| Objectives1.To understand the cumulative incidence rate and incidence density of chronic obstructive pulmonary disease(COPD)among adults aged 40 years or older in certain regions of China.2.To explore the factors related to COPD incidence among adults aged 40 years or older in certain regions of China.3.To explore the changes and associated factors of pulmonary ventilation function among adults aged 40 years or older in certain regions of China.MethodsThis study is based on the COPD surveillance among Chinese adults conducted between 2014 and 2015.A total of 12 counties/districts in 9 provinces located in eastern,northern,central,southern and southwest regions were selected from the COPD surveillance for the follow-up.Data from the COPD surveillance were used as the baseline which included demographic characteristics,personal and family medical histories,respiratory symptoms,smoking,second-hand smoking exposure,indoor pollution fuel exposure and occupational exposure through questionnaire,height,weight,blood pressure,heart rate,and the pre-and post-bronchodilator pulmonary ventilation function.A follow-up study was conducted among the participants of the baseline survey between August and December in 2018.The incidence of COPD and the main indicators of pulmonary ventilation function were identified through questionnaires,physical examinations,and pre-and post-bronchodilator pulmonary ventilation function tests,and the collection of the causes of death.The factors associated with the incidence of COPD and those associated with the changes of the main indicators of pulmonary ventilation function were further explored.The non-COPD participants at baseline were included in the study on COPD incidence.The participants with qualified pulmonary ventilation function tests during the baseline were included in the study on the changes of pulmonary ventilation function.Frequency and percentage(%,95%CI)were used to describe the sociodemographic characteristics and the distributions of COPD related risk factors.The Rao-Scottχ2 was used to examine the differences in the percentages of various factors between participants who were followed up and those who were not followed up.The frequency and rate(%,95%CI)was used to describe the COPD incidence rate among participants with different characteristics.The univariate and multivariate cox proportional hazards regression models were constructed to compare the differences in COPD incidence among participants with different characteristics at the baseline.The mean(x)was used to describe the values of main pulmonary ventilation function indicators(FEV1、FVC、FEV1/FVC)at the baseline and follow-up,the variations of main pulmonary ventilation function indicators(△FEV1、△FVC、△FEV1/FVC)and average of change rate of main pulmonary ventilation function indicators during the follow-up.The T-test or F-test was used to compare the differences in the changes of the main indicators of pulmonary ventilation function between participants with different characteristics.A multiple linear regression model was used to explore the factors associated with the variations of pulmonary ventilation function during the follow-up among participants with different characteristics.ResultsA total of 3028 participants were included in the study on COPD incidence.Among them,48 participants had dead and 2980 participants had the qualified post-bronchodilators pulmonary ventilation function tests.A total of 3618 participants were included in the study of the change of pre-bronchodilator pulmonary ventilation function.A total of 3558 participants were included in the study of the change of post-bronchodilator pulmonary ventilation function.1.Incidence rate of COPDAmong participants who were included in the study of COPD incidence,there were 202 new onset COPD cases.The cumulative incidence rate of COPD was 6.67%(95%CI:5.82%～7.63%).The average follow-up time was 3.268 years,and the incidence density was 20.41/1000 person-years.The incidence rate of COPD among the high age group was higher than the low age group.The incidence rates were 3.33%(95%CI:2.38%～4.64%),5.95%(95%CI:4.60%～7.63%),10.53%(95%CI:8.48%～12.98%),and 14.36%(95%CI:9.76%～20.52%)among 40～49 years old group,50～59 years old group,60～69 years old group,and 70 or older years old group,respectively.The incidence rate among males was 10.21%(95%CI:8.66%～12.00%),which was higher than females.The incidence rate was 11.20%(95%CI:9.12%～13.66%)among current smokers,which was higher than non-smokers.The incidence rates of the participants who were exposed to biofuels and those who were exposed to two types of polluted fuels were 8.03%(95%CI:6.51%～9.86%)and 9.00%(95%CI:6.73%～11.91%)respectively,which were higher than those who were not exposed to polluted fuels.2.Associated factors of COPD incidenceThe risk of COPD incidence increased with age.The risk of COPD incidence in the participants aged 50～59 years,60～69 years and 70 years or older was 1.70 times(RR=1.70,95%CI:1.10～2.62,P=0.017),2.64 times(RR=2.64,95%Cl:1.73～4.03,P<0.001)and 3.49 times(RR = 3.49,95%CI:2.01～6.07,P<0.001)that of those aged 40～49 years,respectively.The risk of COPD incidence in males was 2.63 times(RR=2.63,95%CI:1.71～4.04,P<0.001)that of females.The incidence risk among urban participants was 1.63 times(RR=1.63,95%CI:1.19～2.24,P=0.002)that of rural participants.Compared with participants without the exposure to polluted fuels,the incidence risks of those were exposed to biofuels and those were exposed to two types of polluted fuels was 1.81(95%Cl:1.19～2.76,P=0.006)and 2.45(95%Cl:1.52～3.94,P<0.001),respectively.3.Changes of pulmonary ventilation function(1)Changes of FEV1Before bronchodilation,the mean value of FEV1 was 2.550L and 2.452L at baseline and follow-up,respectively.The mean change was-0.098L,and the average change rate was 0.089L/year.The difference in FEV1 between baseline and follow-up was statistically significant(P<0.001).Differences in the decline in FEV1 were statistically significant among participants with different ages,genders,places of residence(urban/rural),BMI,family history of respiratory diseases,smoking status,smoking amounts(package-years)and indoor pollution fuel exposure.Participants who had a higher FEV1/FVC(≥80%)or non-COPD participants had a greater decrease in FEV1 than those who had severe airflow limitation at baselineAfter bronchodilation,the mean