Misclassification of blood pressure of Vietnamese adults when only a single measurement is used.

A single clinic measurement of blood pressure (BP) may be common in low- and middle-income countries because of limited medical resources. This study aimed to examine the potential misclassification error when only one BP measurement is used. Participants (n = 14,706, 53.5% females) aged 25-64 years were selected by multistage stratified cluster sampling from eight provinces, each representing one of the eight geographical regions of Vietnam. Measurements were made using the World Health Organization STEPS protocols. Data were analyzed using complex survey methods. For systolic BP, 62.7% had a higher first reading whereas 30.0% had a lower first reading, and 27.3% had a reduction of at least 5 mmHg whereas 9.6% had an increase of at least 5 mmHg. Irrespective of direction of change, increased variability in BP was associated with greater age, urban living, greater body size and fatness, reduced physical activity levels, elevated glucose, and raised total cholesterol. These measurement variations would lead to substantial misclassification in diagnosis of hypertension based on a single reading because almost 20% of subjects would receive a different diagnosis based on the mean of two readings.

Influence of blood pressure level and age on within-visit blood pressure variability in children and adolescents.

Blood pressure (BP) is variable in children and this could affect BP assessment, but the magnitude of within-visit BP variability (BPV) over consecutive measurements has never been investigated. This study aimed to determine the direction and magnitude of, and factors affecting, within-visit BPV in children and adolescents. BP was recorded among 3047 children (aged 12 years [95%CI 12, 13], males 52%) from the 2011-2013 Australian Health Survey. BPV was defined as the absolute difference (∆SBPABS) between the first (SBP1) and second systolic BP (SBP2) and the overall variability in three measures when available (SBPV). On average, ∆SBPABS was 6.7 mmHg (95%CI 6.3, 7.0) and SBPV was 8.2% (95%CI 7.8, 8.6). ∆SBPABS was greater with higher BP levels but lower with older age. From first to second measurements, SBP decreased in 58% (95%CI 56, 60), did not change in 10% (95%CI 9, 12), and increased in 32% (95%CI 29, 34) of the population. CONCLUSIONS: BP is highly variable in children and adolescents, with the magnitude of variability being associated with both age and BP level. SBP increases on repeat measurement in a substantial proportion of the population. The optimal protocol of BP assessment to address this increased BPV needs to be determined. What is Known: • Diagnosis of elevated blood pressure (BP) is based on strict probabilistic criteria, the difference between the 90th (pre-hypertension) and 95th (hypertension) percentiles only being 3-4 mmHg. • BP variability could affect BP classification among children and adolescents. What is New: • The magnitude of BP change among children and adolescents is highly affected by BP level and age. • BP does not always drop on consecutive measurements, and evidence-based BP assessment protocols should be established to avoid misdiagnosis of hypertension.

Identification of the Optimal Protocol for Automated Office Blood Pressure Measurement Among Patients With Treated Hypertension.

BACKGROUND: Automated office blood pressure (AOBP) involving repeated, unobserved blood pressure (BP) readings during one clinic visit is recommended for in-office diagnosis and assessment of hypertension. However, the optimal AOBP protocol to determine BP control in the least amount of time with the fewest BP readings is yet to be determined and was the aim of this study. METHODS: One hundred and eighty-nine patients (mean age 62.8 ± 12.1 years; 50.3% female) with treated hypertension referred to specialist clinics at 2 sites underwent AOBP in a quiet room alone. Eight BP measurements were taken starting immediately after sitting and then at 2-minute intervals (15 minutes total). The optimal AOBP protocol was defined by the smallest mean difference and highest intraclass correlation coefficient (ICC) compared with daytime ambulatory BP (ABP). The same BP device (Mobil-o-graph, IEM) was used for both AOBP and daytime ABP. RESULTS: Average 15-minute AOBP and daytime ABP were 134 ± 22/82 ± 13 and 137 ± 17/83 ± 11 mm Hg, respectively. The optimal AOBP protocol was derived within a total duration of 6 minutes from the average of 2 measures started after 2 and 4 minutes of seated rest (systolic BP: mean difference (95% confidence interval) 0.004(-2.21, 2.21) mm Hg, P = 1.0; ICC = 0.81; diastolic BP: mean difference 0.37(-0.90, 1.63) mm Hg, P = 0.57; ICC = 0.86). AOBP measures taken after 8 minutes tended to underestimate daytime ABP (whether as a single BP or the average of more than 1 BP reading). CONCLUSIONS: Only 2 AOBP readings taken over 6 minutes (excluding an initial reading immediately after sitting) may be needed to be comparable with daytime ABP.

