A pragmatic trial in the Rio de Janeiro subway to capture smokers for a quitline: methodological challenges and opportunities

According to the World Health Organization, smoking is an important cause of death worldwide. To encourage smoking cessation, persuasive messages can be used to raise smokers' risk perception. This article discusses challenges and solutions in designing a study to evaluate the effect of two different communication strategies ("gains from quitting" vs. "losses from continuing smoking") in encouraging calls to a quitline. The authors conducted an intervention study in two subway stations for 4 weeks, considering only 1 strategy per station. Large posters containing non-age-specific images and texts, on the basis of the theme"shortness of breath," were displayed on central dividing columns on the boarding platforms. Call rates from the selected stations, and respective rate ratios, overall and per study week, were calculated. Passengers who were smokers, exposed to the positive-content message, called on average 1.7 times more often than did those exposed to the negative-content message (p = .01). Moreover, call rate ratios did not decline over the 4 weeks of the study (p = .40). The effectiveness findings suggest that antismoking campaigns could use positive-content messages in order to recruit a larger smoker population. The proposed methodology can also be used to evaluate effectiveness of messages for "capturing" individuals with other health problems (e.g., alcohol abuse), thereby increasing its potential impact.