title: Regional variations in the prevalence and misdiagnosis of air flow obstruction in China: baseline results from a prospective cohort of the China Kadoorie Biobank (CKB).
abstract: BACKGROUND
  Despite the great burden of chronic respiratory diseases in China, few large multicentre, spirometry-based studies have examined its prevalence, rate of underdiagnosis regionally or the relevance of socioeconomic and lifestyle factors.
  
  
  METHODS
  We analysed data from 512 891 adults in the China Kadoorie Biobank, recruited from 10 diverse regions of China during 2004-2008. Air flow obstruction (AFO) was defined by the lower limit of normal criteria based on spirometry-measured lung function. The prevalence of AFO was analysed by region, age, socioeconomic status, body mass index (BMI) and smoking history and compared with the prevalence of self-reported physician-diagnosed chronic bronchitis or emphysema (CB/E) and its symptoms.
  
  
  RESULTS
  The prevalence of AFO was 7.3% in men (range 2.5-18.2%) and 6.4% in women (1.5-18.5%). Higher prevalence of AFO was associated with older age (p<0.0001), lower income (p<0.0001), poor education (p<0.001), living in rural regions (p<0.001), those who started smoking before the age of 20 years (p<0.001) and low BMI (p<0.001). Compared with self-reported diagnosis of CB/E, 88.8% of AFO was underdiagnosed; underdiagnosis proportion was highest in 30-39-year olds (96.7%) compared with the 70+ age group (81.1%), in women (90.7%), in urban areas (89.4%), in people earning 5K-10 K ¥ monthly (90.3%) and in those with middle or high school education (92.6%).
  
