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Should screening for undiagnosed hypertension in young adults be instigated?

Undiagnosed hypertension appears to be present in a large number of young men and who seem to be otherwise healthy. Rod Tucker explores the evidence and discusses how screening young adults for the condition could have a big impact on patient care.

Globally, hypertension is the main cause of cardiovascular disease and leading cause of early death. Moreover, there are several recognised risk factors for the disease and modification of these can reduce the risk of developing hypertension. But to what extent does the condition remain undiagnosed and what specific factors contribute to this under-diagnosis?

This was a question posed in a recent report by the UK’s Office for National statistics (ONS). The team used data from a sample of 21,476 adults and examined both the prevalence of the condition and the degree to which it was undiagnosed. The report estimated that hypertension (defined as blood pressure greater than 140/90mmHg) affected approximately 32% of adults living in private households in England. An additional finding was the condition remained undetected in 29% of cases, which equates to some 4.2 million adults across England.

But perhaps of greater concern, was that hypertension was less likely to be diagnosed among younger adults, largely because, as a group, such individuals are generally perceived as having better health. The ONS analysis suggested that undiagnosed hypertension was present in 66% of men and 26% of women, aged 16-24.

To put this into perspective, the ONS estimated that only 17% of men and 21% of women aged 75 years and over – where hypertension is much more common – had undiagnosed disease. Although younger men were were proportionately more likely to be undiagnosed than older adults, the highest total estimated number of cases of unrecognised hypertension was seen in males aged 55-64 years (500,000 cases) and females aged 65-74 years (460,000 cases).

Risk factors for undiagnosed hypertension

But were there any specific factors or reasons to account for undiagnosed disease? In a further analysis, the ONS identified, for instance, hypertension was more prevalent when an individual self-reported their general health as ‘very good or good’ (males 41%, females 28%) compared with ‘bad or very bad’ (males 18%, females 14%). Interestingly, while being overweight or obese are recognised risk factors for the condition, undetected disease was actually more likely in men who were not overweight or obese (44%) compared with obese individuals (30%). Additional factors included those who had never smoked (36%) and if they lived in a rural (42%) as opposed to an urban location (32%).

What are the implications of these findings?

The authors of the report propose that their data provides valuable insight for health services to help improve outcomes. Yet, this immediately raises a problem for healthcare providers in that the current risk stratification process for hypertension screening is predicated on the fact that the disease has a lower prevalence in younger adults. For example, one US study of 21,581 individuals found that a normal blood pressure was observed in 57.8% of those aged 18-44.

In other work by the CDC in the US, hypertension was identified in just over a fifth (22.4%) of those aged 18-39. Consequently, younger adults are likely to be excluded from hypertension services. In fact, the recently introduced NHS community pharmacy blood pressure check service in the UK is designed to ‘identify people over the age of 40 who have previously not been diagnosed with hypertension’.

Is it right to exclude younger people from hypertension screening? While levels of hypertension are generally lower in the younger age group, this is confounded to some extent by the current obesity epidemic. For instance, it has been suggested that approximately 30% of obese adolescents have hypertension. Furthermore, other estimates are that one in eight adults aged between 20 and 40 years have hypertension and that it is associated with abnormalities on heart and brain imaging, increasing the likelihood of cardiovascular events by middle age. Nevertheless, despite these risks, there is currently a paucity of randomised trial data demonstrating a health benefit from blood pressure lowering in this patient group.

But if there is one important take-home message from the ONS report, it is that the current risk stratification for hypertension screening requires modification and should not be age-restricted. Screening young people, especially if they are either overweight or obese, would enable an assessment of end-organ damage in those with even mildly elevated blood pressure. This revised strategy would allow clinicians to provide relevant lifestyle advice and to instigate therapy where this fails. Such an approach would inevitably help to identify and improve outcomes for those with undiagnosed hypertension.

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