Genetic and healthy lifestyle factors in relation to the incidence and prognosis of severe liver disease in the Chinese population.

BACKGROUND: Severe liver disease (SLD), including cirrhosis and liver cancer, constitutes a major disease burden in China. We aimed to examine the association of genetic and healthy lifestyle factors with the incidence and prognosis of SLD. METHODS: The study population included 504,009 participants from the prospective China Kadoorie Biobank aged 30-79 years. The individuals were from 10 diverse areas in China without a history of cancer or liver disease at baseline. Cox regression was used to estimate adjusted hazard ratios (HRs) for incident SLD and death after SLD diagnosis associated with healthy lifestyle factors (smoking, alcohol, physical activity, and central adiposity). Additionally, the contribution of genetic risk for hepatitis B virus (HBV, assessed by genetic variants in major histocompatibility complex, class II, DP/DQ [ HLA - DP / DQ ] genes) was also estimated. RESULTS: Compared with those with 0-1 healthy lifestyle factor, participants with 2, 3, and 4 factors had 12% (HR 0.88 [95% confidence interval [CI] 0.85, 0.92]), 26% (HR 0.74 [95%CI: 0.69, 0.79]), and 44% (HR 0.56 [95%CI: 0.48, 0.65]) lower risks of SLD, respectively. Inverse associations were observed among participants with both low and high genetic risks (HR per 1-point increase 0.83 [95%CI: 0.74, 0.94] and 0.91 [95%CI: 0.82, 1.02], respectively; Pinteraction = 0.51), although with a non-significant trend among those with a high genetic risk. Inverse associations were also observed between healthy lifestyle factors and liver biomarkers regardless of the genetic risk. Despite the limited power, healthy lifestyle factors were associated with a lower risk of death after incident SLD among participants with a low genetic risk (HR 0.59 [95%CI: 0.37, 0.96]). CONCLUSIONS: Lifestyle modification may be beneficial in terms of lowering the risk of SLD regardless of the genetic risk. Moreover, it is also important for improving the prognosis of SLD in individuals with a low genetic risk. Future studies are warranted to examine the impact of healthy lifestyles on SLD prognosis, particularly among individuals with a high genetic risk.

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).

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. FINDINGS: 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%). INTERPRETATION: 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.

Exhaled carbon monoxide and its associations with smoking, indoor household air pollution and chronic respiratory diseases among 512,000 Chinese adults.

BACKGROUND: Exhaled carbon monoxide (COex) level is positively associated with tobacco smoking and exposure to smoke from biomass/coal burning. Relatively little is known about its determinants in China despite the population having a high prevalence of smoking and use of biomass/coal. METHODS: The China Kadoorie Biobank includes 512,000 participants aged 30-79 years recruited from 10 diverse regions. We used linear regression and logistic regression methods to assess the associations of COex level with smoking, exposures to indoor household air pollution and prevalent chronic respiratory conditions among never smokers, both overall and by seasons, regions and smoking status. RESULTS: The overall COex level (ppm) was much higher in current smokers than in never smokers (men: 11.5 vs 3.7; women: 9.3 vs 3.2). Among current smokers, it was higher among those who smoked more and inhaled more deeply. Among never smokers, mean COex was positively associated with levels of exposures to passive smoking and to biomass/coal burning, especially in rural areas and during winter. The odds ratios (OR) and 95% confidence interval (CI) of air flow obstruction (FEV1/FVC ratio<0.7) for never smokers with COex at 7-14 and ≥14 ppm, compared with those having COex<7, were 1.38 (1.31-1.45) and 1.65 (1.52-1.80), respectively (Ptrend<0.001). Prevalence of other self-reported chronic respiratory conditions was also higher among people with elevated COex (P<0.05). CONCLUSION: In adult Chinese, COex can be used as a biomarker for assessing current smoking and overall exposure to indoor household air pollution in combination with questionnaires.