Methodological factors affecting quantification of blood pressure variability: a scoping review.

OBJECTIVES: Blood pressure (BP) variability (BPV) may offer independent prognostic information. However, data supporting this notion are inconsistent, and this may be due to the wide variety of methodologies used for measuring BPV. A systematic analysis on the effect of BPV methodologies on BPV itself has never been undertaken and was the aim of this study. We also sought to determine the effect of participant characteristics on BPV. METHODS: A scoping review process was used to identify the effect of BPV methodologies on BPV magnitude. Key methodological factors assessed were the number of BP readings or visits used to quantify BPV and the duration of BP monitoring. In addition, the relationship between age and mean BP level on BPV was investigated. Analyses were performed across studies that measured BPV over the short-term (using 24-h BP), mid-term (using home BP in the morning, evening or day-to-day) and long-term (using visit-to-visit clinic BP). RESULTS: Data were extracted from 96 studies. The number of BP readings and visits used to quantify BPV were positively associated with mid-term and long-term BPV. Duration was weakly associated with mid-term (morning) BPV. Age was positively associated with long-term and mid-term (day-to-day), but not short-term BPV. Mean BP level was positively associated with BPV, except mid-term BPV (morning and evening). CONCLUSION: The methodology used to quantify BPV, as well as age and mean BP level, affects the magnitude of BPV itself. This highlights the need to standardize BPV protocols, particularly regarding the number of BP readings and visits.

Age-dependent changes in blood pressure over consecutive office measurements: impact on hypertension diagnosis and implications for international guidelines.

OBJECTIVES: Based on anecdotal belief that blood pressure (BP) drops over consecutive measurements, guidelines recommend discarding the first BP reading (Canadian Hypertension Education Program guidelines) or take only one reading if SBP less than 140 mmHg (National Institute for Health and Care Excellence). However, the extent to which SBP fluctuations affect BP classification as well as the potential effect of age are unknown. We sought to assess the change in SBP classification over consecutive measurements following different guidelines, among younger (<50 years) and older individuals (≥50 years). Furthermore, we aimed to investigate the direction of the change in SBP over consecutive measurements (increase or decrease) and the impact of age on SBP differences. METHODS: BP was measured among 20 716 adults from a general population. SBP was classified using the first reading (normal SBP or hypertension) and compared with the average SBP using different guideline protocols (reclassification). RESULTS: Reclassification from normal SBP to hypertension was greatest with Canadian Hypertension Education Program guidelines (3% younger, 12% older individuals) and reclassification from hypertension to normal SBP was greatest with National Institute for Health and Care Excellence guidelines (70% younger, 44% older individuals). SBP increased between the first two measures in 37%, decreased in 56% and did not change in 7% of the population. Age had a strong interaction with SBP level (P < 0.0001) so that younger individuals exhibited greater SBP differences over repeated measures. CONCLUSION: This study highlights the need for an improvement in the evidence-base regarding the best way to assess office BP for correct hypertension diagnosis.

Effectiveness of Vitamin D Supplementation for Cardiovascular Health Outcomes.

