Interarm Difference in Systolic Blood Pressure in Different Ethnic Groups and Relationship to the "White Coat Effect": A Cross-Sectional Study

Cutoffs for white-coat and masked blood pressure effects: an ambulatory blood pressure monitoring study

The values used to define white-coat and masked blood pressure (BP) effects are usually arbitrary. This study aimed at investigating the accuracy of various cutoffs based on the differences (ΔBP) between office BP (OBP) and 24h-ambulatory BP monitoring (ABPM) to identify white-coat (WCH) and masked (MH) hypertension, which are phenotypes coupled with adverse prognosis. This cross-sectional study included 11,350 [Derivation cohort; 45% men, mean age = 55.1 ± 14.1 years, OBP = 132.1 ± 17.6/83.9 ± 12.5 mmHg, 24 h-ABPM = 121.6 ± 11.4/76.1 ± 9.6 mmHg, 25% using antihypertensive medications (AH)] and 7220 (Validation cohort; 46% men, mean age = 58.6 ± 15.1 years, OBP = 136.8 ± 18.7/87.6 ± 13.0 mmHg, 24 h-ABPM = 125.5 ± 12.6/77.7 ± 10.3 mmHg; 32% using AH) unique individuals who underwent 24 h-ABPM. We compared the sensitivity, specificity, positive and negative predictive values and area under the curve (AUC) of diverse ΔBP cutoffs to detect WCH (ΔsystolicBP/ΔdiastolicBP = 28/17, 20/15, 20/10, 16/11, 15/9, 14/9 mmHg and ΔsystolicBP = 13 and 10 mmHg) and MH (ΔsystolicBP/ΔdiastolicBP = -14/-9, -5/-2, -3/-1, -1/-1, 0/0, 2/2 mmHg and ΔsystolicBP = -5 and -3mmHg). The 20/15 mmHg cutoff showed the best AUC (0.804, 95%CI = 0.794-0.814) to detect WCH, while the 2/2 mmHg cutoff showed the highest AUC (0.741, 95%CI = 0.728-0.754) to detect MH in the Derivation cohort. Both cutoffs also had the best accuracy to detect WCH (0.767, 95%CI = 0.754-0.780) and MH (0.767, 95%CI = 0.750-0.784) in the Validation cohort. In secondary analyses, these cutoffs had the best accuracy to detect individuals with higher and lower office-than-ABPM grades in both cohorts. In conclusion, the 20/15 and 2/2 mmHg ΔBP cutoffs had the best accuracy to detect hypertensive patients with WCH and MH, respectively, and can serve as indicators of marked white-coat and masked BP effects derived from 24 h-ABPM.

Prevalence of interarm blood pressure difference is notably higher in women; the Viborg population-based screening program (VISP)

BACKGROUND

Bilateral blood pressure (BP) measurement is important in cardiovascular prevention for identifying systolic interarm BP difference (IAD) and hypertension. We investigated sex-stratified IAD prevalence and its associations and coexistence with screen-detected peripheral atherosclerosis and hypertension. Furthermore, we determined the proportion misclassified as non-hypertensive when using the lower versus the higher reading arm.

METHODS

This sub-study formed part of the Viborg Screening Program (VISP), a cross-sectorial population-based cardiovascular screening programme targeting 67-year-old Danes. VISP includes screening for peripheral atherosclerosis (lower extremity arterial disease and carotid plaque), abdominal aortic aneurysm, hypertension, diabetes mellitus, and cardiac disease. Self-reported comorbidities, risk factors, and medication use were also collected. Among 4,602 attendees, 4,517 (82.1%) had eligible bilateral and repeated BP measurements. IAD was defined as a systolic BP difference ≥ 10 mmHg. IAD-associated factors (screening results and risk factors) were estimated by logistic regression; proportional coexistence was displayed by Venn diagrams (screening results).

