A Prospective Cohort Study On The Relationship Between Physical Activity And Cardiovascular Disease And All-cause Mortality In Chinese Adults

Background and objectiveCardiovascular disease(CVD)is the leading cause of mortality and disease burden globally and in China.Adherence to healthy lifestyle is an essential way to prevent CVD,and physical activity(PA)is an important contributor to lifestyle.Based on the PA intensity assessed by metabolic equivalent(MET),PA could be classified as sedentary behavior(SB,≤1.5 MET),light-intensity PA(1.6-2.9 MET),moderate-intensity PA(3.0-5.9 MET),and vigorous-intensity PA(≥6.0 MET).Current PA guidelines recommend at least 150 minutes per week(min/wk)of moderate-intensity PA or at least 75 min/wk of vigorous-intensity PA or an equivalent combination.Emerging prospective studies investigated the associations of meeting the recommended moderate-to-vigorous intensity physical activity(MVPA),long-term changes in MVPA,and SB with CVD risk.However,previous studies were mainly from western countries,whereas evidence was scarce in China.Due to the big differences in lifestyle patterns,epidemiology characteristics of CVD and its risk factors,and genetic background between western countries and China,the evidence from western countries should not be directly extended to China.In addition,the effects of reallocating time from SB to PA on incident CVD risk are unknown,and it remains inconsistent whether the association between SB and CVD risk is modified by MVPA.This prospective cohort study among Chinese adults aimed to explore the dose-response relationships of MVPA and SB with the risk of CVD incidence,CVD mortality,and all-cause mortality;estimate the effects of meeting the recommended MVPA level and long-term changes in MVPA on CVD incidence,CVD mortality,and all-cause mortality;and evaluate the health benefits of reallocating time from SB to light-intensity,moderate-intensity,and vigorous-intensity PA,as well as the interaction and joint effects of MVPA and SB.Subjects and methodsThis study incorporated data from three sub-cohorts in the Prediction for Atherosclerotic Cardiovascular Disease Risk in China(China-PAR)project,including China Multi-Center Collaborative Study of Cardiovascular Epidemiology(ChinaMUCA)1998,International Collaborative Study of Cardiovascular disease in Asia(InterASIA),and Community Intervention of Metabolic Syndrome in China&Chinese Family Health Study(CIMIC).The baseline survey for ChinaMUCA 1998,InterASIA,and CIMIC was conducted in 1998,2000-2001,and 2007-2008,respectively.ChinaMUCA 1998 and InterASIA had the first follow-up survey conducted in 2007-2008,and all three sub-cohorts were followed-up in 2012-2015.During each survey,information on demographic characteristics,medical history,and cardiovascular risk factors was derived through standardized questionnaire,physical examination,and laboratory tests.During the follow-up survey,information on disease and survival status was collected by interviewing study participants or their proxies,and checking hospital records and/or death certificates.The primary endpoints in this study were incident CVD cases,CVD deaths,and all-cause deaths.For all the three sub-cohorts,PA information was collected using questionnaire during each survey,and SB was first assessed during 2007-2008 examination.The MVPA volume of each participant was calculated based on MET value and duration of each activity.With participants classified according to the quartiles of PA volume(i.e.,0,0.1-24.0,24.1-48.0 and≥48.1 MET-h/d)or sedentary time,(i.e.,<5,5-<8,8-<10,≥10 h/d),we used Cox proportional hazards models stratified by cohort sources to estimate the associations of MVPA and SB with CVD incidence,CVD mortality,and all-cause mortality.We used restricted cubic spline(RCS)analyses to describe the dose-response relationships of MVPA volume and sedentary time with the risk of CVD incidence,CVD mortality,and all-cause mortality.To estimate the gained disease-free years and life expectancy associated with meeting recommended MVPA,we classified participants into two groups by the minimum of the recommended MVPA volume(equivalent to 10 MET-h/wk),used age as the underlying time-scale of the Cox proportional hazards models,and then calculated the difference between the areas under survival curves of the two groups.Using InterASIA and ChinaMUCA 1998 sub-cohorts,we obtained the long-term changes in MVPA,and examined the associations between long-term changes in MVPA and CVD incidence,CVD mortality,and all-cause mortality.Isotemporal substitution models were applied to estimate the per-hour effects of replacing SB with light-intensity,moderate-intensity,and vigorous-intensity PA.To assess the joint association and interaction effects of SB and MVPA,subjects were cross-classified into 8 groups according to the quartiles of sedentary time(i.e.,<5,5-<8,8-<10,and>10 h/d)and the recommended MVPA level(i.e.,<10 and≥10 MET-h/wk).Stratified analyses were used to assess whether the associations of MVPA and SB with the risk of CVD incidence,CVD mortality,and all-cause mortality were modified by selected characteristics.ResultsFor the analyses between MVPA and each endpoint,a total of 100,554 participants without history of CVD at baseline were included.During a median follow-up of 7.3 years,4692 incident CVD events,1915 CVD deaths,and 5461 all-cause deaths were observed.For the analyses between SB and each endpoint,the 2007-2008 survey served as the baseline,and a total of 