The Effect Of Extreme High Temperature Events On Blood Pressure In Guangdong Province

BackgroundThe study intends to analyze the effects of extreme high temperature events(hot extremes and heat waves)on blood pressure(systolic blood pressure(SBP),diastolic blood pressure(DBP),pulse pressure(PP)and hypertension)from the surveys on nutrition and chronic diseases of residents in Guangdong Province.Stratified analysis of age,gender and body mass index were carried out to identify populations whose blood pressure is vulnerable to high temperature.MethodThis study is a cross-sectional study,and the population is derived from multiple monitoring projects,including the Residents’ Dietary Nutrition and Health Status Research in Guangdong Province in 2002,the Adult Chronic Disease Related Risk Factors and Urban Adolescent Health Risk Behavior Surveillance in Guangdong Provincial in 2004,2007,2010,2013,and the Monitoring of Chronic Diseases and Nutrition of Residents in Guangdong Province in 2015.This study focuses on the effect of high temperature events on blood pressure,and selects survey subjects from May,September and October during the warm season.The objects were selected over the age of 18,and exclude those with missing of age,gender,BP(SBP/DBP),residential address,smoking,drinking,education,marital status,and occupation,5805 objectives are analyzed0 at last.Matching the meteorological factors during the year ten years ago and the day when blood pressure of participant was measured.Defining the hot days,hot nights,compound hot extremes and heat wave events based on 85% of the daily highest temperature and daily lowest temperature in the previous ten years.The days with lower temperatures in May and October are excluded to eliminate the cold effects.The lag time of constructing the distributed lag nonlinear model is set to 0～3 days.The analysis population is divided into the total hypertensive patients,old patients of hypertension and new patients of hypertension.After adjusting the demographic factors,behavior factors and other meteorological factors,the influence of daily high temperature,compound heat events and heat wave on BP and its lag effect are explored.The variables of age,gender and body mass index were stratified to determine the population vulnerable to high temperature events.Result1.The relationship between daily maximum temperature and SBP is J-shaped,with an inflection point at about 30°C;it is U-shaped with PP,and its lowest temperature is about 28°C.2.Hot nights and compound hot extremes have a significant increase in the SBP and PP of hypertensive patients,old patients of hypertension and new patients of hypertension,increasing respectively by 1.61(95%CI:0.22,3.03)mm Hg,4.82(95%CI: 3.62,6.03)mm Hg and 7.00(95%CI:1.69,12.30)mm Hg,6.75(95%CI: 2.24,11.28)mm Hg for hypertensive patients,increasing by 1.77(95%CI: 0.26,3.28)mm Hg,4.59(95%CI:3.35,5.82)mm Hg and 9.10(95%CI: 3.15,15.05),7.23(95%CI: 2.37,12.09)mm Hg for old patients of hypertension,increasing respectively by1.54(95%CI: 0.24,2.83)mm Hg,4.87(95%CI: 3.72,6.02)mm Hg and7.95(95%CI: 3.06,12.84)mm Hg,6.50(95%CI: 2.17,10.82)mm Hg for new patients of hypertension.Compound hot extremes increases the risk of hypertension in exposed populations,which is 3.00(95%CI: 1.09,8.27)times that of non-exposed populations.Night hots reduced the DBP of hypertensive patients,old patients of hypertension and new patients of hypertension by 3.21(95%CI: 2.30,4.12)mm Hg,2.82(95%CI: 1.84,3.80)mm Hg and 3.34(95%CI: 2.44,4.24)mm Hg.Hot days had no effect on BP related indicators.The lag effect of the heat waves is 1 day,and heat waves increase the SBP of the hypertensive patients and old patients of hypertension by 2.46(95%CI: 0.04,4.88)mm Hg and 3.32(95%CI:0.57,6.07)mm Hg.Compared with the heat wave non-exposed people,the risk of hypertension in the heat wave exposed people increased by0.82(95%CI: 0.15,1.88)times.3.Variables of age,gender and body mass index have a modifying effect on the relationship between extreme high temperature events and blood pressure effects.The PP of young and middle-aged new patients of hypertension is more sensitive to compound hot extremes;the SBP of young and middle-aged hypertensive patients and new patients of hypertension is more sensitive to heat waves.Heat waves have a more significant effect on DBP of young and middle-aged old patients of hypertension and SBP of overweight old patients of hypertension.Conclusion1.Under high temperature exposure,the SBP and PP of the population increase with the increase of the daily maximum temperature.2.Compound hot extremes have a significant increase in SBP,PP,and the risk of hypertension in the population.3.The heat waves increase the SBP and risk of hypertension in the population.4.Variables of age,gender and body mass index have a modifying effect on the relationship between extreme high temperature events and BP.