Declining Prevalence of Tobacco Smoking in Vietnam
METHODS: This study included 14,706 participants (46.5% males, response proportion 64%) aged 25-64 years selected by multi-stage stratified cluster sampling. Smoking and socio-demographic measurements were made using the standardised procedures of the WHO STEPS methodology. Prevalence of smoking was estimated in reconstructed analyses with stratification by age, calendar year, and year of birth.
RESULTS: Prevalence of ever-smoking was 74.9% (men) and 2.6% (women). Male ever-smokers commenced smoking at median age of 19.0 (IQR 17.0, 21.0) years and smoked median quantities of 10.0 (IQR 7.0, 20.0) cigarettes/day, whereas female ever-smokers commenced smoking at median age of 20.0 (IQR 18.0, 26.0) years and smoked median quantities of 5.0 (IQR 4.0, 10.0) cigarettes/day. Prevalence has decreased in recent birth cohorts of men (p=0.001), and its inverse association with years of education (p<0.001) has strengthened for those born after 1969 (interaction p<0.001). Tobacco control initiatives in the 1990s coincided with changes in smoking prevalence (p=0.009). At 60 years of age, 53.0% of men were current smokers and they had accumulated median exposures of 39.0 (IQR 32.0, 42.0) years of smoking and 21.0 (IQR 11.5, 37.0) pack-years of cigarettes. The proportion of ever-smokers has decreased consistently among successive cohorts of women (p<0.001).
CONCLUSIONS: Smoking prevalence is declining in recent birth cohorts of men, and continues to decline in successive cohorts of women, possibly in response to anti-tobacco initiatives commencing in the 1990s. Low proportion of quitters means that Vietnamese smokers accumulate high exposures despite moderate quantities of cigarettes smoked per day.