A working definition of white‐coat hypertension must include nocturnal blood pressure

Abstract

The term white-coat hypertension (WCH) refers to a condition characterized by an elevation of blood pressure (BP) in the office with normal ambulatory or home values. Previous studies have estimated a prevalence of this condition ranging from 15-20% to 40-50% of individuals with elevated office BP. A controversy currently exists on whether WCH is a benign phenomenon and how it should be best defined. Some studies suggest that patients with the condition have a risk of cardiovascular events similar to patients with normotension, whereas others document an increased rate of target organ damage and cardiovascular events. 1 In some patients, WCH may deteriorate to persistent hypertension in the future, leading to the risk of cardiovascular events as a long-term outcome. Individuals with high-normal BP, additional cardiovascular risk factors (eg, obesity, metabolic syndrome, advanced age, and impaired glucose tolerance), and organ damage may be particularly susceptible to a poor prognosis in the presence of WCH. According to two recent meta-analyses, WCH is associated with a slightly increased risk of cardiovascular events compared with normotension, although this risk is well below that seen in either persistent hypertension or masked hypertension. Briasoulis et al 2 analyzed 14 studies with 29 100 participants and showed that individuals with WCH had higher rates of cardiovascular disease morbidity and mortality but not significantly different all-cause mortality and stroke risk compared with patients with normotension. Huang et al 3 analyzed 23 cohorts of 20 445 untreated individuals, 11 cohorts of 8656 treated individuals, and a mixed population including both treated and untreated patients (12 cohorts, 21 336 individuals) and concluded that WCH is associated with long-term risk of cardiovascular disease and total mortality in untreated and mixed populations but not in treated patients. All of the studies included in these meta-analyses based categorization of WCH either on ambulatory or home BP. In case of ambulatory BP, the most common definition of WCH was based on daytime BP only, thus excluding nighttime BP. However, many people have normotension during waking hours and hypertension during night sleep, and may thus be mistakenly classified as having WCH. Yet, there are few data comparing the prevalence and consequences of using daytime (awake), full 24hour, rather than nighttime (sleep), periods to define WCH. In fact, heterogeneity among recommendations from the different guidelines exists and there is currently controversy on which period of the day is most suitable for defining WCH (Table 1). The article by Anstey et al, 11 published in the present issue of the Journal of Clinical Hypertension, may help yield further evidence to unravel the dispute. In their study, based on a relatively large sample of black individuals in the community-based prospective cohort Jackson Heart Study, the authors showed that the prevalence of WCH may substantially vary according to the periods of the 24 hours used for classif...

Usefulness of ambulatory blood pressure measurement for hypertension management in India: the India ABPM study

“…However, this difference in prevalence may not be directly related to the study population, but to the method of calculating the WCH and MH prevalences. In the present study, it was chosen to consider daytime, 24-h, and night-time average BPs all together, which leads to a lower prevalence of WCH and a higher prevalence of MH than when considering only the 24-h ABPM average alone as was used in the ABPM data registry [22]. Considering only 24-h ABPM average for the present study would have led to more comparable prevalences for WCH and MH of 20% and 13%, respectively.…”

“…However, using the average of 24-h ABPM also causes a risk to miss elevated nocturnal blood pressure, which is the most important cardiovascular risk predictor [23]. The average BP obtained from less frequent night-time measurements could be diluted by the (normal) average BP obtained from the higher number of daytime measurements, leading to a normal 24-h average BP [22]. Nevertheless, the prevalence of MH in the present study is relatively high as compared to other studies, which may be additionally explained by other factors such as the higher male prevalence and the fact that treated patients showed a higher prevalence of MH than untreated patients, which is in contradiction with earlier findings [18].…”

Long-Term Risk of Progression to Sustained Hypertension in White-Coat Hypertension with Normal Night-Time Blood Pressure Values

“…We have recently found [ 8 ] in a follow-up of 7.4 years that WCHT patients who were classified on the basis of normal 24 h, daytime, and NBP showed a CV prognosis not different from NT but better than true hypertensives. This suggests that normal levels of NBP should be included in its classification to avoid misdiagnosis of WCHT, as suggested by some authors [ 33 ]. In general, a better prognosis of WCHT should be expected when normal NBP values are included in the definition of WCHT since NBP is a stronger predictor of risk than daytime BP [ 25 ].…”

“…We hypothesised that an incomplete classification of individuals with WCHT may have contributed towards the conflicting data among the different studies. In fact, most of the related studies have used office BP (≥140/90 mm·Hg) and out-of-office BP (≤130–135/80–85 mm·Hg) thereby avoiding considering NBP values [ 6 , 27 – 30 ]. In other words, nocturnal BP, which has been related strongly to the CV prognosis [ 8 , 23 , 24 , 31 , 32 ] was not considered in the WCHT definition in most of the available evidence, and this may have conditioned the results.…”

“…From its recognition in 1987, until now, the clinical prognosis of WCHT remains uncertain. Early longitudinal studies suggested that WCHT would be an innocent entity proposing that WCHT carries a similar risk to normotension and significantly lower than sustained hypertension (SHT) [ 2 – 6 ] even after adjusting for age and cardiovascular (CV) risk factors [ 4 , 7 – 11 ]. In contrast, other studies and meta-analyses suggest that WCHT carries a higher risk of CV morbidity and mortality and place it as an intermediate risk entity between NT and SHT [ 8 , 10 , 12 – 19 ].…”