White coat hypertension: time for action

Pediatric hypertension: Review of the definition, diagnosis, and initial management

Pediatric hypertension (HTN) is a significant and growing health concern. While previously thought to be an uncommon condition in the pediatric population, recent studies have shown an increase in incidence, which is largely due to the obesity epidemic. Accordingly, primary or idiopathic HTN has become more prevalent compared to secondary causes of HTN. The incidence of hypertension is about 3.5%; however, it may be higher as HTN can be missed during routine pediatric well visits. Since childhood HTN frequently tracks into adulthood and is a risk factor for both cardiovascular disease and progression of renal disease; early diagnosis and management of this condition is essential. In this review, we will discuss the approach of a pediatric nephrologist for evaluation and management of pediatric HTN.

Decoding white coat hypertension

There is arguably no less understood or more intriguing problem in hypertension that the "white coat" condition, the standard concept of which is significantly blood pressure reading obtained by medical personnel of authoritative standing than that obtained by more junior and less authoritative personnel and by the patients themselves. Using hospital-initiated ambulatory blood pressure monitoring, the while effect manifests as initial and ending pressure elevations, and, in treated patients, a low daytime profile. The effect is essentially systolic. Pure diastolic white coat hypertension appears to be exceedingly rare. On the basis of the studies, we believe that the white coat phenomenon is a common, periodic, neuro-endocrine reflex conditioned by anticipation of having the blood pressure taken and the fear of what this measurement may indicate concerning future illness. It does not change with time, or with prolonged association with the physician, particularly with advancing years, it may be superimposed upon essential hypertension, and in patients receiving hypertensive medication, blunting of the nighttime dip, which occurs in about half the patients, may be a compensatory mechanisms, rather than an indication of cardiovascular risk. Rather than the blunted dip, the morning surge or the widened pulse pressure, cardiovascular risk appears to be related to elevation of the average night time pressure.

Central pressures and central hemodynamic values in white coat hypertensives are closer to those of normotensives than to those of controlled hypertensives for similar age, gender, and 24-h and nocturnal blood pressures

INTRODUCTION

There is disagreement whether white coat hypertensives (WCH) have different hemodynamic and structural characteristics compared to normotensives (NT) and hypertensives (HT).

METHODS

We compared cardiovascular prognostic markers (pulse wave velocity [PWV] and aortic stiffness index [ASI]) and data on central hemodynamics and central pressures (augmentation index [AIx], augmentation pressure [AugP] and pulse pressure amplification [PPA]) from aortic pulse wave analysis between NT (n=175), WCH (n=315) and treated HT (n=691), all with 24-h blood pressure (BP) <130/80 and nocturnal BP <120/70 mmHg after matching for age, gender, body mass index (BMI) and and nocturnal BP. The groups were also compared separately in terms of 24-h systolic BP <120 mmHg and 120-129 mmHg.

RESULTS

The percentage of non-dippers was 40.1% in NT, 34.5% in WCH and 38.3 in HT. For similar 24-h and nocturnal systolic BP (NT 109/64±7/5, WCH 110/66±7/6, HT 109/64±7/5 mmHg), aortic stiffness was greater in HT (n=691, PWV 10.8±2.6 m/s and ASI 0.33±0.16, p<0.01) than in WCH (n=316, PWV 9.7±2.4 m/s and ASI 0.28±0.17) and NT (n=175, PWV 9.5±2.0 m/s and ASI 0.29±0.15); AugP and AIx were higher (p<0.01) in HT (13.9±8.2 and 29.6±12.6 mmHg) than in WCH (11.5±8.5 mmHg and 24.9±15.2) and NT (11.0±6.4 mmHg and 26.6±11.5). PPA was lower (p<0.01) in HT (11.3±5.5 mmHg) than in WCH (13.2±7.1 mmHg) and in NT (12.4±4.9 mmHg). The findings were similar when the 24-h systolic BP <120 mmHg and 120-129 mmHg subgroups were analyzed separately.

CONCLUSION

Our data suggest that for similar age, gender distribution, BMI, and 24-h and nocturnal BP, aortic stiffness, central aortic pressures and wave reflection in WCH are closer to those of NT than to those with treated HT. This supports the idea that white coat hypertension may be a more benign condition than treated hypertension for similar 24-h and particularly nocturnal BP levels.

