Season and outdoor temperature in relation to detection and control of hypertension in a large rural Chinese population

Abstract

Background: In many Western populations, blood pressure varies moderately with season and outdoor temperature. Relatively little is known about effects of seasonal changes in blood pressure on the detection and control of hypertension in general populations, especially in low- and middle-income countries.Methods: We analysed cross-sectional data of 57 375 (42% men) participants aged 30–79 (mean 52.3) years who were enrolled during 2004–08, as part of the China Kadoorie Biobank, from a rural county in the south-east costal Zhejiang Province. Analyses related daily mean outdoor temperature, obtained from local Meteorological Bureau, to mean systolic (SBP) and diastolic blood pressure (DBP), rate of newly detected hypertension and, among those with self-reported physician-diagnosed hypertension, rate of adequate blood pressure control, using multiple linear and logistic regression models.Results: The overall mean blood pressure was 135.9 mmHg for SBP and 80.5 mmHg for DBP. Daily outdoor temperature ranged between −2.9 and 33.7°C, with July being the hottest month (mean 29.4°C) and January the coldest (mean 4.0°C). Comparing January (the coldest month) with July (the warmest), the differences in the adjusted SBP/DBP were 19.2/7.7 mmHg. Each 10°C lower ambient temperature was associated with 6.9/2.9 mmHg higher SBP/DBP,14.1% higher prevalence of newly detected hypertension and, among those with pre-diagnosed hypertension, 13.0% lower hypertension control rate.Conclusion: In rural China, lower outdoor temperature is strongly associated with higher mean blood pressure and hypertension prevalence as well as poorer hypertension control, and should be considered when conducting population-based hypertension surveys and providing treatment for hypertensive patients.

Seasonal Variation of Overall and Cardiovascular Mortality: A Study in 19 Countries from Different Geographic Locations

“…The effect of local temperature on seasonality has been shown in geographically limited studies [20], [21]. However, we did not consider this aspect in our analysis because mean temperature at national level would not be very informative in several countries such as Chile or the USA due to the large within-country variations.…”

Epidemiological Characteristics of Hypertension in the Elderly in Beijing, China

“…This study showed that the control rate did not improve in the younger group, there are several reasons, some younger patients are young is still at full time or part time work, and increased mental stress, which lead to poor blood pressure control; therefore, we should strengthen the health care education for this population, encourage them to change their life style, monitor their blood pressure, and support regular attendance at follow-ups. The control rate did not increase in the rural population, which may be due to the difference between the urban and rural living standards, which include the dietary habits, physical labor intensity, and mental pressure [ 26 , 27 ]. People in the rural areas may have a lower education level, lack of health care knowledge, and absence of self-health care consciousness, which can lead to a low control rate of blood pressure; therefore, we should pay attention to the prevention and control of hypertension in the rural population.…”

Socioeconomic Status Modifies the Seasonal Effect on Blood Pressure

“…A large number of studies have consistently observed winter peaks and summer troughs in blood pressure values, in clinical, 1 – 4 general, 5 – 7 and special populations such as children 8 and pregnant women. 9 , 10 …”