Ambulatory blood pressure monitoring in daily practice

Establishment of a scoring model for the differential diagnosis of white coat hypertension and sustained hypertension

OBJECTIVES

This study aimed to establish a scoring model for the differential diagnosis of white coat hypertension (WCH) and sustained hypertension (SHT).

METHODS

This study comprised 553 adults with elevated office blood pressure, normal renal function, and no antihypertensive medications. Through questionnaire investigation and biochemical detection, 17 parameters, such as gender and age, were acquired. WCH and SHT were distinguished by 24 h ambulatory blood pressure monitoring. The participants were randomly divided into a training set (445 cases) and a validation set (108 cases). The above parameters were screened using least absolute shrinkage and selection operator regression and univariate logistic regression analysis in the training set. Afterward, a scoring model was constructed through multivariate logistic regression analysis.

RESULTS

Finally, six parameters were selected, including isolated systolic hypertension, office systolic blood pressure, office diastolic blood pressure, triglyceride, serum creatinine, and cardiovascular and cerebrovascular diseases. Multivariate logistic regression was used to establish a scoring model. The R2 and area under the ROC curve (AUC) of the scoring model in the training set were 0.163 and 0.705, respectively. In the validation set, the R2 of the scoring model was 0.206, and AUC was 0.718. The calibration test results revealed that the scoring model had good stability in both the training and validation sets (mean square error = 0.001, mean absolute error = 0.014; mean square error = 0.001, mean absolute error = 0.025).

CONCLUSION

A stable scoring model for distinguishing WCH was established, which can assist clinicians in identifying WCH at the first diagnosis.

Ambient temperature and ambulatory blood pressure: An hourly-level, longitudinal panel study

BACKGROUND

Variations of blood pressure (BP) related to air temperature have been reported previously; however, no evidence is available regarding the association of hourly ambient temperature with ambulatory blood pressure.

METHODS

We conducted a longitudinal panel study among 1895 patients from an outpatient department who received repeated ambulatory blood pressure monitoring in Urumqi, China between July 2020 and December 2021. We obtained hourly ambient temperature from the nearest monitoring station to the residential address, and measured 4 ambulatory blood pressure indicators. Linear mixed-effect model combined with distributed lag models were applied to investigate the cumulative associations of hourly temperature with BP.

RESULTS

A total of 97,466 valid blood pressure measurements were evaluated. We observed almost linear and monotonically decreasing relationships between temperature and blood pressure. The effects occurred in the same hour, attenuated thereafter and became insignificant approximately 36 h. A 10 °C decrease in temperature was significantly associated with increments of 0.84 mmHg in systolic blood pressure, 0.56 mmHg in diastolic blood pressure, 1.38 mmHg in mean arterial pressure, and 0.66 mmHg in pulse pressure over lag 0 to 36 h. Stronger associations were found among patients of female sex, age between 18 and 65 years, overweight or obesity, minority, less education or in the cold season, as well as those without hypertension or with coronary heart disease, or did not take anti-hypertension medication.

CONCLUSION

Our study provides robust evidence that hourly ambient temperature is inversely associated with ambulatory blood pressure. It also highlights a linear relationship between decreased ambient temperature and elevated BP, which may have implications for the prevention and management of hypertension in susceptible populations.

Relations between white coat effect of blood pressure and arterial stiffness

The aim of this study was to analyze the relationship between brachial-ankle pulse wave velocity (b-a PWV) and white coat effect (WCE), that is the difference between the elevated office blood pressure (BP) and the lower mean daytime pressure of ambulatory BP, in a mixed population of normotention, untreated sustained hypertension, sustained controlled hypertension, sustained uncontrolled hypertension, white coat hypertension, white coat uncontrolled hypertension. A total of 444 patients with WCE for systolic BP (54.1% female, age 61.86 ± 13.3 years) were enrolled in the study. Patients were separated into low WCE (<9.5 mm Hg) and high WCE (≥9.5 mm Hg) according to the median of WCE. The subjects with a high WCE showed a greater degree of arterial stiffness than those with a low WCE for systolic BP values (P < .05). The b-a PWV were 17.2 ± 3.3 m/s and 18.4 ± 3.4 m/s in low WCE and high WCE, respectively. The b-a PWV increased with the increase of WCE, showing a positive correlation between them (P > .05 for non-linearity). The significant association between the high WCE and the b-a PWV was confirmed by the results of multiple regression analysis after adjusting for confounding factors (β = .78, 95% Cl .25-1.31, P = . 004). Similar results were observed in subgroups. In conclusion, WCE is significantly associated with arterial stiffness. More research is needed to determine the WCE and target organ damage.

