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Trends in resistant hypertension
Researchers reveal the most up-to-date figures of the numbers living with resistant hypertension, an important risk factor for heart disease and stroke
In a popular presentation at the recent British and Irish Hypertension Society meeting in Glasgow, researchers painted an up-to-date picture of the trends in resistant hypertension over the last 20 years. The numbers highlight how common the problem is, and give clues on how it can be addressed.
What is resistant hypertension?
Resistant hypertension is blood pressure that remains above 140/90mmHg despite being treated with optimal doses of three or more antihypertensive drugs, including a diuretic.
Resistant hypertension is an important problem to address because it is associated with a 50% higher risk of a cardiovascular event, such as a heart attack or stroke, compared to “standard” hypertension.
Why was the research done?
Until now, we haven’t had accurate figures of how many people have resistant hypertension. Previous research is either out of date, hasn’t addressed adherence - whether or not people are taking the drugs as prescribed – or has been derived from clinical trials which have highly selected populations enrolled and don’t represent the general population.
How was the study done?
The team used electronic health records form primary care for more than 1.3 million people from 1995 - 2015 to find out how many people develop resistant hypertension each year and how many are living with it each year. Importantly, they tried to account for adherence using data on how often the medications were prescribed.
What did they find?
There was a steep rise in the number of people living with resistant hypertension between 1995 and around 2006, when it levelled off then started to fall. At its peak, 7.8% of people taking medications to lower their blood pressure had resistant hypertension, falling to 6.5% in 2015.
In terms of the number of people who newly developed resistant hypertension each year, there was a rise in the late 90s, peaking in the early 2000s, then started to decline after 2004.
What do the findings mean?
The steep rise in the numbers of people newly developing resistant hypertension between the late 1990s and early 2000s was probably due to greater detection and the use of more drugs to control high blood pressures. It was around this time that a number of important studies about hypertension were published, along with evidence suggesting that high blood pressure needs to be treated more aggressively.
After 2004, the proportion of people newly developing resistant hypertension decreased. The drop in numbers could possibly be due to 2004’s Quality and Outcomes Framework. This programme incentivised primary care practices to increase the proportion of their patients with controlled high blood pressure, and this might have helped to lower the numbers with resistant hypertension (which is typically uncontrolled high blood pressure).
Why these new figures are useful
Dr Sarah-Jo Sinnott, who led this research, is Assistant Professor at the London School of Hygiene & Tropical Medicine and has a special interest in drug treatments for resistant hypertension. She explains:
At 6.5% of people with treated hypertension, resistant hypertension is fairly common, and it’s an important risk factor for heart disease and stroke.
The rise and fall in the numbers is probably not due to any changes in physiology, but perhaps because of changes in the detection and treatment of high blood pressure over time. Interventions to lower the numbers with resistant hypertension would be best focused on adherence to blood pressure medications.