as a normal clinic SBP/DBP (<140/90 mmHg) and an elevated 24-h ambulatory (≥130/80 mmHg) or home SBP/DBP (≥135/85 mmHg). RESULTS: In untreated patients (n = 573), the prevalence of white-coat hypertension (13.1 vs. 19.9%), masked hypertension (17.8 vs. 13.1%), and sustained hypertension (46.4 vs. 39.6%) significantly (P ≤ 0.02) differed between 24-h ambulatory and home BP monitoring. In treated patients (n = 1201), only the prevalence of masked hypertension differed significantly (18.7 vs. 14.5%; P = 0.005). Regardless of the treatment status, home compared with 24-h ambulatory BP had low sensitivity (range 47-74%), but high specificity (86-94%), and accordingly low positive (41-87%), but high negative predictive values (80-94%), and had moderate diagnostic agreement (82-85%) and Kappa statistic (0.41-0.66). In untreated and treated patients, age advancing was associated with a higher prevalence of white-coat hypertension and a lower prevalence of masked hypertension defined by 24-h ambulatory (P ≤ 0.03) but not home BP (P ≥ 0.10). CONCLUSION: Home BP monitoring has high specificity, but low sensitivity in the diagnosis of white-coat and masked hypertension, and may therefore behave as a complementary to, but not a replacement of, ambulatory BP monitoring.

System for simultaneous measurements of bilaterally symmetrical acupoints multifrequency impedances.

Devices which can obtain comparable bilaterally symmetrical acupoints (BSA) multifrequency impedances (MFI) are often needed in the detection of the energy balance states of acupoints in traditional Chinese medicine. To satisfy these needs, a two-channel impedance measurement system has been introduced which is capable of accurately and simultaneously measuring BSA MFI. The system includes a set of five electrodes, two of which are injected with exciting current signal to synchronously and equally excite BSA; the other three electrodes are used as sensors to simultaneously sense the response signal from both sides. The system also includes a PC-based time-domain signal testing platform with arbitrary current waveform generation and three channels (one exciting current and two response voltages) simultaneously sampling, and a set of MFI simultaneously unbiased computing algorithms based on special odd multisine current signal input. Preliminary validating experiments suggest that the system allows accurate and synchronous measurement of BSA MFI at least in the frequency range of 10 Hz to 60 kHz, and the obtained BSA MFI are well comparable.