Gender-specific effect of outdoor temperature and seasonal variation on blood pressure components: a cross-sectional study on Iranian adults from 2015 to 2018.

Abstract

Blood pressure (BP) is influenced by both individual and environmental factors such as ambient temperature. However, the gender-stratified and component-specific impact of temperature on BP is not well understood. Herein, we examined the temperature and seasonal effects on four main BP components, namely systolic BP (SBP), diastolic BP (DBP), mean arterial pressure (MAP), and pulse pressure (PP), in both genders. A total of 8990 (3954 men) Tehranian adults during 2015-2018 were included. Linear regression models for analyzing data in three models including unadjusted, age-adjusted, and further adjusted for known sociodemographic and cardiovascular confounders were conducted. Among women, each 10°C increment was associated with a significant decrease of - 0.48mmHg (95% confidence interval (CI): - 0.86, - 0.19) and - 0.65mmHg (- 0.76, - 0.41) in SBP and MAP, respectively. In men, the corresponding value for SBP was - 0.46 (- 0.82, - 0.16) mmHg (P = 0.058). Gender-specific analysis in each season showed that among women, PP increased in autumn and winter with each 10°C decrease (P < 0.05). The mean increase in SBP (3.4 and 2.06mmHg in women and men, respectively), DBP (1.66 and 1.19mmHg), and MAP (2.71 and 1.12mmHg) was observed during winter compared to summer (all P < 0.05). PP showed seasonality only in women (1.46mmHg, P-value = 0.003). In both genders, SBP in age > 60years was more susceptible to variation compared to younger ages. Furthermore, obese women had more SBP changes compared to their non-obese counterparts (all P for interaction < 0.05). In conclusion, there was a sex difference in BP response to the outdoor temperature, with higher vulnerability among women. The reverse relation between temperature and BP occurred particularly among elderly and obese individuals. Careful monitoring of BP in cold seasons, specifically in the mentioned subgroups, could potentially attenuate cardiovascular risks.