More home and office BP monitoring needed to catch hidden hypertension
More home blood pressure (BP) and office BP measurements should be encouraged to identify otherwise hidden cases of hypertension, says an expert.
According to Dr Azani Mohamed Daud, consultant cardiologist, patients with “white coat” or “masked” hypertension could be identified if both sets of measurements were conducted as standard practice, particularly with patients with other associated risk factors for cardiovascular disease (CVD).
“I can’t overemphasize this enough; we really need to be checking our patients’ BP, no matter the reason that they come to see us for in primary care,” said Azani. “We know that in Malaysia we only seem to be diagnosing 40% of hypertensives; that’s consistent every year (according to NHMS data). That’s as good as we’re getting at the moment. We need to do better.”
Speaking at the Malaysian Society of Hypertension 16th Annual Congress, Azani noted that the UK’s National Institute for Health and Clinical Excellence (NICE) 2011 guidelines established true sustained hypertension as a clinical BP of ⩾140/90 mmHg and a home BP average of ⩾135/85 mmHg. However, he added that there are individuals who do not necessarily have a sustained normotensive or hypertensive status.
White coat hypertension (WCH) refers to persistently elevated office BP measurements (⩾140/90 mmHg) with normal BP levels out-of-office (<135/85 mmHg). While not to be confused with the “white coat effect” (transient office BP elevation caused by an alerting reaction, normally eliminated by multiple spaced-out measurements), WCH is thought to be prevalent in 12% to 20% of hypertensives, and more common in the elderly. [Blood Press Monit 2005;10:311–316; Eur Heart J 1995;16:692–697]
On the other hand, masked hypertension (MH) is where a patient’s office BP may be <140/90 mmHg, but their out-of-office BP is found to be ⩾135/85 mmHg. This may be tied to particular times of day; daytime MH may be due to lifestyle stresses (occupational stress, smoking, alcohol consumption or poor exercise tolerance), while nocturnal MH may be due to sleep deprivation or other diseases such as obstructive sleep apnoea, metabolic syndrome, diabetes or chronic kidney disease (CKD).
Among patients already receiving treatment for hypertension, masked uncontrolled hypertension (MUCH) may be present and require further treatment optimization. However, home and office BP monitoring may not be sufficient to identify such patients; a Spanish study of 14,840 adults with apparently controlled BP found that in reality, 31% had MUCH which was only uncovered via ambulatory blood pressure monitoring (ABPM). [Eur Heart J 2014;35(46):3304–3312]
Despite WCH and MH not being classified as “true” hypertension, Azani warned that individuals with either condition still appeared to be at increased long-term CVD risk compared to normotensives. At a 10-year follow-up of 2,071 participants in the PAMELA* study, 18.2% of those who were initially normotensive had gone on to develop sustained hypertension. In contrast, 42.6% of those with WCH and 47.1% of those with MH had developed sustained hypertension in the same period. [Hypertension 2009;54:226–232]
“This group should not be neglected,” said Azani. “Even though the 2015 NHMS showed a slight overall dip in hypertension prevalence, there remain more people unaware than aware of their high BP status, based on office BP studies alone.”