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ObjectiveTo clarify the extent to which smokers in the general population experience tobacco withdrawal symptoms and whether such experience differs in those who continue to smoke and those who stopped smoking.MethodsWe included relevant questions in the nationally-representative China Health Literacy Survey (CHLS) conducted in 2018–2019. Among 87,028 participants, there were 22,115 ever-smokers aged 20–69 years who provided information on their smoking history and their experience of tobacco withdrawal symptoms. Multivariate logistic regressions were conducted to explore the association between withdrawal symptoms and other variables.ResultsAmong ever-smokers, there were 19,643 (88.8%) current smokers and 2,472 (11.2%) ex-smokers. Among current smokers, 61.3% reported having tried to quit smoking in the past. Overall, 61.1% of current smokers reported experiencing withdrawal symptoms: 69.9% of those who tried to quit smoking in the past and 47.5% of those who did not. A lower proportion of ex-smokers experienced withdrawal symptoms (46.3%) and the difference remained significant after controlling for demographic characteristics (OR = 1.76, 95% CI 1.62–1.93, P < 0.001). The most commonly reported withdrawal symptoms in both current smokers and ex-smokers were craving, restlessness and anxiety. In the multivariable-adjusted analyses, those who experienced withdrawal symptoms when they tried to quit smoking (OR: 2.05, 95% CI: 1.86–2.27) were less likely to successfully quit.ConclusionsThe clinical picture of the tobacco withdrawal syndrome is the same in current smokers and in ex-smokers, but ex-smokers are less likely to have experienced it. The experience of discomfort when unable to smoke is common and seems likely to be a major factor contributing to maintaining smoking behavior not just among individuals seeking help with quitting smoking, but among smokers generally.

Summary: Background: Tobacco dependence is the key barrier to successful smoking cessation. However, little is known about its prevalence, sociodemographic characteristics and determinants. We aimed to estimate the prevalence, associated factors and burden of tobacco dependence in China. Methods: During 2018–2019, the nationally representative 2018 China Health Literacy Survey (2018 CHLS) invited 87,708 participants to participate using a multistage stratified sampling method from 31 provinces (or equivalent) in mainland China, and 84,839 participants aged 20–69 with valid data were included in the analysis. We diagnosed tobacco dependence based on international criteria (ICD-10, DSM-4) and tailored to Chinese population according to China Clinical Guideline for Tobacco Cessation (2015 version). The prevalence of tobacco dependence was estimated overall and by sociodemographic factors. The Logistic regression was conducted to estimate odds ratios (OR) and 95% confidence intervals (CIs) for tobacco dependence and success of smoking cessation (being ex-smokers), with different levels of adjustment. These were used to estimate the total number of adults who were tobacco dependent in China. Findings: In China, the estimated prevalence of current smoking was 25.1%, significantly higher in men than in women (47.6% vs 1.9%). The prevalence of current smoking varied approximately 3-fold (12.9% to 37.9%) across 31 provinces of China. Among general population aged 20–69 years, the prevalence of tobacco dependence was 13.1% (95% CI:12.2–14.1). Among current smokers, the prevalence of tobacco dependence was 49.7% (46.5–52.9%), with no difference between men and women (49.7% vs 50.8%). The prevalence of tobacco dependence was associated significantly with smoking intensity, defined by pack-years (1.62 [1.54–1.70] per 10 pack-years), cigarettes smoked per day (2.01 [1.78, 2.27] per 10 cigarettes), and smoking starting age (0.93 [0.90, 0.97] per 5 years). Given smoking intensity, the prevalence of tobacco dependence also varied by age, gender, certain socioeconomic status and regions. Compared with those without tobacco dependence, ever smokers with tobacco dependence were less likely to be ex-smokers (2.88, 2.59–3.21). In China, 183.5 (170.4–197.4) million adults (177.5 million were men) were tobacco dependent in 2018. Interpretation: In China, tobacco dependence is highly prevalent, with approximately half of current smokers being addictive, highlighting the need for coordinated effort to improve awareness, diagnosis and treatment of tobacco dependence. Funding: Chinese Academy of Medical Sciences (CAMS) Initiative for Innovative Medicine (CAMS 2021-I2M-1-010), National Key R&D Program of China (grant no 2017YFC1309400), and National Natural Science Foundation of China (grant no 81720108001). Note: Chinese translation of abstract is available in appendix section.

Liver cancer and liver cirrhosis are common causes of death in China, where chronic lifelong hepatitis B infection is a major cause of both diseases. To help determine whether smoking is a cofactor for the development of liver cancer, we ascertained retrospectively the smoking habits of 36,000 adults who had died from liver cancer (cases) and 17,000 who had died from cirrhosis (controls) in 24 Chinese cities and 74 rural counties. Calculations of the smoker vs. nonsmoker risk ratios (RR) for liver cancer mortality were standardised for age and locality. Among adult men (aged 35+) there was a 36% excess risk of death from liver cancer among smokers (smoker vs. nonsmoker standardised risk ratio [RR] =1.36, with 95% confidence interval [CI] 1.29–1.43, 2p<0.00001; attributable fraction 18%). In the general male population this indicates absolute risks of death from liver cancer before age 70 of about 4% in smokers and 3% in nonsmokers (in the absence of other causes). Most liver cancer, however, occurs among the 10–12% of men with haematological evidence of chronic hepatitis B infection, so among them the corresponding risks would be about 33% in smokers and 25% in nonsmokers. The RR was approximately independent of age, was similar in urban and rural areas, was not significantly related to the age when smoking started but was significantly (p<0.001) greater for cigarette smokers than for smokers of other forms of tobacco. Among men who smoked only cigarettes, the RR was significantly (p<0.001 for trend) related to daily consumption, with a greater hazard among those who smoked 20/day (RR 1.50, 95% CI 1.39–1.62) than among those who smoked fewer (mean 10/day: RR=1.32, 95% CI 1.23–1.41). Smoking was also associated with a significant excess of liver cancer death in women (RR 1.17, 95% CI 1.06–1.29, 2p=0.003; attributable fraction 3%), but fewer women (17%) than men (62%) were smokers, and their cigarette consumption per smoker was lower. Among women who smoked only cigarettes, there was a significantly greater hazard among those who smoked at least 20/day (mean 22/day: RR=1.45, 95% CI 1.18–1.79) than among those who smoked fewer (mean 8/day: RR=1.09, 95% CI 0.94–1.25). These associations indicate that tobacco is currently responsible for about 50,000 liver cancer deaths each year in China, chiefly among men with chronic HBV infection. © 2003 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]