180 7.1 Introduction
The role of mass media campaigns in tobacco control has been introduced in Chapter 1. As explained in section 1.6.2, international evidence suggests that tobacco control mass media campaigns can increase the chances of quitting and reduce smoking prevalence; however the evidence is not conclusive. Furthermore, very few academic studies have looked at the effectiveness of mass media campaigns in the UK, none of which have been published in the past decade.173, 272-274
Many government or charity-funded campaigns undergo some evaluation of their immediate impact, but this is usually on the basis of small scale quantitative or qualitative surveys conducted over very short periods of time just before and after the campaign, without formal inferential statistical analysis; as such there is a dearth of UK-specific evidence.
In addition, evidence from the US suggests that advertising for NRT may also influence quitting, but no peer-reviewed studies have been undertaken of its effect on quitting behaviour in the UK or elsewhere.89, 90
As a result of the recent cuts in funding for tobacco control mass media campaigns, there is an urgent need to evaluate the effectiveness of both types of campaign in the UK. Investigating the effect of tobacco
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During the course of my PhD research, I therefore obtained funding to conduct analyses of the impact of both types of mass media campaigns.
ASH UK provided two months funding to carry out a preliminary descriptive analysis of the potential impact of both types of campaigns on a wide range on indicators of quitting behaviour. The report of this work is attached in Appendix 9.10. The report hinted at effects of both types of campaigns, but underlined the need for formal statistical analysis using high quality data to confirm and quantify the magnitude of those effects. I subsequently led on a project grant obtained from the Cancer Research UK Tobacco Advisory Group to conduct such an analysis. The results of this study are presented in this chapter.
The aims of the study were to assess the association between tobacco control advertising and advertising for NRT purchased by the pharmaceutical industry, and a range of sensitive indicators of quitting behaviour which seemed likely to respond to changes in advertising: calls to the free NHS smoking helpline, and rates of prescribing and over-the-counter (OTC) sales of NRT.
7.2 Methods 7.2.1 Exposure Data
This study used time series data on television ratings points (TVRs), a standard broadcasting industry measure of the audience which views a television programme or advert, as its measure of exposure to anti-tobacco mass media advertising and smoking cessation medication advertising. A TVR is defined as the percentage of a particular audience that has seen a commercial break. The measures of exposure to advertising in this study were:
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TVRs purchased for tobacco control campaigns by the Central Office of Information (COI, on behalf of the government), Cancer Research UK and the British Heart Foundation (the three main purchasers of such advertising during the time period) each month from January 2002 to May 2010, and
TVRs purchased by pharmaceutical companies to advertise NRT each month from January 2005 to December 2009.
The tobacco control TVR data used in this study include all mass media campaigns related to smoking, including those targeting young people and related to smokefree legislation, as all of these campaigns may have influenced quitting behaviour. The TVR data nominally cover the whole of the UK, but due to devolved responsibilities for health promotion media campaigns in the UK, the COI TVR data primarily cover England only, with some overlap into other home nations through advertising in the press. The TVRs overlapping into Scotland and Wales have therefore been removed. Some of the outcome data cover England only, but due to the makeup of the UK‘s TV regions, TVRs for Wales could not be separated from those for England.
The pharmaceutical company TVR data are available for the whole of the UK but, to allow better comparison with the government-funded campaign data, only data on England and Wales have been used in this study.
The TVRs for England and Wales were calculated by summing population-weighted values of TVRs for each television region in England and Wales.
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Advertising spend data are also available. For this study, however, TVR data were selected over spend data, as these ought to provide a more accurate representation of exposure to campaigns (as the cost of advertising is likely to vary over time) and were available for a longer time period. However, spend data were compared with TVR data to ensure that there would be no significant differences in the results depending on the exposure used. Appendix 9.9 shows that the trends in these two advertising exposures are extremely similar.
7.2.2 Outcome data
This study used time series data on three outcome measures which were available on a monthly basis for a long time period and seemed likely to be most responsive to changes in advertising exposure: calls to the NHS stop smoking helpline, prescribing of NRT, and OTC sales of NRT. The preliminary report for ASH also included quit attempts based on the STS and brief stop smoking advice data from THIN, but as explained in Chapter 2, these seem likely to be of limited quality on a monthly basis and were and are therefore likely to have influenced calls to the helpline. This study uses the number of calls to the NHS helpline per month from November 2004 to June 2010.