title: [Characteristics of non-symptomatic chronic obstructive pulmonary disease patients].
abstract: OBJECTIVE
  To evaluate the epidemiological characteristics of non-symptomatic chronic obstructive pulmonary disease (COPD) patients in a rural area in Beijing.
  
  
  METHODS
  The data of 1,624 people aged more than 40 in 5 villages in Yanqing county in Beijing were collected. Information of medical history and symptom were obtained, and physical examination and lung function test were performed.
  
  
  RESULTS
  The prevalence of COPD was 9.1% (148/1 624) in this area. In these 148 patients, 62 (42%) were non-symptomatic and 86 (58%) were symptomatic, the prevalence of non-symptomatic COPD being 3.8% (62/1 624). There was no statistical difference in the sex, age, occupation, marriage status, education level and smoking index between the symptomatic and the non-symptomatic groups (all P > 0.05). The forced expired volume in one second (FEV(1)) and FEV(1)% predicted were lower in the symptomatic group [(1.3 +/- 0.7) L, (61 +/- 23)%] than those in the non-symptomatic group [(1.5 +/- 0.6) L, (70 +/- 22)%; all P < 0.05].
  
  
  CONCLUSIONS
  The prevalence of COPD was high in this area with a high percentage of non-symptomatic patients. The COPD prevalence might be underestimated due to the symptom free patients.
authors.affiliation: Department of Respiratory Medicine, Peking University Third Hospital, Beijing 100083, China.
authors.forename: Wan-zhen
authors.initials: WZ
authors.lastname: Yao
authors.forename: Hong
authors.initials: H
authors.lastname: Zhu
authors.forename: Ning
authors.initials: N
authors.lastname: Shen
authors.forename: Xiang
authors.initials: X
authors.lastname: Han
authors.forename: Yan-jing
authors.initials: YJ
authors.lastname: Liang
authors.forename: Li-qiang
authors.initials: LQ
authors.lastname: Zhang
authors.forename: Yong-chang
authors.initials: YC
authors.lastname: Sun
authors.forename: Zhen-ting
authors.initials: ZT
authors.lastname: Hao
authors.forename: Ming-wu
authors.initials: MW
authors.lastname: Zhao
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002681:China / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology*; D012129:Respiratory Function Tests; D012424:Rural Population