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

BackgroundDespite 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.MethodsWe 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.FindingsThe 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%).InterpretationIn 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.

Validity of COPD diagnoses reported through nationwide health insurance systems in the People&rsquo;s Republic of China

“…This observation is surprising since rural health care facilities in the People’s Republic of China are less well equipped (including poor access to spirometry testing). 6 It is possible that in rural areas COPD cases may present in more advanced stages of disease 2 and, hence, are more easily diagnosed. In addition, our results could have been biased toward the rural regions as only 15% of the total COPD cases were from urban regions, whereaŝ37% of the adjudicated cases were from the urban areas.…”

“… 1 In the People’s Republic of China, COPD is the third leading cause of mortality and morbidity after cerebrovascular and ischemic heart diseases, but the disease rates vary substantially between different regions. 2 Although the Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria for COPD, 3 an international endeavor designed to indicate best clinical practice, 4 has recently been adopted in the People’s Republic of China, adherence to GOLD guidelines may be suboptimal due to established patterns of clinical practice and unequal distribution of health resources in the People’s Republic of China. 4 For example, spirometry, now required to diagnose COPD, 3 is carried out in less than one-third of COPD cases in the People’s Republic of China and is rarely available in rural areas.…”

A phenome-wide association study of a lipoprotein-associated phospholipase A2loss-of-function variant in 90 000 Chinese adults

“…For all vascular outcomes, controls excluded individuals reporting a history of CHD, stroke or transient ischaemic attack at baseline, or incident MVE. Tertiary outcomes were diabetes and COPD, including both prevalent (previous history or screen-detected 22 , 23 ) and incident cases and incident chronic kidney disease, liver disease, inflammatory disease, cancer and non-vascular death. Controls excluded individuals reporting a history of that disease at baseline.…”

Differential Features of COPD in China

“…A large population-based survey found that only 6.5% of COPD patients were tested with spirometry 21 . A China Kadoorie Biobank report of 512,891 adults from 10 regions across China found that only 11.2% of diagnoses of airflow limitation made in the period 2004-08 were correct, based on spirometry findings 71 . The proportion of cases of airflow limitation that went undiagnosed was greater among women, younger individuals, those with lower household income, those with fewer chronic respiratory symptoms, and current regular smokers 71 .…”