Effect of Graphic Warning Labels on Cigarette Packs on US Smokers’ Cognitions and Smoking Behavior After 3 Months

ImportanceThe US Food and Drug Administration's implementation of graphic warning labels (GWLs) on cigarette packs is under challenge in US courts.ObjectiveTo determine whether GWLs can affect US smokers' perceptions about their cigarettes or health consequences and changes in smoking behavior.Design, setting, and participantsThis study was a randomized clinical trial of the effect of a 3-month, real-world experience of cigarettes with GWL packaging. Community recruitment was done from September 2016 through December 2019 of daily smokers from San Diego, California, aged 21 to 65 years, who were not ready to quit. Participants were randomized to purchase and receive cigarettes in 1 of 3 pack designs: GWL, blank, or standard US pack. Data analysis was performed from July 2020 to February 2021.InterventionsThe study manufactured GWL cigarette packs (3 versions with Australian-licensed images) and packs devoid of marketing. For 3 months, participants purchased GWL, blank, or standard US pack cigarettes that were delivered to their home.Main outcomes and measuresSmoking-related cognitions and behavior were queried by daily and weekly interactive text messages. Smoking behavior was self-reported before and after the intervention by 96% of randomized participants and was biochemically validated on a subsample.ResultsThe study sample included 357 participants (195 women [54.6%]; mean [SD] age, 39.5 [11.9] years); 116 were randomized to the standard US pack group, 118 were randomized to the GWL pack group, and 125 were randomized to the blank pack group. Over the 3 months, participants who received the GWL packs had reduced positive perceptions of recent cigarettes smoked compared with participants who received the branded US pack (mean difference, -0.46 SD; 95% CI, -0.73 SD to -0.20 SD; P