Statistical analysis as a cause of white-coat hypertension

Controversies in Hypertension I: The Optimal Assessment of Blood Pressure Load and Implications for Treatment

The most important factor in treating hypertension is assessing an individual patient's true blood pressure load, the cornerstone being research-grade office determination. Office blood pressure should be supplemented with out-of-office measurement, including home and ambulatory monitoring (if available), which we consider complementary and not interchangeable. Controversy remains for initiation of treatment of white coat hypertension, where cardiovascular risk lies between normotension and sustained hypertension; antihypertensive therapy should be considered unless low cardiovascular risk, wherein pressures should be followed for progression to sustained hypertension. Available data do not support intensification of therapy for the white coat effect due to the similar cardiovascular risk to controlled hypertension. Given the higher cardiovascular risk of the masked effect, initiation of therapy for masked hypertension and intensification for masked uncontrolled hypertension are indicated, acknowledging the dearth of supporting data. Optimally, randomized controlled trials are needed to determine the benefit of treating the 4 incongruous phenotypes between office and out-of-office measurements, that is, those with white coat or masked effects. We make no recommendations regarding chronotherapy pending results of ongoing trials.

White-coat hypertension and incident end-stage renal disease in patients with non-dialysis chronic kidney disease: results from the C-STRIDE Study

Background

Controversy remains whether white coat hypertension (WCH) is associated with renal prognosis in patients with chronic kidney disease (CKD).

Methods

In the present multicenter, prospective study, we analyzed data of participants with CKD stage 1–4 from the Chinese Cohort Study of Chronic Kidney Disease (C-STRIDE). WCH was defined according to two criteria as follows: A, clinical blood pressure (BP) ≥ 140/90 mm Hg and average 24-h ambulatory BP < 130/80 mm Hg; B, clinical BP ≥ 130/80 mm Hg and daytime ambulatory BP < 130/80 mm Hg. Renal outcome was defined as initiation of renal replacement therapy. The association of WCH with renal events was evaluated by Cox regression model.

Results

A total of 1714 patients with CKD were included in the present analysis. The mean age of the population was 48.9 ± 13.8 years and 56.8% were men. The mean baseline estimated glomerular filtration rate (eGFR) was 52.2 ± 30.1 ml/min/1.73 m² and urinary protein was 1.0 (0.4, 2.4) g/day. The overall prevalence of WCH was 4.7% and 16.6% according to criteria A and B, respectively. Incidence rates of renal events were 49.58 and 26.51 according to criteria A and B, respectively, per 1000 person-years during a median follow-up of 4.8 years. After full adjustment, WCH was associated with an increased risk of renal event (criterion A: hazard ratio 2.36, 95% confidence interval 1.29–4.34; for criterion B: hazard ratio 1.90, 95% confidence interval 1.04–3.49) compared with patients with normal BP.

Conclusions

WCH is associated with a greater risk for renal events in non-dialysis dependent Chinese patients with CKD.

Long-term cardiovascular risk of white-coat hypertension with normal night-time blood pressure values

BACKGROUND

The prognostic impact of white-coat hypertension (WCHT) is still a matter of debate and controversy. Night-time blood pressure (NBP) is related strongly to cardiovascular (CV) prognosis, but this has not been considered currently in the definition of WCHT.

PATIENTS AND METHODS

We investigated the long-term CV prognosis of 2659 patients submitted at admission to 24 h-ambulatory blood pressure (BP) monitoring divided into three groups: normotension (NT) (n=812; 59% female; ageing 49±13 years), sustained hypertension (SHT) (n=1230; 56% female; ageing 51±13 years) and WCHT (n=617; 55% female; ageing 50±3 years) defined as office BP of at least 140/90 mmHg, daytime BP less than 135/85 mmHg and NBP less than 120/70 mmHg.

RESULTS

The median follow-up was 7.6 years (range: 0.4-24.4), during which a total of 257 CV events (36 fatal) occurred (46% strokes, 32% coronary and 22% others), 38 in NT, 31 in WCHT and 188 in SHT. The event rate per 100 patient-years was 0.60 in the WCHT group, 0.66 in the NT group and 2.09 in the SHT group. Cox's regression analysis adjusted for covariables showed a higher risk of CV events in patients with SHT than WCHT [hazard ratio (HR)=2.230, 95% confidence interval: 1.339-3.716, P=0.002], whereas there was no difference between WCHT and NT groups. Event-free survival was significantly different from SH versus WCHT and NT groups. Within the group of WCHT, 29% of patients received sustained antihypertensive medication during the follow-up, but the HR of CV events between WCHT either treated or not treated did not differ: HR=0.76 (95% confidence interval: 0.37-1.51, P=0.42).

CONCLUSION

In patients with WCHT defined by normal daytime and NBP values, the risk of CV events was significantly lower than that of SHT and similar to that of NT patients, suggesting that NBP should be included in the WCHT definition and in its prognostic stratification.

Comparison of awake ambulatory blood pressure and automated office blood pressure using linear regression analysis in untreated patients in routine clinical practice

The recent American hypertension guidelines recommended a threshold of 130/80 mmHg to define hypertension on the basis of office, home or ambulatory blood pressure (BP). Despite recognizing the potential advantages of automated office (AO)BP, the recommendations only considered conventional office BP, without providing supporting evidence and without taking into account the well documented difference between office BP recorded in research studies versus routine clinical practice, the latter being about 10/7 mmHg higher. Accordingly, we examined the relationship between AOBP and awake ambulatory BP, which the guidelines considered to be a better predictor of future cardiovascular risk than office BP. AOBP readings and 24-hour ambulatory BP recordings were obtained in 514 untreated patients referred for ambulatory BP monitoring in routine clinical practice. The relationship between mean AOBP and mean awake ambulatory BP was examined using linear regression analysis with and without adjustment for age and sex. Special attention was given to the thresholds of 130/80 and 135/85 mmHg, the latter value being the recognized threshold for defining hypertension using awake ambulatory BP, home BP and AOBP in other guidelines. The mean adjusted AOBP of 130/80 and 135/85 mmHg corresponded to mean awake ambulatory BP values of 132.1/81.5 and 134.4/84.6 mmHg, respectively. These findings support the use of AOBP as the method of choice for determining office BP in routine clinical practice, regardless of which of the two thresholds are used for diagnosing hypertension, with an AOBP of 135/85 mmHg being somewhat closer to the corresponding value for awake ambulatory BP.