The acute effects of particulate matter air pollution on ambulatory blood pressure: A multicenter analysis at the hourly level

Epidemiological evidence from ambulatory blood pressure monitoring is needed to clarify the associations of particulate air pollution with blood pressure and potential lag patterns. We examined the associations of fine and coarse particulate matter (PM_2.5, PM_2.5-10) with ambulatory blood pressure among 7108 non-hypertensive participants from 7 Chinese cities between April 2016 and November 2020. Hourly concentrations of PM_2.5 and PM_2.5-10 were obtained from the nearest monitoring stations. We measured four blood pressure indicators, including systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP) and pulse pressure (PP). Linear mixed-effect models combined with distributed lag models were applied to analyze the data. Generally, very short-term exposure to PM_2.5 was significantly associated with elevated blood pressure. These effects occurred on the same hour of blood pressure measurement, attenuated gradually, and became insignificant approximately at lag 12 h. An interquartile range (IQR, 33 μg/m³) increase of PM_2.5 was significantly associated with cumulative increments of 0.58 mmHg for SBP, 0.31 mmHg for DBP, 0.38 mmHg for MAP, and 0.33 mmHg for PP over lag 0 to 12 h. The exposure-response relationship curves were almost linear without thresholds, but tended to be flat at very high concentrations. No significant associations were observed for PM_2.5-10. Our study provides independent and robust associations between transient PM_2.5 exposure and elevated blood pressure within the first 12 h, and reinforces the evidence for a linear and non-threshold exposure-response relationship, which may have implications for blood pressure management and hypertension prevention in susceptible population.

Ambulatory Blood Pressure Monitoring: Our Experience in Routine Clinical Practice

Objective: To evaluate feasibility and usefulness of ambulatory blood pressure monitoring (ABPM) in outpatient setting.

Material and methods: In this prospective study, data of 58 patients who were evaluated with ABPM for diagnosis or therapeutic efficacy purpose were collected from their records. Demographic details of these were recorded. Patients were categorized into different categories based on 24 hours BP pattern. Dipping pattern was compared based on the gender, age, and presence of diabetes or hypertension. Number of patients diagnosed as hypertensive with ABPM reports was compared with office and home BP measurement.

Results: Fifty-eight patients (mean age 57.8 years; 70.69% males) were included of whom 22 (37.93%) underwent ABPM for diagnostic purposes. There was gender-wise significant difference in terms of purpose of performing ABPM (p=0.040). Diabetes was present in 22 (37.93%) patients. Out of 36 known hypertensive patients, 17 (47.22%) patients were receiving dual therapy. Out of 45 patients whose records for active BP variability were available, 26 (57.78%) had high variability. The number and percentage of dippers, extreme dippers and reverse dippers as 23 (42.79%), three (5.56%), and six (11.11%), respectively. Depending on the age, there was significant difference in the dipping pattern (p=0.013). On office blood pressure measurement, 35 (64.81%) patients were found to have hypertension. ABPM revealed hypertension in 32 (59.26%). Masked hypertension and white-coat hypertension was observed in nine (16.17%) and 12 (22.22%) patients, respectively.

Conclusion: ABPM is feasible and useful in routine outpatient clinical practice for diagnosis of essential hypertension, pattern of dipping, masked hypertension, and white-coat hypertension and also for the therapeutic evaluation of patients in clinical practice.

Pathogenesis of Higher Blood Pressure and Worse Renal Function in Salt-Sensitive Hypertension

BACKGROUND

The underlying pathogenesis of patients with salt-sensitive hypertension expressing higher blood pressure and severer renal damage remains uncertain.

METHODS

We recruited 329 subjects, 131 in salt-sensitive (SS) group, 148 in nonsalt-sensitive (NSS) group, and 50 healthy people in normal group and tested their renal function, 24-h ambulatory blood pressure, and growth factor series.

RESULTS

The SS group showed worse renal function with lower estimated glomerular filtration rate and higher urinary microalbumin, α-microglobulin, urinary protein Cr ratio, and urinary immunoglobulin. Most indicators in 24-h ambulatory blood pressure of the SS group were significantly enhanced than the NSS group, indicating their higher blood pressure. The significantly elevated growth factors in the SS group were AR, BMP-5, EG-VEGF, GH, HGF, IGFBP-2, IGFBP-3, IGFBP-6, MCSFR, NT-4, PDGF-AA, SCF, SCFR, VEGFR2, VEGFR3, and VEGF-D, compared to other 2 groups or one of them. PI3K-AKT pathway was activated in the SS group.

CONCLUSIONS

Differences in growth factors and pathways may account for the manifestations of the SS group. Activated PI3K-AKT pathway with higher IGFBP-3 and GH can lead to renal damage. Higher MCSFR in the SS group indicates that high blood pressure and severe kidney damage may be associated with the activation of the immune system. EG-VEGF, VEGFR2, VEGFR3, and VEGF-D can also explain the elevated blood pressure due to the dilated lymphatic system which drains excess sodium and water back into circulation. The SS group presented higher AR and HGF which may worsen renal function by regulating cell proliferation and tumor formation. However, due to the potential low awareness rate of hypertension at the very beginning, we cannot ensure the exact occurrence order of blood pressure, renal damage, and salt sensitivity. Therefore, further studies which can track data from the onset of hypertension are needed.

