Cold Weather May Challenge Blood Pressure Control

Megan Brooks

September 12, 2023

Adults with hypertension may have a harder time keeping their blood pressure (BP) in check during the winter months, a new study suggests.

A review of electronic health records of more than 60,000 US adults being treated for hypertension found that on average, systolic BP rose by up to 1.7 mm Hg in the cold winter months compared with the hot summer months.

On a population level, BP control rates decreased by up to 5% during the cold winter months compared with control rates in the warm summer months.

"Some patients may benefit from increased pharmacological intervention to keep blood pressure controlled during the winter," Robert Barrett, with the American Medical Association (AMA), Greenville, South Carolina, told | Medscape Cardiology.

"Individuals with hypertension or values near the range of hypertension may benefit from periodic blood pressure monitoring and improvements in physical activity and nutritional patterns during winter months to offset adverse effects from seasonal blood pressure changes," Barrett added in a news release.

Barrett presented the study findings at the American Heart Association (AHA) Hypertension Scientific Sessions 2023 in Boston, Massachusetts.

Supportive Data

Barrett explained that seasonal variation in BP has been previously documented, and as part of the evaluation for the AMA MAP Hypertension program, he and colleagues were interested in the effect of this variation on population control rates under standard metrics (visits with BP < 140/90).

They analyzed data from 60,676 men and women (mean age 62 years) with hypertension from six health care organizations in the southeastern and midwestern United States that were participating in the quality improvement program.

During the roughly 5-year assessment period, none of the patients had changes in their antihypertensive medication, and all had at least one visit in each temperate season. The researchers estimated the seasonal effect on average systolic BP and BP control (defined as < 140/90 mm Hg).

Across a total of 453,787 visits, systolic BP during the winter averaged 0.47 mm Hg higher (95% CI, 0.364-0.573) than the yearly average, with a significantly lower odds ratio (OR) for BP control (OR, 0.92; 95% CI, 0.91-0.94), the researchers report.

In contrast, average systolic BP was 0.92 mm Hg lower during the summer, with a higher likelihood of BP control (OR ,1.10; 95% CI, 1.07-1.12).

"Seasonal variation in blood pressure has a substantial effect on hypertension control, often defined as blood pressure < 140/90," Barrett told | Medscape Cardiology.

"Patients with hypertension are less likely to have their blood pressure controlled during winter than summer months. If the blood pressure is very well controlled, for example to < 130/80, then seasonal variation will have little effect on control to < 140/90," Barrett noted.

"However, if blood pressure is not well controlled, then patients near the 140/90 level could benefit from monitoring their blood pressure regularly, closer medical follow-up, and avoiding decreased physical activity and increased weight toward year end,' he added.

Commenting on the study for the | Medscape Cardiology, Wanpen Vongpatanasin, MD, clinical chair for the conference, said that it's "well known that BP tends to lower during summer months and patients may be susceptible to dehydration and acute kidney injury when BP is too low, particularly when treated with certain medication such as diuretics."

On the flip side, "cold weather predisposes to vasoconstriction as our blood vessel constrict to maintain core temperature and it could be challenging to manage BP. That's why it is important for high BP patients to monitor home BP regularly," said Vongpatanasin, professor of internal medicine and director of the Hypertension Section, Cardiology Division, UT Southwestern Medical Center in Dallas, Texas.

The study had no commercial funding. Barrett and Vongpatanasin have no relevant disclosures.

American Heart Association (AHA) Hypertension Scientific Sessions 2023. Abstract 463. Presented September 9, 2023.

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