Low temperature raises hypertension prevalence, lowers control rate

A cold weather may elevate blood pressure (BP) among individuals, particularly among those with known hypertension, a China study has shown. Low temperature may increase hypertension prevalence and decrease control rate.

The authors collected meteorological and BP data from 31,351 participants (aged ≥18 years) in Guangdong Province from 2004 to 2015 to estimate the effects of temperature on BP and calculate temperature-adjusted hypertension prevalence and control rate.

Participants were divided based on the 2018 European Society Arterial Hypertension Guidelines, namely normotensive patients (n=23,046), known hypertensive patients (n=2,807), and newly detected hypertensive patients (n=5,498).

A generalized additive model was used to establish the nonlinear relationship between daily mean temperature and BP. Then, the linear effects of temperature on BP were calculated among populations with different hypertension status. Finally, the authors calculated the temperature-adjusted hypertension prevalence and control rate.

An inverse association was noted between temperature and BP. For every 1 °C increase in temperature, systolic BP reduction was 0.37 mm Hg (95 percent confidence interval [CI], –0.40 to –0.33) for normotensive patients, 0.21 mm Hg (95 percent CI, –0.32 to –0.10) for newly detected hypertensive patients, and 0.81 mm Hg (95 percent CI, –1.02 to –0.59) for known hypertensive patients; the corresponding reductions in diastolic BP were 0.19 mm Hg (95 percent CI, –0.21 to –0.16), 0.01 mm Hg (95 percent CI, –0.06 to 0.08), and 0.44 mm Hg (95 percent CI, –0.56 to –0.32).

The hypertensive prevalence rates were 32.5 percent at 5 °C, 29.7 percent at 10 °C, 27.7 percent at 15 °C, 26.0 percent at 20 °C, and 25.0 percent at 25 °C, while the control rates were 12.0 percent, 17.5 percent, 23.5 percent, 30.1 percent, and 37.1 percent, respectively.

“Our findings suggest that temperature should be considered in hypertension clinic management and epidemiological survey,” the authors said.