Empresas Operadoras Tercerizadas

Evaluation of tobacco control policy requires high quality and timely data on smoking and smoking cessation behaviour both in the general population and in relevant sociodemographic groups. The data used should be relevant, valid and representative of the population being studied. As highlighted in section 1.7.3, it is desirable to conduct evaluations using a range of outcome measures, and therefore it is worthwhile exploring a whole variety of data sources to obtain outcome measures.

Data may be available from existing sources including national or regional surveys, or routinely collected data such as primary care data. The advantage of survey data is that they may be cheap or free for researchers to access, and are likely to be available for a long time period. However, there are significant disadvantages to this type of data, including potential reporting and recall bias (participants may not report smoking behaviour accurately or may misremember it), potentially inadequate sample sizes, and the fact that most surveys are carried out only annually.

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The use of routinely collected data is likely to overcome many of the drawbacks of survey data: they may contain objective measures (thus information on smoking and smoking behaviour. Many have not been used in the evaluation of individual tobacco control policies. The suitability of a group of these existing data sources for the evaluation of tobacco control policy is discussed in detail in Chapter 2.

If suitable existing data are not available, specifically-collected data may be more appropriate, as these can be tailored to the needs of the allow sufficient time for pre-policy data collection, and may be affected by unexpected changes in the content or timing of policies.

It may be the case that insufficient data to draw definitive conclusions about the effects of a policy are available. This may particularly be the case in countries where the infrastructure and funding for data collection and research are limited; however, as is explained in Chapter 2, even many types of existing data in England and the rest of the UK have

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substantial limitations for the evaluation of tobacco control policy. Where national data and, thus, national evidence are limited, it is useful to take international evidence into account. For example, although there are few studies on improvement in health outcomes following the implementation of smokefree legislation in England, taking into consideration the reported impact of smoking bans in international settings could lend support to arguments that such bans have a positive impact on health outcomes.

1.7.7 Case study: The ITC Project Background

The biggest tobacco control policy evaluation project undertaken to date is the ITC Project. It has many of the features described above as important to good policy evaluation; however, it also has a range of limitations. It provides a useful case study to demonstrate the importance of the various evaluation features described in this section.

The ITC Project was designed to evaluate FCTC policies and provide evidence on the impact of national tobacco control policies on psychosocial indicators (such as beliefs and attitudes and perceived risks of smoking) and smoking behaviours (e.g. quit attempts). It began in 2002 in the UK, United States, Canada and Australia, and now comprises 20 countries.

Design

The ITC Project uses a longitudinal survey design with multiple country controls and theory-based mediational models. It collects data on cohorts of approximately 2000 smokers in each country. The cohorts are replenished for each wave of data collection to ensure that the sample size is retained regardless of attrition. The survey is comprehensive, comprising questions on mediators, including policy-specific variables (such as warning

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label salience) and psycho-social mediators (such as beliefs, attitudes and quit intentions), as well as questions on smoking behaviour. The conceptual model of the project assumes that each policy has an influence on behaviour through a specific chain of psychological events. In other words, it is assumed that the impact of a policy on behaviour is mediated by psycho-social factors.

Strengths

The ITC Project has several strengths which make it able to provide strong evidence of the effects of tobacco control policies in a range of countries. The longitudinal design allows the identification of temporal relationships, which would not be possible with a cross-sectional survey design. Further to this, collecting data at several time points means that temporal trends can be taken into account. The country controls help to disentangle policy effects from secular trends and confounding events. In addition, using the same method of data collection across all countries enables comparisons between them. Finally, as the surveys comprise behavioural and mediational variables, both the impact of policies and the mediators for policy impacts can be investigated.

Limitations

A key limitation of the ITC Project is that it is based on survey data, which is prone to recall and reporting bias. The results of the project would therefore benefit from triangulation with evaluations based on objective data. There is also high attrition between survey waves.¹⁴⁸ Further to this, the ITC data tend to have insufficiently large sample sizes to evaluate sub-national policies, which are common in some of its countries, such as the US.¹³²

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Perhaps the most significant limitation of the ITC Project is the frequency and regularity of data collection. In some countries, only one wave of data has currently been collected, and thus evaluations cannot incorporate longitudinal data. In the ITC countries where there have been more waves (e.g. up to 8 in the UK, Canada and Australia), the surveys have been irregular, with data collection tending to span many months.

Thus it is more difficult to take accurate account of temporal trends, or to detect the effect of specific policies, which may be gradual, occur with a lag, or be confounded by other events. Further to this, the surveys are often conducted at different times of year from one wave to the next, and responses may therefore be influenced by seasonal effects on quitting behaviour and intentions. These problems are likely to be only partially mitigated by the country controls given that they are common across countries. These issues are primarily due to the significant costs of running such large, detailed surveys, and highlight the potential value of data which are routinely collected.

1.8 Summary

The burden of smoking in the UK is, despite significant decreases in smoking prevalence over recent decades, enormous. In recent years, a comprehensive framework of tobacco control policies has been implemented in the UK to reduce the burden, and that framework continues to develop. The evaluation of population-level tobacco control policy is necessary to establish which policies are effective and how they may be improved in order to maximise their impact.

A range of study design features that will improve the quality of an evaluation have been highlighted in this chapter, including the use of control groups and long time series data with multiple pre- and post-policy

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observations. Time series analysis has been highlighted as a valuable statistical method in the evaluation of policy.

Various types of data may be used in the evaluation of tobacco control policy; however, all data sources have strengths and limitations.

The combination of the information generated by different studies using a range of outcomes is likely to increase the validity of overall conclusions as to the effect of a policy.¹³¹

The ITC Project is the best attempt to date to integrate all of the features of good policy evaluation into one design, and provides extensive data on smoking, quitting behaviour and attitudes in the UK and other countries. However, it has various limitations. The work in this thesis will complement the ITC Project, by identifying other high quality data and methods that can be used to evaluate tobacco control policy in England.