93,110 adults free from CVD at baseline were included.During a median follow-up of 5.8 years,3799 CVD cases,1525 CVD deaths,and 4235 all-cause deaths were identified.After adjustment for age,sex,geographic region,urbanization,education level,family history of CVD,current smoking and drinking status,negative associations between MVPA volume and the risks of CVD incidence,CVD mortality,and all-cause mortality were observed(all P for trend<0.001).Compared with the 1st quartile group of MVPA volume,the hazard ratios(HRs)and 95%confidence intervals(CIs)of the CVD incidence,CVD mortality,and all-cause mortality for the 4th quartile group were 0.65(0.60-0.71),0.56(0.48-0.65),and 0.66(0.61-0.72),respectively.Multivariable-adjusted RCS analyses showed that MVPA volume was linearly associated with CVD incidence(P for overall<0.001,P for non-linear=0.357),and non-linearly associated with CVD mortality and all-cause mortality(CVD mortality:P for overall<0.001,P for non-linear=0.040;all-cause mortality:P for overall<0.001,P for non-linear<0.001).The risk of CVD mortality and all-cause mortality decreased rapidly until around 20 MET-h/d of MVPA volume,and then the decreasing trend was attenuated.Compared with physically inactive participants at baseline,the multivariable-adjusted HRs(95%CIs)for participants meeting recommended MVPA level were 0.76(0.72-0.81),0.67(0.61-0.74),and 0.73(0.67-0.77)for CVD incidence,CVD mortality,and all-cause mortality,respectively.Compared with physically inactive participants,those meeting recommended MVPA postponed incident CVD for 1.17 years and had a 1.48-year longer life expectancy at the index age of 40 years.Compared with individuals who were inactive at both the baseline and follow-up survey,those keeping active over the period of follow-up had a substantial lower risk of CVD incidence,CVD mortality,and all-cause mortality,with the corresponding HRs(95%CIs)of 0.61(0.46-0.81),0.59(0.35-0.98),and 0.76(0.58-1.00),respectively.The association between MVPA and incident CVD was more pronounced among women than men;the association between MVPA and CVD mortality was more pronounced among women,and participants without hypertension or dyslipidemia than their counterparts;and the association between MVPA and all-cause mortality was stronger among women,older people,diabetes patients,and those with high predicted CVD risk than their counterparts.After adjustment for age,sex,geographic region,urbanization,education level,family history of CVD,current smoking,drinking status and MVPA,positive associations between sedentary time and CVD incidence,mortality and all-cause mortality were observed(all P for trend<0.001).Relative to those with<5 h/d sedentary time,the multivariable-adjusted HRs(95%CIs)for those with>10 h/d sedentary time were 1.51(1.34-1.70),1.27(1.05-1.52),and 1.16(1.04-1.29)for CVD incidence,CVD mortality,and all-cause mortality,respectively.Multivariable-adjusted RCS analyses showed non-linear relationships between sedentary time and CVD incidence,CVD mortality,and all-cause mortality(all P for overall<0.001,and P for non-linear of 0.004.0.024,and<0.001,respectively),and the shapes of the dose-response relationship curves appeared to be similar,since the risks were relatively flat until 5 h/d of SB and then started to increase significantly.Among those who reported ≥5 h/d sedentary time,the per-hour substitution of SB with light-intensity,moderate-intensity,and vigorous-intensity PA significantly reduced incident CVD risk by 5%,6%,and 8%,CVD mortality risk by 6%,8%,and 11%,and all-cause mortality by 5%,7%,and 8%,respectively.The harmful impacts of SB on CVD incidence and all-cause mortality were stronger among women than men,and the association between SB and CVD mortality was not statistically significant among participants with hypertension.When participants were cross-classified by SB and MVPA level,relative to those reporting SB of<5 h/d and meeting the recommended MVPA level,those with SB of ≥10 h/d and not meeting the recommended MVPA had the highest risk of CVD incidence,CVD mortality,and all-cause mortality,with the corresponding HR(95%CI)of 2.03(1.80-2.28),2.08(1.72-2.51),and 1.65(1.48-1.84),respectively.No significant modification effects of MVPA on the relationships between SB and CVD incidence,CVD mortality,and all-cause mortality were identified,with the P for interaction of 0.079,0.699,and 0.054,respectively.ConclusionThe findings demonstrated that MVPA volume was negatively associated with the risk of CVD incidence,CVD mortality,and all-cause mortality among Chinese general adults.Meeting the recommended PA level was significantly related to a reduced risk of CVD incidence,CVD mortality,and all-cause mortality,and maintaining the recommended PA level provided further cardiovascular benefits.Sedentary time was associated with increased risk of CVD incidence,CVD mortality,and all-cause mortality,regardless of whether meeting the recommended MVPA volume or not.Among participants with>5 h/d SB,replacing SB with light-intensity PA could reduce the risk of CVD incidence,mortality and all-cause mortality,and substitution SB with moderate-intensity or vigorous-intensity PA might convey even greater benefits.Our results implicate that public health measures should encourage Chinese adults to meet and maintain the guideline recommended MVPA volume,meanwhile.SB should be limited,and be replaced with PA of any intensity.Our study provided Chinese evidence for the "sit less,ove more" preventive strategies.