Public release date: 5-Nov-2007

ORLANDO, Nov. 5 — Fewer people treated for high blood pressure return to normal pressure levels in the winter compared to those treated in the summer, Veterans Affairs (VA) researchers reported at the American Heart Association’s Scientific Sessions 2007.

The five-year study analyzed electronic health records from 15 VA hospitals in warmer and colder cities throughout the United States. Researchers identified 443,632 veterans with high blood pressure. Those who had readings of more than 140 mm Hg systolic or more than 90 mm Hg diastolic on three separate days were identified as hypertensive.

“The bottom line is that regardless of whether you’re in Anchorage, Alaska or San Juan, Puerto Rico, there is a difference in high blood pressure returning to normal in the winter compared to the summer,” said Ross D. Fletcher, M.D., the study’s lead author and chief of staff at the VA Medical Center in Washington, D.C.

The study found a significant variation in every city, warmer or colder, in return to normal blood pressure in winter compared to summer. The average significant difference in percent of patients returning to normal was 7.76 percent between the two seasons, based on patients’ blood pressure readings as recorded in their Electronic Health Record.

“San Juan is virtually equal to Anchorage, as blood pressure systematically worsens in the winter and improves in the summer,” Fletcher said. “We did not see the coldest city had the biggest change in blood pressure.”

He emphasized the importance of designing treatment strategies for patient’s high blood pressure to account for these seasonal variations, perhaps requiring increased anti-hypertensive intervention during the winter months.