Heated tobacco product use in Hong Kong adults : use pattern, health effects and correlates with tobacco industry denormalisation beliefs and COVID-19

Abstract

Heated tobacco products (HTPs) are aggressively marketed with the claim of reduced harm despite insufficient evidence. Current regulations on HTPs vary by country. To inform HTP control, this thesis examined 1) awareness, ever use and perceptions of HTPs, and associated factors; 2) the levels of exhaled carbon monoxide (CO) and salvia cotinine in a real-life setting; 3) HTP use in relation to depressive and anxiety symptoms; 4) tobacco industry denormalisation (TID) beliefs in relation to HTP use and public support for banning HTPs; and 5) influence of COVID-19 on HTP and other tobacco use, in Hong Kong adults. A territory-wide survey was conducted on 5000 households (7101 participants) in 2019/20 and 1255 households (1849 participants) in 2020/21. Sociodemographic factors, depressive and anxiety symptoms, and TID beliefs were measured and assessed for associations with HTP outcomes using logistic/Poisson regression with robust standard errors. A hotspot survey was conducted at outdoor smoking hotspots in 2019/20 on 1299 tobacco users. Exhaled CO from the hotspot survey (n=780) and saliva cotinine from household and hotspot surveys (n=620) were measured, and their differences among users of different products were examined using the Kruskal-Wallis test. The differences in average daily consumption were examined using linear regression. In 2021, I conducted in-depth interviews with 95 tobacco users over the phone. Deductive and inductive methodologies were used to code transcriptions, and factors for changes in tobacco use amid the COVID-19 outbreak were nested in the social-ecological model. Over half of Hong Kong adults were aware of HTPs but only 0.7% had ever used them, with higher percentages in conventional cigarette (CC) and electronic cigarette (EC) users. Positive perceptions of HTPs were more common in current and former HTP users. CC users, regardless of other tobacco use, had a higher CO level than exclusive HTP users. Saliva cotinine levels were similar between HTP and CC users. Dual users of CCs and HTPs smoked fewer CCs than exclusive CC users, but consumed more tobacco in total. Depressive and anxiety symptoms were associated with current HTP use and dual use of HTPs and CCs. TID beliefs were inversely associated with ever HTP use in current cigarette non-users but positively associated with ever HTP use in current cigarette users. Support for banning HTPs was associated with TID beliefs both in current users and current non-users. The perceived odourlessness of HTPs increased consumption of HTPs indoors when living with family members. Limited access to HTPs was compensated by cigarette use amid the COVID-19 outbreak. In conclusion, HTP use was uncommon in Hong Kong but higher in CC and EC users. Dual users of CCs and HTPs consumed more tobacco in total and had higher depressive and anxiety symptoms than exclusive CC users. HTP users compensated by smoking cigarettes when HTPs were unavailable. Our findings support quitting of CC smokers instead of switching to or concurrent use of HTPs, and promoting TID to increase public support for banning HTPs. Better cessation services targeting HTP and cigarette use are needed to help quit all tobacco.