RESULTS

We included 2,220 women (49.2%) and 2,297 men (50.8%). IAD was more predominant in women (26.8%) than men (21.0%) (p < 0.001). This disparity persisted after adjustment [odds ratio (OR) 1.53; 95% confidence interval (CI) 1.32-1.77]. No other association was recorded with the conditions screened for, barring potential hypertension: BP 140-159/90-99 mmHg (OR 1.68, 95% CI 1.44-1.97) and BP ≥ 160/100 mmHg (OR 1.82, 95% CI 1.49-2.23). Overall, IAD and BP ≥ 160/100 mmHg coexistence was 4% in women and 5% in men; for BP ≥ 140/90 mmHg, 13% and 14%, respectively. Among those recording a mean BP ≥ 140/90 mmHg in the higher reading arm, 14.5% of women and 15.3% of men would be misclassified as non-hypertensive compared with the lowest reading arm.

CONCLUSION

Female sex was an independent factor of IAD prevalence but not associated with other arterial lesions. Approximately 15% needed reclassification according to BP ≥ 140/90 mmHg when the lower rather than the higher reading arm was used; verifying bilateral BP measurements improved detection of potential hypertension. In future, the predictive value of sex-stratified IAD should be assessed for cardiovascular events and death to verify its potential as a screening tool in population-based cardiovascular screening.

TRIAL REGISTRATION FOR VISP

NCT03395509:10/12/2018.

Clinical relevance of double-arm blood pressure measurement and prevalence of clinically important inter-arm blood pressure differences in Indian primary care

Hypertension guidelines recommend measuring blood pressure (BP) in both arms at least once. However, this is seldom done due to uncertainties regarding measurement procedure and the implications of finding a clinically important inter-arm BP difference (IAD). This study aimed to provide insight into the prevalence of clinically important IADs in a large Indian primary care cohort. A number of 134 678 (37% female) unselected Indian primary care participants, mean age 45.2 (SD 11.9) years, had BP measured in both arms using a standardized, triplicate, automated simultaneous measurement method (Microlife WatchBP Office Afib). On average, there were clinically minor differences in right and left arm BP values: systolic BP 134.4 vs 134.2 mmHg (p < .01) and diastolic BP 82.7 vs 82.6 mmHg (p < .01), respectively. Prevalence of significant mean systolic IAD between 10 and 15 mmHg was 7,813 (5.8%). Systolic IAD ≥ 15 mmHg 2,980 (2.2%) and diastolic IAD ≥ 10 mmHg 7,151 (5.3%). In total, there were 7,595 (5.6%) and 8,548 (6.3%) participants with BP above the 140/90 mmHg threshold in only the left or right arm, respectively. Prevalence of participants with elevated BP on one arm only was highest in patients with a systolic IAD ≥ 15 mmHg; 19.1% and 13.7%, for left and right arm, respectively. This study shows that a substantial prevalence of IAD exists in Indian primary care patients. BP is above the diagnostic threshold for hypertension in one arm only for 6% of participants. These findings emphasize the importance of undertaking bilateral BP measurement in routine clinical practice.

Inter-arm blood pressure difference and cardiovascular risk estimation in primary care

BACKGROUND

Systolic inter-arm differences (IAD) in blood pressure (BP) contribute independently to cardiovascular risk estimates; this can be used to refine predicted risk and guide personalised interventions.

AIM

To model the effect of accounting for IAD in cardiovascular risk estimation in a primary care population free of pre-existing cardiovascular disease.

DESIGN AND SETTING

Cross-sectional analysis of people aged 40-75 years attending National Health Service (NHS) Health Checks in one general practice in England.

METHOD

Simultaneous bilateral BP measurements were made during Health Checks. QRISK2, ASCVD and Framingham cardiovascular risk scores were calculated before and after adjustment for IAD using previously published hazard ratios. Reclassification across guideline-recommended intervention thresholds was analysed.

RESULTS

Data for 334 participants were analysed. Mean (standard deviation) QRISK2, ASCVD and Framingham scores were 8.0 (6.9), 6.9 (6.5) and 10.7 (8.1) respectively rising to 8.9 (7.7), 7.1 (6.7) and 11.2 (8.5) after adjustment for IAD. 13 (3.9%) participants were reclassified from below to above the 10% QRISK2 threshold, 3 (0.9%) for the ASCVD 10% threshold and 9 (2.7%) for the Framingham 15% threshold.

