We aimed to estimate the effects of indoor and outdoor temperature on wintertime blood pressure (BP) among peri-urban Beijing adults.
We enrolled 1279 adults (ages: 40–89 years) and conducted measurements in two winter campaigns in 2018–2019 and 2019–2020. Study staff traveled to participant homes to administer a questionnaire and measure brachial and central BP. Indoor temperature was measured in the 5 min prior to BP measurement. Outdoor temperature was estimated from regional meteorological stations. We used multivariable mixed-effects regression models to estimate the within-individual and between-individual effects of indoor and outdoor temperatures on BP.
Indoor and outdoor temperatures ranged from 0.0 to 28 °C and −14.3 to 6.4 °C, respectively. In adjusted models, a 1 °C increase in indoor temperature was associated with decreased SBP [−0.4 mmHg, 95% confidence interval (CI): −0.7 to −0.1 (between-individual; brachial and central BP); −0.5 mmHg, 95% CI: −0.8 to −0.2 (within-individual, brachial BP); −0.4 mmHg, 95% CI: −0.7 to −0.2 (within-individual, central BP)], DBP [−0.2 mmHg, 95% CI:−0.4 to −0.03 (between-individual); −0.3 mmHg, 95% CI: −0.5 to −0.04 (within-individual)], and within-individual pulse pressure [−0.2 mmHg, 95% CI: −0.4 to −0.04 (central); −0.3 mmHg, 95% CI: −0.4 to −0.1 (brachial)]. Between-individual SBP estimates were larger among participants with hypertension. There was no evidence of an effect of outdoor temperature on BP.
Our results support previous findings of inverse associations between indoor temperature and BP but contrast with prior evidence of an inverse relationship with outdoor temperature. Wintertime home heating may be a population-wide intervention strategy for high BP and cardiovascular disease in China.