Investigation On Prevalence And Risk Factors Of Chronic Obstructive Pulmonary Disease In Anhui Province,China

Background Chronic obstructive pulmonary disease?COPD?is characterized by progressive airflow obstruction that is only partly reversible,and causes a worldwide public health problem.About 90%of deaths caused by COPD occurred in low-income and middle-income countries.In 2016,it was the fifth leading cause of death in China,the largest developing country.However,over the past decade,few studies had examined COPD prevalence based on post-bronchodilator test in China.A reliable survey of spirometry-defined COPD in China was conducted during 2002-2004 among 20245adults aged 40 years or older and it observed an overall prevalence of 8.2%.More recently,two nationwide estimations indicated that the prevalence of COPD among people aged 40 years or older increased rapidly to approximately 13.6%during2014-2015.Available evidence has indicated that COPD prevalence could substantially vary across different regions of China,possibly because of their different economic levels,diverse lifestyles,and various population aging patterns.The population of residents in Anhui Province of east China was approximately 60 million,and the proportion of people aged40 years or older was 44.2%according to the 2010 Population Census.Anhui province has undergone rapid economic development and significant changes in lifestyle in the past decades,and its people has seen a substantial increase in life expectancy.Moreover,the proportion of urban population of Anhui increased from 30.7%in 2002 to 50.5%in2015.Given the high prevalence of tobacco smoking in Chinese men and COPD is common but preventable disease,assessment of the current burden of COPD in Anhui Province is thus urgent for the development of region-specific public health policy and better allocation of health-care resources.However,a recent systematic review conducted by Fang et al.indicated that no data are available for COPD prevalence in general adults of Anhui.Whether smoking and other risk factors are important in determining the magnitude of prevalence also is uncertain.The present study attempted to fill this knowledge gap and provide the first estimate of the prevalence and risk factors of spirometry-defined COPD in Anhui.Objective To analyze the prevalence of chronic obstructive pulmonary disease?copd?and related risk factors among residents aged 40 years or above in anhui province.To provide scientific evidence for prevention and control of chronic obstructive pulmonary disease?copd?.To provide basic data for evaluating the effectiveness of relevant health policies and prevention and control programs.Methods A complex,multistage,and probability sampling method was used to enroll a representative sample of adults aged 40 years or older in Anhui Province.The first stage of sampling was stratified based on urbanization level?high vs low?.Within each stratum,at least two disease surveillance points were randomly selected with probability proportional to the population size of the stratum.A total of 5 disease surveillance points covering around 5%of the population in Anhui were selected.At each disease surveillance point,three townships/sub-districts were randomly chosen in the stage.Two villages/neighboring communities were then randomly selected within each township/sub-district.One group of villagers with at least 150 households was randomly chosen within each community/village.Finally,100 households within each group of villagers were randomly chosen,and one family member aged at least 40 years old was selected randomly from each household by a Kish selection table.All subjects who fulfilled above selection criteria were invited to attend an interview.Trained staff from local community clinics or health stations asked the participants questions based on a standardized questionnaire.Spirometry was then tested following recommendations by the American Thoracic Society.Prebronchodilator and post-bronchodilator forced expiratory volume in 1 s?FEV₁?,forced expiratory volume in 6 s?FEV₆?,peak expiratory flow?PEF?and forced vital capacity?FVC?were measured.These tests also included the modified Medical Research Council?mMRC?dyspnoea score and the Global Initiative for Chronic Obstructive Lung Disease?GOLD?2017ABCD assessment tool.The detailed information on these procedures?including definition of COPD-specific risk factors,full details of the spirometry method used,and a quality grade method for spirometry results?is described in the nationwide prevalence study.In current study,COPD was defined as a post-bronchodilator FEV1:FVC ratio less than70%based on 2017 GOLD guidelines.The degree of obstruction was classified according to GOLD staging criteria.We calculated predicted values of FEV1 for normal lung function and the lower limited normal?LLN?of FEV1:FVC based on a nationwide study of reference values?available for 40-81years in this study?for spirometry in the Chinese population.The LLN of Chinese reference values was used to define COPD in a sensitivity analysis.The standardized prevalence was estimated in the overall population and in several subgroups.The prevalence was calculated using weights to represent the adult population aged 40 years or older in Anhui.The weights were calculated based on the study sampling scheme and data from the 2010 Population Census in Anhui.These weights may account for several features of the study,including non-response,oversampling for several demographic differences between the sample and the total population of Anhui.Unweighted estimations were used for analyses of COPD severity in view of only COPD patients were included.The analysis used all participants for whom the variables of interest were available.We did not impute missing data in this study.The statistical significance of difference was assessed by the?2test.Multivariable logistic regression was used to investigate potential risk factors for COPD.The calculation method for population-attributable fraction?PAF?was described by Graubard et al.All statistical analyses were performed using Stata version 14.2?Stata Corp,College Station,TX,USA?.All statistical tests were 2-sided,and a P value less than 0.05 was considered statistically significant.Exact P values were provided when it was?0.001 in all conditions.Results A total of 2770 participants had reliable post-bronchodilator results and were included in the final analysis.The overall prevalence of COPD was 9.8%?95%CI:8.2,11.7?.Prevalence was higher in men?14.8%,95%CI:12.6,17.2?than it was in women?5.2%,95%CI:3.1,8.7?.Among adults with COPD,45.0%?95%CI:39.1,51.0?had moderate or severe disease?GOLD stage II-IV?,0.7%?95%CI:0.2,2.9?reported that they had a previous pulmonary function test,and only 0.4%?95%CI:0.1,2.6?knew their diagnosis of COPD.Risk factors for COPD included older age?OR 1.06,95%CI:1.04-1.08?,male sex?OR 2.01,95%CI:1.22,3.33?,current smoking status?OR 2.63,95%CI:1.86-3.73?,primary school or lower education?OR 1.61,95%CI:1.12-2.31?,family history of lung disease?OR1.50,95%CI:1.17-1.93?,and indoor exposure to coal for cooking or heating?OR 1.55,95%CI:1.11-2.15?.Conclusions In conclusion,our data indicated that COPD was prevalent in the adult population of Anhui Province,China.The frequency of subjects with COPD who had a previous respiratory function test or who were aware of their diagnosis of COPD were very low.Tobacco smoking and indoor air pollution?exposure to coal for cooking or heating?were major preventable risk factors for the disease in Anhui.Actions such as health promotion for prevention of COPD,early detection of COPD in high-risk individuals,individualizedtreatmentofCOPD,andenforcingappropriate region-specific policies are urgently needed to reduce COPD-related burden.