Toward a definition of masked hypertension and white-coat hypertension among hemodialysis patients

BACKGROUND AND OBJECTIVES

Among people with essential hypertension, ambulatory BP measurement is superior to BP obtained in the clinic in predicting cardiovascular outcomes. In part, this is because it can detect white-coat hypertension and masked hypertension. Whether the same is true for hemodialysis patients is not known.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Using a threshold of 140/80 mmHg for median midweek dialysis-unit BP and 135/85 mmHg for 44-hour ambulatory BP, we defined four categories of BP: sustained normotension (SN), white-coat hypertension (WCH), masked hypertension (MHTN), and sustained hypertension (SHTN).

RESULTS

Among 355 long-term hemodialysis patients, the prevalence of SN was 35%, WCH 15%, MHTN 15%, and SHTN 35%. Over a mean follow-up of 29.6 (SD 21.7) months, 102 patients died (29%), yielding a crude mortality rate of 121/1000 patient-years. Unadjusted and multivariate-adjusted analyses showed increasing all-cause mortality with increasing severity of hypertension (unadjusted hazard ratios from SN, WCH, MHTN, SHTN: 1, 1.12, 1.70, 1.80, respectively [P for trend < 0.01]; adjusted hazard ratios: 1, 1.30, 1.36, 1.87, respectively [P for trend 0.02]). When a predialysis BP threshold of 140/90 mmHg was used to classify patients into BP categories, the prevalence of SN was 24%, WCH 26%, MHTN 4%, and SHTN 47%. Hazard ratios for mortality were similar when compared with median midweek dialysis-unit BP.

CONCLUSIONS

As in the essential hypertension population, MHTN and WCH have prognostic significance. The prognostic value of BP obtained in the dialysis unit can be refined with ambulatory BP monitoring.

Reasons for not intensifying medications: differentiating "clinical inertia" from appropriate care

BACKGROUND

"Clinical inertia" has been defined as inaction by physicians caring for patients with uncontrolled risk factors such as blood pressure. Some have proposed that it accounts for up to 80% of cardiovascular events, potentially an important quality problem. However, reasons for so-called clinical inertia are poorly understood.

OBJECTIVE

To derive an empiric conceptual model of clinical inertia as a subset of all clinical inactions from the physician perspective.

METHODS

We used Nominal Group panels of practicing physicians to identify reasons why they do not intensify medications when seeing an established patient with uncontrolled blood pressure.

MEASUREMENTS AND MAIN RESULTS

We stopped at 2 groups (N = 6 and 7, respectively) because of the high degree of agreement on reasons for not intensifying, indicating saturation. A third group of clinicians (N = 9) independently sorted the reasons generated by the Nominal Groups. Using multidimensional scaling and hierarchical cluster analysis, we translated the sorting results into a cognitive map that represents an empirically derived model of clinical inaction from the physician's perspective. The model shows that much inaction may in fact be clinically appropriate care.

CONCLUSIONS/RECOMMENDATIONS

Many reasons offered by physicians for not intensifying medications suggest that low rates of intensification do not necessarily reflect poor quality of care. The empirically derived model of clinical inaction can be used as a guide to construct performance measures for monitoring clinical inertia that better focus on true quality problems.

Sequential follow-up clinic and ambulatory blood pressure evaluation in a low risk population of white-coat hypertensive patients and in normotensives

BACKGROUND

In subjects with white-coat hypertension (WCH) it is unclear how ambulatory blood pressure (ABPM) progresses over time and whether they exhibit an increased cardiovascular risk.

METHODS

We prospectively evaluated the transition of clinic and ABPM values in 39 clinic and ABPM normotensive subjects (NT) (clinic BP<140/90 mmHg and awake BP<130/85 mmHg, ages 43.4+/-2.6 y) and in 79 untreated subjects (47.2+/-2.4 y) with WCH (clinic BP>140/90, awake ABP<130/85 mmHg) with no other major cardiovascular risk factors. Ambulatory blood pressure was evaluated at baseline and on at least two further occasions during follow-up.

RESULTS

At baseline all subjects were untreated and groups did not differ on values of metabolic parameters, BMI, left ventricular mass index, and ABPM values. Subjects were revaluated for ABPM half way through and at the end of follow-up, 35+/-3 and 86+/-4 months in NT and 49+/-4 and 90+/-4 months in WCH. Thirty-six WCH were on antihypertensive treatment (AH) after baseline until the end of follow-up (WCH-tr), whereas 43 WCH (WCH-untr) were free from AH throughout the study. In a similar way all groups showed a significant (p<0.01) progressive increase in 24-h ABPM systolic blood pressure (SBP)/diastolic blood pressure (DBP) from baseline throughout the follow-up in NT (+4.9/2.1+/-0.8/0.9 mmHg), average annual increase of 0.72/0.37 mmHg/y, in WCH-tr (+ 5.0/1.2+/-1.1/1.5 mmHg), average annual increase of 0.66/0.31 mmHg/y and in WCH-untr (+5.4/3.2+/-0.9/1.1 mmHg), average annual increase of 0.74/0.39 mmHg/y. During the follow-up office SBP/DBP (mmHg) significantly rose in NT (+5.7/3.9) but was reduced in WCH-tr (-7.8/5.2) and in WCH-untr (-4.7/1.1). Development of ambulatory hypertension (daytime BP >130 and/or >85 mmHg) occurred in 15.4% (6/39) of NT, in 22.7% (8/36) of WCH-tr and in 26.1% (11/43) of WCH-untr (NS). First cardiovascular events recorded were three in subjects with WCH and none in NT.