CONCLUSION

Knowledge of IAD can be used to refine cardiovascular risk estimates in primary care. By accounting for IAD, recommendations of interventions for primary prevention of cardiovascular disease can be personalised and treatment offered to those at greater than average risk. When assessing elevated clinic BP readings, both arms should be measured to allow fuller estimation of cardiovascular risk.

Associations Between Systolic Interarm Differences in Blood Pressure and Cardiovascular Disease Outcomes and Mortality: Individual Participant Data Meta-Analysis, Development and Validation of a Prognostic Algorithm: The INTERPRESS-IPD Collaboration

Systolic interarm differences in blood pressure have been associated with all-cause mortality and cardiovascular disease. We undertook individual participant data meta-analyses to (1) quantify independent associations of systolic interarm difference with mortality and cardiovascular events; (2) develop and validate prognostic models incorporating interarm difference, and (3) determine whether interarm difference remains associated with risk after adjustment for common cardiovascular risk scores. We searched for studies recording bilateral blood pressure and outcomes, established agreements with collaborating authors, and created a single international dataset: the Inter-arm Blood Pressure Difference - Individual Participant Data (INTERPRESS-IPD) Collaboration. Data were merged from 24 studies (53 827 participants). Systolic interarm difference was associated with all-cause and cardiovascular mortality: continuous hazard ratios 1.05 (95% CI, 1.02-1.08) and 1.06 (95% CI, 1.02-1.11), respectively, per 5 mm Hg systolic interarm difference. Hazard ratios for all-cause mortality increased with interarm difference magnitude from a ≥5 mm Hg threshold (hazard ratio, 1.07 [95% CI, 1.01-1.14]). Systolic interarm differences per 5 mm Hg were associated with cardiovascular events in people without preexisting disease, after adjustment for Atherosclerotic Cardiovascular Disease (hazard ratio, 1.04 [95% CI, 1.00-1.08]), Framingham (hazard ratio, 1.04 [95% CI, 1.01-1.08]), or QRISK cardiovascular disease risk algorithm version 2 (QRISK2) (hazard ratio, 1.12 [95% CI, 1.06-1.18]) cardiovascular risk scores. Our findings confirm that systolic interarm difference is associated with increased all-cause mortality, cardiovascular mortality, and cardiovascular events. Blood pressure should be measured in both arms during cardiovascular assessment. A systolic interarm difference of 10 mm Hg is proposed as the upper limit of normal. Registration: URL: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42015031227.

Systolic inter-arm blood pressure difference and risk of cognitive decline in older people: a cohort study

BACKGROUND

Systolic inter-arm difference in blood pressure (IAD) and cognitive decline are both associated with cardiovascular disease; therefore, it was hypothesised that IAD may be predictive of cognitive decline.

AIM

To examine associations of IAD with cognitive decline in a community population.

DESIGN AND SETTING

A prospective study of older Italian adults enrolled in the InCHIANTI study.

METHOD

Univariable and multivariable associations of IAD were explored with declines in mini mental state examination (MMSE) scores, Trail Making Test A and B scores, and a composite outcome representing substantial decline in any of these scores. Backward stepwise regression was used to adjust observed associations of IAD with cognitive decline.

RESULTS

The rate of decline for MMSE scores in 1133 participants was greater with IAD ≥5 mmHg or ≥10 mmHg. On univariable analyses continuous IAD was associated with the composite outcome (odds ratio [OR] 1.16 per 5 mmHg of IAD, 95% confidence interval [CI] = 1.02 to 1.31). Substantial decline in MMSE score was seen with IAD ≥5 mmHg (OR 1.41, 95% CI = 1.03 to 1.93), and in the composite outcome with IAD ≥5 mmHg (OR 1.44, 95% CI = 1.10 to 1.89) or ≥10 mmHg (OR 1.39, 95% CI = 1.03 to 1.88). After multivariable adjustment, an IAD ≥ 5 mmHg remained associated with reductions in the composite outcome, reflecting declining cognitive performance (OR 1.46, 95% CI = 1.05 to 2.03).

