LAUSR

Background IQOS is a heated tobacco product marketed as an alternative to combustible cigarette smoking. Little is known about cigarette smokers’ IQOS health risk perceptions and if these risk perceptions impact IQOS use and cigarette smoking behaviour. Methods Adult, daily, non-treatment-seeking cigarette smokers (n=27), naïve to IQOS, were recruited from Philadelphia, Pennsylvania, USA. Participants were introduced to IQOS and then completed measures of risk perceptions. Participants were given an IQOS 2.4 holder, charger and HeatSticks, and asked to switch completely from cigarettes to IQOS for 14 days. The effects of risk perceptions on changes in IQOS use, cigarettes per day (CPD), the substitution of IQOS for cigarettes and motivation to quit smoking were evaluated. Results Over the 14-day switch period, CPD significantly decreased (B=−0.18, 95% CI=−0.26 to –0.09, p<0.0001), IQOS use significantly increased (B=0.02, 95% CI=0.00 to 0.03, p=0.042), as did the percentage IQOS HeatSticks that replaced CPD (B=0.02, 95% CI=0.01 to 0.03, p=0.005). Participants who perceived IQOS as less risky than cigarettes used fewer IQOS HeatSticks per day. A lower percentage of IQOS HeatStick substitution for cigarettes was observed for participants with higher versus lower risk perceptions (B=−0.14, 95% CI=−0.28 to –0.01, p=0.042). Motivation to quit increased from a mean of 5.53 to 6.79 on the contemplation ladder from baseline to day 14 (B=1.26, 95% CI=0.54 to 1.97, p<0.001). Conclusions Smokers reduced their smoking rate and increased motivation to quit smoking while using IQOS. IQOS risk perceptions did not directly account for reductions in smoking, although they may contribute indirectly through increased IQOS use.