CONCLUSIONS

After 7.4 years of follow-up, both the progressive increase in ABPM and the rate of transition to ambulatory hypertension in subjects with WCH (either treated or untreated), who were selected under strict criteria were similar to that of normotensive subjects. Also there was no evidence that WCH exhibited a clear higher risk of development cardiovascular events.

Hypertension is frequently present in patients with reflux esophagitis or Barrett's esophagus but not in those with non-ulcer dyspepsia

BACKGROUND: Elevated mortality due to cardiovascular disease has been reported for patients with Barrett's esophagus (BE). We compared the prevalence of risk factors for cardiovascular disease in patients with BE, reflux esophagitis (RE), and non-ulcer dyspepsia (NUD) with that of the general population. METHODS: Patients with upper gastrointestinal complaints and BE, RE, or NUD were compared with a matched cohort from the general population using a questionnaire and blood pressure and cholesterol measurements. RESULTS: Hypertension occurred more frequently in patients with BE (odds ratio 5.1, P<0.0001) and RE (odds ratio 3.8, P<0.001), but not in those with NUD. Serum total cholesterol was higher in BE (P=0.02) and borderline in RE (P=0.06) but not in NUD. Mean HDL cholesterol levels, body mass index, and smoking did not differ. CONCLUSIONS: This study suggests that BE and RE found at diagnostic endoscopy are associated with an increased prevalence of hypertension and a higher total cholesterol level than in the general population. If so, this would explain the increased mortality during the follow-up of BE patients, and it should be taken into account when designing or evaluating follow-up studies of BE.

Cost analysis of ambulatory blood pressure monitoring in initiating antihypertensive drug treatment in Australian general practice

OBJECTIVE

To compare the cost of ambulatory blood pressure monitoring (ABPM) with the putative savings made through treatment avoided by identification and non-treatment of those with "white coat" hypertension.

DESIGN

A cost analysis based on a model of four alternative strategies (no ABPM, yearly, two-yearly, or three-yearly monitoring) over a seven-year period applied to a case series from Australian general practice.

PARTICIPANTS

62 patients newly diagnosed by their GPs as having hypertension and requiring drug treatment.

MAIN OUTCOME MEASURES

The proportion of patients shown to not need treatment. The discounted costs to the Pharmaceutical Benefits Scheme, Medical Benefits Scheme and patients.

RESULTS

16 of 62 patients (26%; 95% CI, 15%-37%) were normotensive on ABPM and did not require treatment. All monitoring strategies are more expensive in the first year, but the initial costs are offset by year 3 and the monitoring strategies are cost saving thereafter. Sensitivity analysis shows that this result holds across a range of costs of pharmacotherapy and proportion of patients with white coat hypertension.

CONCLUSION

The additional costs of 24-hour ABPM in the first year are offset by savings associated with patients with white coat hypertension who would otherwise have been treated.

Elevated blood pressure in subjects with lipodystrophy

OBJECTIVES

To assess the prevalence of elevated blood pressure in patients with lipodystrophy.

DESIGN

Case-control study.

PARTICIPANTS

Forty-two patients with abnormal body fat (100%) and serum lipids (86%) (HIV-positive cohort) were matched by age and sex to 42 HIV-positive controls without previously diagnosed lipodystrophy and to 13 HIV-negative controls.

SETTING

Tertiary care, university-based, fully dedicated HIV clinic.

MAIN OUTCOME MEASURES

Frequency and magnitude of elevated blood pressure during highly active antiretroviral therapy.