CONCLUSION

An IAD ≥5 mmHg is associated with cognitive decline in a representative older population. Given that systolic inter-arm differences in blood pressure are easily measured, confirmation of these findings could inform individualised treatment for the prevention of cognitive decline and dementia.

Detecting Risk Of Postural hypotension (DROP): derivation and validation of a prediction score for primary care

OBJECTIVES

Falls are a common problem in older people. Postural hypotension contributes to falls but is often asymptomatic. In the absence of symptoms, postural hypotension is only infrequently checked for in clinical practice. We undertook this study to derive, validate and explore the prospective associations of a prediction tool to identify people likely to have unrecognised postural hypotension.

DESIGN AND SETTING

Cross-sectional and prospective multivariable cohort analysis.

PARTICIPANTS

1317 participants of the Invecchiare in Chianti study, a population-based cohort representative of the older Italian population.

PRIMARY OUTCOME MEASURES

Predictive value of score to suggest presence of postural hypotension.

METHODS

Subjects were randomised 1:1 to derivation or validation cohorts. Within the derivation cohort, univariable associations for candidate predictors of postural hypotension were tested. Variables with p<0.1 entered multivariable linear regression models. Factors retaining multivariable significance were incorporated into unweighted and weighted Detecting Risk Of Postural hypotension (DROP) scores. These scores were tested in the validation cohort against prediction of postural hypotension, cognitive decline and mortality over 9 years of follow-up.

RESULTS

Postural hypotension was present in 203 (15.4%) of participants. Factors predicting postural hypotension were: digoxin use, Parkinson's disease, hypertension, stroke or cardiovascular disease and an interarm systolic blood pressure difference. Area under the curve was consistent at 0.65 for all models, with significant ORs of 1.8 to 2.4 per unit increase in score for predicting postural hypotension. For a DROP score ≥1, five cases need to be tested to identify one with postural hypotension.Increasing DROP scores predicted mortality (OR 1.8 to 2.8 per unit rise) and increasing rates of decline of Mini Mental State Examination score (analysis of variance p<0.001) over 9 years of follow-up.

CONCLUSIONS

The DROP score provides a simple method to identify people likely to have postural hypotension and increased risks to health who require further evaluation.

Associations between interarm differences in blood pressure and cardiovascular disease outcomes: protocol for an individual patient data meta-analysis and development of a prognostic algorithm

INTRODUCTION

Individual cohort studies in various populations and study-level meta-analyses have shown interarm differences (IAD) in blood pressure to be associated with increased cardiovascular and all-cause mortality. However, key questions remain, such as follows: (1) What is the additional contribution of IAD to prognostic risk estimation for cardiovascular and all-cause mortality? (2) What is the minimum cut-off value for IAD that defines elevated risk? (3) Is there a prognostic value of IAD and do different methods of IAD measurement impact on the prognostic value of IAD? We aim to address these questions by conducting an individual patient data (IPD) meta-analysis.

METHODS AND ANALYSIS

This study will identify prospective cohort studies that measured blood pressure in both arms during recruitment, and invite authors to contribute IPD datasets to this collaboration. All patient data received will be combined into a single dataset. Using one-stage meta-analysis, we will undertake multivariable time-to-event regression modelling, with the aim of developing a new prognostic model for cardiovascular risk estimation that includes IAD. We will explore variations in risk contribution of IAD across predefined population subgroups (eg, hypertensives, diabetics), establish the lower limit of IAD that is associated with additional cardiovascular risk and assess the impact of different methods of IAD measurement on risk prediction.

ETHICS AND DISSEMINATION

This study will not include any patient identifiable data. Included datasets will already have ethical approval and consent from their sponsors. Findings will be presented to international conferences and published in peer reviewed journals, and we have a comprehensive dissemination strategy in place with integrated patient and public involvement.

PROSPERO REGISTRATION NUMBER

CRD42015031227.