value of FEV1 was 2.622L and 2.528L at baseline and follow-up,respectively.The mean change was-0.093L,and the average change rate was 0.089L/year.The difference in FEV1 between baseline and follow-up was statistically significant(P<0.001).The decline in FEV1 was statistically significant among participants with different ages,genders,residences(urban/rural),BMI,family history of respiratory disease,smoking status and smoking amounts(package-year).Participants who had a higher FEV1/FVC(≥80%)or non-COPD participants had a greater decrease in FEV1 than those who had severe airflow limitation at baseline(2)Changes of FVCBefore bronchodilation,the mean value of FVC was 3.400L and 3.271L at baseline and follow-up,respectively.The mean change was-0.129L and the average change rate was 0.114L/year between baseline and follow-up.The difference in FVC between baseline and follow-up was statistically significant(P<0.001).A statistically significant difference in the decline in FVC was seen among participant with different ages,genders,residences(urban/rural),smoking status and smoking amounts(packages-year).Participants with severe airflow limitation(FEV1/FVC<80%)or COPD patients had a greater decrease in FVC than those with mild airflow limitation at baseline.After bronchodilation,the mean value of FVC was 3.107L and 3.293L at baseline and follow-up,respectively.The mean change value was-0.114L,and the average change rate was 0.116L/year between baseline and follow-up.The difference in FVC between baseline and follow-up was statistically significant(P<0.001).A statistically significant difference in the decline in FVC was observed among participants with different ages,genders,residences(urban/rural),smoking status,smoking amounts(package-years)and occupational exposures.Participants with severe airflow limitation(FEV1/FVC<80%)or COPD patients had a greater decrease in FVC than those with mild airflow limitation at baseline(3)Change of FEV1/FVCBefore bronchodilation,the mean value of FEV1/FVC was 75.233L and 75.199L at baseline and follow-up,respectively.The mean change was-0.024L,and the average change rate was 1.487L/year between baseline and follow-up.The changes in the FEV1/FVC among participants with different BMI,smoking amounts(package-years),occupational exposures,indoor pollution fuel exposures,FEV1/FVC at baseline,and the status of COPD at baseline were statistically significantAfter bronchodilation,the mean value of FEV1/FVC was 77.293 at baseline and 77.125 at follow-up.The mean change was-0.168,and the average change rate was 1.454/year between baseline and follow-up.Changes in FEV1/FVC among participants with different residences(urban/rural),family history of respiratory disease,smoking amounts(package-years),occupational exposures,indoor polluted fuel exposures,FEV1/FVC and COPD status at baseline were statistically significant 4.Factors associated with the changes in pulmonary ventilation function(1)Factors associated with FEV1 changesBefore bronchodilation,the decrease of FEV1 in the group aged 60 years or above was greater than in the group aged 40～49.The decrease of FEV1 in the males was greater than in the females.The decrease of FEV1 in urban residents was lower than in rural residents.The decrease of FEV1 in participants with BMI≥28kg/m2 was lower than in participants with normal BMI.The decrease of FEV1 in former smokers was lower than in non-smokers.The decrease of FEV1 in baseline COPD patients was lower than in non-COPD participantsAfter bronchodilation,the decrease of FEV1 in the group aged 50～69 years was greater than in the group aged 40～49.The decrease of FEV1 in the males was greater than in the females.The decrease of FEV1 in baseline COPD patients was lower than in non-COPD participants(2)Factors associated with FVC changesBefore bronchodilation,the decrease of FVC in the group aged 60～69 years was greater than in the group aged 40～49.The decrease of FVC in the males was greater than in the females.The decrease of FVC in baseline COPD patients was greater than in non-COPD participants.The decrease of FVC in urban residents was lower than in rural residents.The decrease of FVC in former smokers was lower than in non-smokersAfter bronchodilation,the decrease of FVC in baseline COPD patients was greater than in non-COPD participants.The decrease of FVC in urban residents was lower than in rural residents(3)Factors associated with FEV1/FVC changesBefore bronchodilation,the participants resided in urban areas had a greater reduction in FEV1/FVC than those resided in the rural areas.The participants with BMI<18.5kg/m2 had a greater reduction in FEV1/FVC than those with normal BMI The participants who were exposed to biofuels had a greater decrease in FEV1/FVC than those without indoor polluted fuel exposure.After bronchodilation,males had a greater reduction in FEV1/FVC than females.Compared with the rural residents,urban residents had a greater reduction in FEV1/FVC.Compared with participants without exposure to indoor polluted fuels,participants who were exposed to two types of polluted fuels had a greater decrease in FEV1/FVC.Conclusion1.The cumulative incidence rate of COPD among Chinese adults aged 40 years or older was 6.67%,with an incidence density of 20.41/1000 person-years.The risk of COPD incidence increased was related to the elderly,the men,the urban participants and those who were exposed to indoor polluted fuels.Moreover,childhood severe respiratory infection was related to the increased in the risk of COPD incidence in male participants,while lower BMI(BMI<18.5kg/m2),and family history with respiratory disease was related to the increased in the risk of COPD incidence in female participants2.After an average of 3.268 years of follow-up,the pre-and post-bronchodilator FEV1,FVC decreased significantly,and the FEV1/FVC decreased not very significantly among Chinese adults aged 40 years or older3.Before and after bronchodilation,the decrease of FEV1 in the older age group was greater than in the group aged 40～49,and was greater in the males than in the females;the decrease of FVC in baseline COPD patients was greater than in non-COPD participants.Moreover,before bronchodilation,the decrease of FVC in the group aged 60～69 years was greater than in the group aged 40～49,and was greater in the males than in the females. |
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