The proportion of hypertensive patients with blood pressure control fell substantially in the United States during the COVID-19 pandemic, if the data from 24 health systems is representative of national trends.
The decline in blood pressure control corresponded with – and might be explained by – a parallel decline in follow-up visits for uncontrolled hypertension from the same data source, according to Alanna M. Chamberlain, PhD, associate professor of epidemiology in the division of quantitative health sciences, Mayo Clinic, Rochester, Minn.
If the data are representative, a wave of cardiovascular (CV) events might be coming.
The study, called BP Track, collated electronic medical data on almost 1.8 million patients with hypertension from 2017 through 2020. Up until the end of 2019 and prior to the pandemic, slightly less than 60% of these patients had blood pressure control, defined as less than 140/90 mm Hg.
While the pre-COVID control rates were already "suboptimal," a decline began almost immediately when the full force of the COVID-19 pandemic began in March of 2020, said Dr. Chamberlain in reporting the BP Track results at the American Heart Association scientific sessions.
When graphed from the start of the pandemic until the end of 2020, the proportion under control fell 7.2% to a level just above 50%. For the more rigorous target of less than 130/80 mm Hg, the proportion fell 4.6% over the same period of time, leaving only about 25% at that level of control.
Repeat Visits for BP Control Rebounded
The proportion of patients with a repeat office visit within 4 weeks of a diagnosis of uncontrolled hypertension fell even more steeply, reaching a nadir at about the middle of 2020, but it was followed by a partial recovery. The rate was 5% lower by the end of 2020, relative to the prepandemic rate (31.7% vs. 36.7%), but that was 5% higher than the nadir.
A similar phenomenon was observed with several other metrics. For example, there was a steep, immediate fall correlating with the onset of the pandemic in the proportion of patients who achieved at least a 10–mm Hg reduction or a BP under 140/90 mm Hg when treated for hypertension. Again, the nadir in this proportion was reached in about mid-2020 followed by a partial recovery. By the end of 2020, 5.9% fewer patients were achieving 10–mm Hg or better improvement in BP control when treated relative to the prepandemic level (23.8% vs. 29.7%), but this level was almost 10% higher than the nadir.
Data Based on Electronic Medical Records
The nearly 1.8 million patient records evaluated in the BP Track study were drawn from the 24 centers participating in the PCORnet Blood Pressure Control Laboratory Surveillance System. Nationally distributed, 18 of the 24 systems were academically affiliated.
When stratified by race, the proportion of Asians meeting the definition of BP control prior to the pandemic was about 5% higher than the overall average, and the proportion in Blacks was more than 5% lower. Whites had rates of blood pressure control very near the average. The relative declines in BP and the proportion of patients with uncontrolled blood pressure who had a repeat visit within 4 weeks during the pandemic were generally parallel across racial groups.
The implications of these data and the role of the COVID-19 pandemic on blood pressure control are "concerning," according to Adam Bress, PharmD, department of population health sciences, University of Utah, Salt Lake City.
Citing a study published in 2020 that suggested blood pressure control rates in the United States were already declining before the COVID-19 pandemic, he said the COVID-19 epidemic appears to be exacerbating an existing problem. He expressed particular concern for populations who already have low rates of control, such as African Americans.
"The impact of COVID-19 is likely to be disproportionately greater for underserved and minoritized patients," said Dr. Bress, who was the lead author of a recent article on this specific topic.
The implication of BP Track is that a wave of cardiovascular events will be coming if the data are nationally representative.
"A recent meta-analysis shows that each 5–mm Hg reduction in blood pressure is associated with age-related reductions in CV events," Dr. Bress said. For those 55 years of age or older, he said the risk reduction is about 10%. Given that the inverse is almost certainly true, he expects diminishing blood pressure control, whether COVID-19-related or not, to translate into increased CV events.
However, there is no guarantee that the BP Track data are representative of the U.S. population, cautioned Eugene Yang, MD, professor in the division of cardiology, University of Washington, Seattle. Even though a large group of patients was included, they were largely drawn from academic centers.
Nevertheless, Dr. Yang, who chairs the Hypertension Working Group of the AmericanCollege of Cardiology's Prevention of Cardiovascular Disease Council, acknowledged that the implications are "scary."
If the data are representative, "this type of reduction in blood pressure control would be expected to have a significant impact on morbidity and mortality, but we also have to think of all the variables that were not tracked and might add to risk," he said. He named such risk factors as weight gain, diminished exercise, and increased alcohol consumption, which have been cited by others as being exacerbated by the pandemic.
If these lead to more cardiovascular events on a population basis, the timing of these events would be expected to be age dependent.
"If you look at the patients included in this study, about 50% were 65 years of age or older. In a population like this you would expect to see an increase in events sooner rather than later," said Dr. Wang.
In other words, if the trial is representative, a wave of cardiovascular events might be seen in the most vulnerable patients "within the next few years," Dr. Yang speculated.