There is a plausible physiological theory, supported by many observational studies, that vitamin D supplementation should be effective for improving cardiovascular end points, such as blood pressure (BP), large artery stiffness, atherosclerosis, endothelial function and clinical events. However, results from randomised controlled trials (RCTs) have been inconsistent. In this review, we evaluated the evidence regarding the effectiveness of vitamin D supplementation for cardiovascular surrogate and hard clinical end points. RCTs were assessed in terms of sample size, duration of supplementation, baseline vitamin D level inclusion criteria (i.e., absence of vitamin D deficiency), dosage of vitamin D and population under investigation. Forty-five RCTs were identified. Eight RCTs with BP and 6 RCTs with large artery stiffness as the end points were found to comply with guidelines for the optimal design of clinical trials evaluating nutrient effects. Only 2 of the RCTs with an optimal design were effective in decreasing BP with vitamin D supplementation, although these were of moderate sample size (<150) and very short duration (8 weeks for both), whilst no RCT was effective in reducing large artery stiffness. Similar results were observed for atherosclerotic and endothelial function markers as end points. Only 1 RCT reported cardiovascular events as an end point and found neither increased nor decreased incident cardiovascular events over 7 years of follow-up. In conclusion, results from published RCTs indicate that vitamin D supplementation is ineffective in improving cardiovascular health among various patient populations, including in the presence or absence of vitamin D deficiency.

Associations of blood pressure variability and retinal arteriolar diameter in participants with type 2 diabetes.

Blood pressure variability is associated with macrovascular complications and stroke, but its association with the microcirculation in type II diabetes has not been assessed. This study aimed to determine the relationship between blood pressure variability indices and retinal arteriolar diameter in non-diabetic and type II diabetes participants. Digitized retinal images were analysed to quantify arteriolar diameters in 35 non-diabetic (aged 52 ± 11 years; 49% male) and 28 type II diabetes (aged 61 ± 9 years; 50% male) participants. Blood pressure variability was derived from 24-h ambulatory blood pressure. Arteriolar diameter was positively associated with daytime rate of systolic blood pressure variation (p = 0.04) among type II diabetes participants and negatively among non-diabetics (p = 0.008; interaction p = 0.001). This finding was maintained after adjusting for age, sex, body mass index and mean daytime systolic blood pressure. These findings suggest that the blood pressure variability-related mechanisms underlying retinal vascular disease may differ between people with and without type II diabetes.

Blood Pressure Variability and Prediction of Target Organ Damage in Patients With Uncomplicated Hypertension.

BACKGROUND: The average of multiple blood pressure (BP) readings (mean BP) independently predicts target organ damage (TOD). Observational studies have also shown an independent relationship between BP variability (BPV) and TOD, but there is limited longitudinal data. This study aimed to determine the effects of changes in mean BP levels compared with BPV on left ventricular mass index (LVMI) and aortic pulse wave velocity (aPWV). METHODS: Mean BP levels (research-protocol clinic BP (clinic BP), 24-hour ambulatory BP, and 7-day home BP) and BPV were assessed in 286 patients with uncomplicated hypertension (mean age 64±8 SD years, 53% women) over 12 months. Reading-to-reading BPV (from 24-hour ambulatory BP) and day-to-day BPV (from 7-day home BP) were assessed at baseline and 12 months, and visit-to-visit BPV (clinic BP) was assessed from 5 visits over 12 months. LVMI was measured by 3D echocardiography and aPWV with applanation tonometry. RESULTS: The strongest predictors of the changes in LVMI (ΔLVMI) were the changes in mean 24-hour systolic BPs (SBPs) (P < 0.02). Similarly, the strongest predictors of the changes in aPWV (ΔaPWV) were the changes in mean 24-hour ambulatory SBPs (P < 0.01) and the changes in mean clinic SBP (P < 0.001). However, none of the changes in BPV were independently associated with ΔLVMI or ΔaPWV (P > 0.05 for all). CONCLUSIONS: Changes in mean BP levels, but not BPV, were most relevant to changes in TOD in patients with uncomplicated hypertension. Thus, from this point of view, BPV appears to have limited clinical utility in this patient population.