  
  CONCLUSIONS
  In China, the burden of AFO based on spirometry was high and significantly greater than that estimated based on self-reported physician-diagnosed CB/E, especially in rural areas, reflecting major issues with diagnosis of AFO that will impact disease treatment and management.
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Om P
authors.initials: OP
authors.lastname: Kurmi
authors.affiliation: School of Public Health, Peking University Health Science Center , Beijing , People's Republic of China ; Chinese Academy of Medical Sciences, Dong Cheng District , Beijing , People's Republic of China.
authors.forename: Liming
authors.initials: L
authors.lastname: Li
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Margaret
authors.initials: M
authors.lastname: Smith
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Mareli
authors.initials: M
authors.lastname: Augustyn
authors.affiliation: China National Center for Food Safety Risk Assessment , Beijing , People's Republic of China.
authors.forename: Junshi
authors.initials: J
authors.lastname: Chen
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Rory
authors.initials: R
authors.lastname: Collins
authors.affiliation: School of Public Health, Peking University Health Science Center , Beijing , People's Republic of China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Tongxiang Center for Disease Control , Tongxiang, Zhejiang , People's Republic of China.
authors.forename: Yabin
authors.initials: Y
authors.lastname: Han
authors.affiliation: Liuzhou Center for Disease Control , Liuzhou, Guangxi , People's Republic of China.
authors.forename: Jingxin
authors.initials: J
authors.lastname: Qin
authors.affiliation: Suzhou Center for Disease Control , Suzhou, Jiangsu , People's Republic of China.
authors.forename: Guanqun
authors.initials: G
authors.lastname: Xu
authors.affiliation: Pengzhou Center for Disease Control , Pengzhou, Sichuan , People's Republic of China.
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.affiliation: School of Public Health, Peking University Health Science Center , Beijing , People's Republic of China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Bian
authors.affiliation: Henan Center for Disease Control , Zhengzhou, Henan , People's Republic of China.
authors.forename: Gang
authors.initials: G
authors.lastname: Zhou
authors.affiliation: Worldwide Epidemiology, GlaxoSmithKline R&D , Uxbridge , UK.
authors.forename: Kourtney
authors.initials: K
authors.lastname: Davis
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Richard
authors.initials: R
authors.lastname: Peto
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Zhenming
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Liming
authors.initials: L
authors.lastname: Li
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Zhengming
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Junshi
authors.initials: J
authors.lastname: Chen
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Rory
authors.initials: R
authors.lastname: Collins
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Richard
authors.initials: R
authors.lastname: Peto
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Zhengming
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Garry
authors.initials: G
authors.lastname: Lancaster
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Yang
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Alex
authors.initials: A
authors.lastname: Williams
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Margaret
authors.initials: M
authors.lastname: Smith
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Ling
authors.initials: L
authors.lastname: Yang
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Yumei
authors.initials: Y
authors.lastname: Chang
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Iona
authors.initials: I
authors.lastname: Millwood
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Yiping
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Sarah
authors.initials: S
authors.lastname: Lewington
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Sam
authors.initials: S
authors.lastname: Sansome
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Robin
authors.initials: R
authors.lastname: Walters
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Om
authors.initials: O
authors.lastname: Kurmi
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Yu
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Bian
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Can
authors.initials: C
authors.lastname: Hou
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Yunlong
authors.initials: Y
authors.lastname: Tan
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Xin
authors.initials: X
authors.lastname: Cai
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Huiyan
authors.initials: H
authors.lastname: Zhou
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Xuguan
authors.initials: X
authors.lastname: Chen
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Zengchang
authors.initials: Z
authors.lastname: Pang
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Shanpeng
authors.initials: S
authors.lastname: Li
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Shaojie
authors.initials: S
authors.lastname: Wang
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Silu
authors.initials: S
authors.lastname: Lv
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Zhonghou
authors.initials: Z
authors.lastname: Zhao
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Shumei
authors.initials: S
authors.lastname: Liu
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Pang
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Liqiu
authors.initials: L
authors.lastname: Yang
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Hui
authors.initials: H
authors.lastname: He
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Bo
authors.initials: B
authors.lastname: Yu
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Shanqing
authors.initials: S
authors.lastname: Wang
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Hongmei
authors.initials: H
authors.lastname: Wang
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Chunxing
authors.initials: C
authors.lastname: Chen
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Xiangyang
authors.initials: X
authors.lastname: Zheng
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Xiaoshu
authors.initials: X
authors.lastname: Hu
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Minghao
authors.initials: M
authors.lastname: Zhou
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Ming
authors.initials: M
authors.lastname: Wu
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Ran
authors.initials: R
authors.lastname: Tao
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Yeyuan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Yihe
authors.initials: Y
authors.lastname: Hu
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Liangcai
authors.initials: L
authors.lastname: Ma
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Renxian
authors.initials: R
authors.lastname: Zhou
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Zhenzhu
authors.initials: Z
authors.lastname: Tang
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Naying
authors.initials: N
authors.lastname: Chen
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Ying
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Mingqiang
authors.initials: M
authors.lastname: Li
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Zhigao
authors.initials: Z
authors.lastname: Gan
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Jinhuai
authors.initials: J
authors.lastname: Meng
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Jingxin
authors.initials: J
authors.lastname: Qin
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Xianping
authors.initials: X
authors.lastname: Wu
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Ningmei
authors.initials: N
authors.lastname: Zhang
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Guojin
authors.initials: G
authors.lastname: Luo
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Xiangsan
authors.initials: X
authors.lastname: Que
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Xiaofang
authors.initials: X
authors.lastname: Chen
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Pengfei
authors.initials: P
authors.lastname: Ge
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Xiaolan
authors.initials: X
authors.lastname: Ren
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Caixia
authors.initials: C
authors.lastname: Dong
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Enke
authors.initials: E
authors.lastname: Mao
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Zhongxiao
authors.initials: Z
authors.lastname: Li
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Gang
authors.initials: G
authors.lastname: Zhou
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Shixian
authors.initials: S
authors.lastname: Feng
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Yulian
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Tianyou
authors.initials: T
authors.lastname: He
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Li
authors.initials: L
authors.lastname: Jiang
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Huarong
authors.initials: H
authors.lastname: Sun
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Min
authors.initials: M
authors.lastname: Yu
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Danting
authors.initials: D
authors.lastname: Su
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Feng
authors.initials: F
authors.lastname: Lu
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Yijian
authors.initials: Y
authors.lastname: Qian
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Kunxiang
authors.initials: K
authors.lastname: Shi
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Yabin
authors.initials: Y
authors.lastname: Han
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Lingli
authors.initials: L
authors.lastname: Chen
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Guangchun
authors.initials: G
authors.lastname: Li
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Huilin
authors.initials: H
authors.lastname: Liu
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Li
authors.initials: L
authors.lastname: Yin
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Youping
authors.initials: Y
authors.lastname: Xiong
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Zhongwen
authors.initials: Z
authors.lastname: Tan
authors.affiliation: Nuffield Department of Population , University of Oxford , Oxford , UK.
authors.forename: Weifang
authors.initials: W
authors.lastname: Jia
keywords: COPD Epidemiology; Tobacco and the Lung