Diagnostic Comparability and Interchangeability Between Daytime Ambulatory Blood Pressure Monitoring and 24-Hour Ambulatory Blood Pressure Monitoring in Detecting Masked Hypertension

Background The primary aim of this study was to evaluate the level of diagnostic overlap between daytime ambulatory blood pressure (BP) monitoring (DT-ABPM) and 24-hour ambulatory BP monitoring (24-h ABPM) in detecting masked hypertension (MH). Methods This is a prospective study that was performed in a sample of 196 soldiers aged between 21 and 50 years (without a history of hypertension) undergoing ABPM testing. The diagnosis of MH based on DT-ABPM defined as (office blood pressure (OBP) <140/90 and DT-ABPM ≥135/85) was compared with the 24-h ABPM defined as (OBP <140/90 mm Hg and 24-h ABPM ≥130/80 mm Hg). We critically analyzed the results to see the agreement between the two methods. Results The number of subjects classified as having MH based on both DT-ABPM and 24-h ABPM, only on 24-h ABPM, and only on DT-ABPM were 11 (5.6%), 29 (14.8%), and 18 (9.2%), respectively. The sensitivity, specificity, and positive and negative predictive values for DT-ABPM in detecting MH were: sensitivity = 100% (95% CI: 97.82% - 100%), specificity = 62.07% (95% CI: 42.26% - 79.31%), PPV = 93.82% (95% CI: 90.50% - 96.03%), and NPV = 100%, respectively. The level of agreement between DT-ABPM and 24-h ABPM in diagnosing MH was 94.4% and discordance in 5.6% (11/196); (kappa=0.736, p < 0.001). Conclusion The sensitivity, specificity, positive and negative predictive values all showed agreement between the two BP methods to confirm the diagnoses of MH. DT-ABPM can be used as an alternative to the 24-h ABPM. DT-ABPM eliminates sleep disturbance attributable to ABPM and maximizes patient compliance with the ABPM test. A further larger trial is needed for more confirmation and to affect the guidelines for using daytime ABPM.

Effects of walnut intake on blood pressure: A systematic review and meta-analysis of randomized controlled trials

The impact of walnuts on blood pressure (BP) is not a well-established fact. Although several studies have assessed the effects of walnut consumption on BP, results are conflicting. Thus, we examined the effects of walnut doses and length of supplementation on BP. Biomedical databases were searched for published trials that compared walnut-enhanced diet to control diet. Eighteen trials met eligibility criteria (n = 1,799). Overall, walnut consumption neither did alter SBP (weighted mean difference [WMD]: 0.08 mmHg; 95% CI: -0.69, 0.85) nor DBP (WMD: 0.08 CI: -0.26, 0.42). In subgroup analyses, walnut ingestion ≤40 g was statistically correlated with reduction in SBP (WMD: -0.53 mmHg, 95% CI: -0.79, -0.26) and DBP (WMD: -0.191 mmHg, 95% CI: -0.384, -0.034). Moreover, the length of intervention ≥8 weeks was linked to a significant reduction in SBP (WMD: -1.18 mmHg, 95% CI: -1.30, -1.06). Following dose-response evaluation, walnut intake significantly changed SBP (p = .015) and DBP (p = .026) through a nonlinear fashion at walnut dose up to 40 g/d. Nevertheless, these statistical results cannot be translated into clinical practice, once the changes expressed as WMD are slight taking into consideration the absolute values of BP categories. In conclusion, this meta-analysis does not support walnut consumption as a BP-lowering strategy.

Ambulatory blood pressure monitoring in clinical practice

Being one of the most widely prevalent diseases throughout the world, hypertension has emerged as one of the leading causes of global premature morbidity and mortality. Hence, blood pressure (BP) measurements are essential for physicians in the diagnosis and management of hypertension. Current American College of Cardiology/American Heart Association (ACC/AHA) guidelines recommend initiating antihypertensive medications on the basis of office BP readings. However, office BP readings provide a snapshot evaluation of the patient's BP, which might not reflect patient's true BP, with the possibility of being falsely elevated or falsely low. Recently, there is ample evidence to show that ambulatory blood pressure monitoring (ABPM) is a better predictor of major cardiovascular events than BP measurements at clinic settings. ABPM helps in reducing the number of possible false readings, along with the added benefit of understanding the dynamic variability of BP. This article will focus on the significance of ambulatory BP, its advantages and limitations compared with the standard office BP measurement and a brief outlook on its use and interpretation to diagnose and treat hypertension.