Prevalence And Risk Factors Of COPD Among Non-smokers Over 40 Years In Selected Areas Of Liaoning Province

Objectives:Chronic obstructive pulmonary disease(COPD)is a disease characterized by progressive airflow obstruction and respiratory symptom.Nowadays the prevalence of COPD in China and the world is still significant,and different regions have different level of prevalence.COPD now had caused a terrible impact on our society.According to many researches,COPD can be caused by smoking,environmental pollution,biomass fuel pollution,occupational pollution exposure,gender and age,the level of education and income,and other more risk factors.Among them,smoking is the most influential factor and the most important factor in most studies.While smokers constitute a small percentage of the population,more people do not smoke.And there are few researches conducted among non-smokers.The study which caused on non-smokers is still necessary because studies among non-smokers can help us to explore the role of other risk factors besides smoking,and will be helpful for the further study of COPD.According to some survey,the prevention of COPD in most regions still lacks a perfect organizational plan,and our survey in Liaoning Province can also provide some data support for the establishment of strategies.Our research mean to obtain the prevalence of COPD among non-smokers in selected areas of Liaoning Province,Northeast China,and to estimate risk factors of COPD,so that we can provide some data support for similar researches.Methods:Our research used a multistage random cluster sampling method and collected 2397 valid information.we conducted face-to-face questionnaire,lung function tests and physical examinations,then counted the information of non-smokers.Non-smokers were the subjects of this study.With FEV1/FVC<70%after inhaling bronchodilator as the diagnostic standard,we determined the characteristics of persistent airflow limitation of respondents,and excluded other known cardiopulmonary diseases by chest X-ray and ELECTRO cardiogram,then diagnosed respondents as COPD.We used a method of complex sampling weighting adjustment to calculate the prevalence of COPD and used the univariate and multivariate logistic regression to estimate risk factors of COPD(P<0.05 was considered statistically significant).Results:This research recruited 1369 non-smokers aged 40 years and older,among them 226 were COPD patients,and the prevalence of COPD was 17.92%(95%CI:16.68～19.16%).Among our survey,735(53.69%)of subjects were the urban population and 634(46.31%)of subjects were the rural population.The prevalence rate of rural population(21.24%,95%CI:19.93%～22.56%)was significantly higher than that of urban population(11.55%,95%CI:6.99%～16.12%),the difference was statistically significant(χ2=40.27,P<0.05),and the difference was also presented in the two genders.There were 299 males(21.84%)and 1070 females(78.16%)in our survey,females were the most important part of this population.The prevalence in females(18.40%,95%CI:15.60%～21.20%)was slightly higher than that in males(16.32%,95%CI:3.16%～29.48%),but chi-square test showed no significant difference.Exposed to biomass fuel combustion products had a significant impact on the prevalence of COPD(x 2=141.3047,P<0.05).Exposure to harmful occupational pollutants also significantly affected the prevalence of COPD(x2=100.2303,P<0.05).There is a close cross of combined effects between biomass fuel combustion exposure and occupational harmful factors exposure,the exposure rate of overlap area was 22.94%,the two kinds of risk factors and other risk factors(secondhand smoke exposure,family history and childhood severe respiratory infection)had the same exposure situation.The combined effect of multiple risk factors can lead to an increase in the prevalence of COPD.The univariate logistic regression showed that living in the rural area,advanced age,low educational level,low income level,household biomass pollution exposure and occupational pollution exposure were associated with the increased risk of COPD among non-smokers.The multivariate logistic regression showed that age(OR:4.235,95%CI:2.876～6.235),educational level(OR:1.903,95%CI:1.460～2.480),income level(OR:1.493,95%CI:1.394～1.600),household biomass pollution exposure(OR:1.431,95%CI:1.220～1.679)and occupational pollution exposure(OR:1.414,95%CI:1.143～1.749)were risk factors of COPD.Conclusion:In selected areas of Liaoning Province,COPD is highly prevalent among non-smokers.And correlative major risk factors included advanced age,low educational level,low income level,household biomass pollution exposure and occupational pollution exposure(P<0.05).The coordinated exposure of multiple risk factors may be the main reason leading to the increase in the prevalence of COPD.