摘要：Objectives. We assessed the effects of levels and duration of exposure to televised antismoking advertising on cognitive and behavioral changes. Methods. We used data from a serial cross-sectional telephone survey with weekly interviews of adult smokers and recent quitters in New South Wales, Australia (n = 13 301), between April 2005 and December 2010. We merged survey data with commercial TV ratings data to estimate individuals’ exposure to antismoking advertising. Results. Logistic regression analyses indicated that after adjustment for a wide range of potential confounders, exposure to antismoking advertising at levels between 100 and 200 gross rating points per week on average over 6 to 9 weeks was associated with an increased likelihood of having (1) salient quitting thoughts and (2) recent quit attempts. Associations between exposure for shorter periods and these outcomes were not significant. Conclusions. Broadcasting schedules may affect the success of antismoking ads. Campaign planners should ensure advertising exposure at adequate frequency over relatively sustained periods to maximize impact. In the Australian state of New South Wales, adult smoking prevalence declined from 20.1% in 2005 to 15.8% in 2010, 1 during a period of implementation of tax increases on tobacco products, graphic health warnings on packs, clean indoor air legislation, and point-of-sale display bans. In addition, the government has made significant investments in televised antismoking mass media campaigns. Studies that merge commercial TV ratings data at the market level with individual-level data have demonstrated that increases in an individual’s potential exposure to televised antismoking campaigns are associated with improved youth smoking-related attitudes, beliefs, and behaviors 2–6 ; increased calls to quitlines 7–13 ; increased quitting behaviors among adults 14–16 ; and decreased adult smoking prevalence. 17 It is increasingly recognized that the response of smokers to mass media campaigns is likely to be influenced by the kinds of messages broadcast. 11,13,15 The extent of population exposure to those messages is also an important factor in determining the impact of media campaigns. 16 Identifying the level and duration of campaign media placement to achieve optimum population response is a critical question of efficiency for campaign planners and funders. Despite a consensus that advertising must reach the audience a sufficient number of times to be effective, 18–20 attempts to quantify the advertising intensity that can most efficiently influence behavior have not yet resulted in firm conclusions. Among adult smokers, one estimate suggested that for every 2 exposures to anti-tobacco advertisements per month, the quit rate increased by approximately 10%. 14 A more recent study showed that the likelihood of quitting within a 2-year period increased 49% with an additional 2 exposures per month. 15 Less attention has been paid to how population response to antismoking advertising builds and decays. Although some advertisements may be recalled long after the end of a campaign, campaign effects on the most critical outcome of behavioral response are detectable only while they are being broadcast or for a short time after. 17,21,22 Although public health researchers have started to address the issue of advertising decay, studies to date have not addressed questions relating to the “build” or “wear in” of advertising effects on smoking-related behaviors. Studies exploring the impact of different levels of advertising on smoking behaviors have typically examined associations between advertising exposure and behavior changes over differing periods, ranging from 3 months to 2 years. For this reason, it is not clear whether the effect of increased antismoking advertising on population smoking behavior occurs within a few weeks or requires longer durations of exposure. We investigated the effect of differing levels and durations of exposure to antismoking advertising on quitting outcomes, focusing on proximal indicators of behavior change expected to vary contemporaneously with advertising. 22 Public health media campaigns have been theorized to affect audiences in 1 of 2 ways: by providing new information that changes existing beliefs or by increasing the salience or accessibility of an existing belief. 23 In countries with long-running tobacco control programs, such as Australia, many smokers already possess favorable beliefs about quitting. 24 Therefore, we expected that the effects of antismoking advertising would be evident in increased salience of quitting-related thoughts. We also examined the relationship between advertising exposure and quit attempts, because it has been shown that increasing the rate of quit attempts in a population has been shown to be critical for reducing overall smoking prevalence. 25