RESULTS

There were 23 +/- 16 and 22 +/- 12 blood pressure measurements recorded per subject over 21 +/- 11 and 22 +/- 11 months for the HIV-positive cohort and HIV-positive controls, respectively. Three or more elevated readings occurred in 74% of the cohort and in 48% of the HIV-positive controls (P = 0.01) and accounted for 38 +/- 25% versus 22 +/- 26% (P = 0.01) of the total readings, respectively. The average of the three highest systolic readings (153 +/- 17 versus 144 +/- 15 mmHg; P = 0.01) and diastolic readings (92 +/- 10 versus 87 +/- 9 mmHg; P = 0.01) was greater for the cohort than for the HIV-positive controls. Family history of hypertension was more common in the cohort than in the controls but accounted for only 13% of the log odds ratio value for elevated blood pressure in the cohort. Systolic blood pressure was correlated with waist-to-hip ratios in the cohort (r = 0.45; P = 0.003) but not in the HIV controls (r = 0.06; P = 0.68) and tended to be related to fasting triglycerides (r = 0.34; P = 0.052) in subjects with HIV.

CONCLUSIONS

Elevated blood pressure may be linked to the metabolic disorders occurring in patients with HIV, as in the dysmetabolic syndrome.

Silent and clinically overt stroke in older Japanese subjects with white-coat and sustained hypertension

OBJECTIVES

We investigated whether white-coat hypertension is a risk factor for stroke in relation to silent cerebral infarct (SCI) in an older Japanese population.

BACKGROUND

It remains uncertain whether white-coat hypertension in older subjects is a benign condition or is associated with an increased risk of stroke.

METHODS

We studied the prognosis for stroke in 958 older Japanese subjects (147 normotensives [NT], 236 white-coat hypertensives [WCHT] and 575 sustained hypertensives [SHT]) in whom ambulatory blood pressure monitoring was performed in the absence of antihypertensive treatment. In 585 subjects (61%), we also assessed SCI using brain magnetic resonance imaging.

RESULTS

Silent cerebral infarcts were found in 36% of NT (n = 70), 42% of WCHT (n = 154), and 53% of SHT (n = 361); multiple SCIs (the presence of > or =2 SCIs) were found in 24% of NT, 25% of WCHT and 39% of SHT. During a mean 42-month follow-up period, clinically overt strokes occurred in 62 subjects (NT: three [2.0%]; WCHT: five [2.1%]; SHT: 54 [9.4%]), with 14 fatal cases (NT: one [0.7%]; WCHT: 0 [0%]; SHT: 13 [2.3%]). A Cox regression analysis showed that age (p = 0.0001) and SHT (relative risk, [RR] [95% confidence interval, CI]: 4.3 [1.3-14.2], p = 0.018) were independent stroke predictors, whereas WCHT was not significant. When we added presence/absence of SCI at baseline into this model, the RR (95% CI) for SCI was 4.6 (2.0-10.5) (p = 0.003) and that of SHT was 5.5 (1.8-18.9) versus WCHT (p = 0.004) and 3.8 (0.88-16.7) versus NT (p = 0.07).

CONCLUSIONS

In older subjects the incidence of stroke in WCHT is similar to that of NT and one-fourth the risk in SHT. Although SCI is a strong predictor of stroke, the difference in stroke prognosis between SHT and WCHT was independent of SCI. It is clinically important to distinguish WCHT from SHT even after assessment of target organ damage in the elderly.

Modern approaches to blood pressure measurement

BACKGROUND

Blood pressure (BP) is usually measured by conventional sphygmomanometry. Although apparently simple, this procedure is fraught with many potential sources of error. This review focuses on two alternative techniques of BP measurement: ambulatory monitoring and self measurement.

REVIEW

BP values obtained by ambulatory monitoring or self measurement are characterised by high reproducibility, are not subject to digit preference or observer bias, and minimise the transient rise of the blood pressure in response to the surroundings of the clinic or the presence of the observer, the so called white coat effect. For ambulatory monitoring, the upper limits of systolic/diastolic normotension in adults include 130/80 mm Hg for the 24 hour BP and 135/85 and 120/70 mm Hg for the daytime BP and night time BP, respectively. For the the self measured BP these thresholds include 135/85 mm Hg. Automated BP measurement is most useful to identify patients with white coat hypertension. Whether or not white coat hypertension predisposes to sustained hypertension remains debated. However, outcome is better correlated with the ambulatory BP than with the conventional BP. In patients with white coat hypertension, antihypertensive drugs lower the BP in the clinic, but not the ambulatory BP, and also do not improve prognosis. Ambulatory BP monitoring is also better than conventional BP measurement in assessing the effects of treatment. Ambulatory BP monitoring is necessary to diagnose nocturnal hypertension and is especially indicated in patients with borderline hypertension, elderly patients, pregnant women, patients with treatment resistant hypertension, and also in patients with symptoms suggestive of hypotension.

CONCLUSIONS

The newer techniques of BP measurement are now well established in clinical research, for diagnosis in clinical practice, and will increasingly make their appearance in occupational and environmental medicine.