Association between heated tobacco product use and airway obstruction: a single-centre observational study, Japan

Background While heated tobacco products (HTPs) may affect pulmonary function, the evidence supporting the utility of screening for HTP use in clinical settings is insufficient. We examined the association between HTP use and airway obstruction after switching from cigarettes. Method The study subjects were patients aged >= 20 years undergoing surgery from December 2021 to September 2022 who completed spirometry and reported tobacco (cigarette and HTP) use status during the preoperative assessment. Airway obstruction was defined as forced expiratory volume in 1 s to forced vital capacity ratio below the lower limit of normal. Current tobacco use was defined as past-30-day use. Multivariable Poisson regression analysis was performed to examine the associations between HTP use and airway obstruction by adjusting for demographic characteristics, lifetime cigarette smoking (pack-year) and duration of smoking cessation. Results Overall (N=2850, 55.4% women, mean age 62.4), 4.6% and 10.7% reported current HTP use and cigarette smoking, respectively. 16.8% had airway obstruction. Airway obstruction was more common among current HTP-only users (adjusted prevalence ratio (APR)=2.32), current cigarette-only smokers (APR=2.57) and current dual users (APR=2.82) than never-tobacco users. Among current tobacco users (N=398), the prevalence of airway obstruction was not significantly different between HTP-only users and cigarette-only smokers. Among former cigarette smokers (>30-day cigarette quitters) (N=1077), current HTP users had 1.42 times the increased prevalence of airway obstruction than never-HTP users after adjusting for cigarette pack-year; a stronger association was observed when the analysis was restricted to >= 5-year cigarette quitters (N=772) (APR=1.96, vs never HTP users). Conclusion Current HTP use was associated with airway obstruction among patients with cancer who had completely switched from cigarettes even after quitting smoking for a long period. Patients should be routinely screened for HTP use and advised to quit any tobacco.