The Townsend Index of Material deprivation and Mosaic provide two different ways of profiling an individual's social circumstances in terms of the area in which they live. Amongst patients in the large primary care dataset of THIN, we have shown clear socioeconomic differences in smoking prevalence according to both of these measures. When using the Townsend Index, we found smoking prevalence to be progressively higher in those living in more deprived areas, in accordance with previous cross-sectional studies carried out in the UK that used the Townsend Index to indicate deprivation. When using Mosaic groups, the likelihood of being a current smoker is highest in groups F and G, groups that are dependent on social benefits, compared with group A, which encompasses the most affluent members of the population.
However, the range of estimates of smoking prevalence is greater across the 11 Mosaic groups and even more so across the 61 Mosaic types compared to the difference across Townsend quintiles. For example, the highest prevalence observed in the Mosaic types was 42.7%, whilst the Townsend quintile with the highest proportion of current smokers had a prevalence of 32.7%. Smoking prevalence in the Mosaic group with the lowest proportion of current smokers was 8.6%, compared to 13.5% in the lowest Townsend quintile. Mosaic paints a worse picture of social disparities in smoking prevalence in the UK than previously-used measures of social class, and may be a useful tool for distinguishing the characteristics of groups with a particularly high smoking prevalence.
A Mosaic classification and/or Townsend quintile was missing for some patients in this analysis, though the odds of being a smoker for these are not extreme, suggesting that this data was missing at random and a high-prevalence group has not been missed. It is unclear why this information was missing for some people, but it may be that these patients' postcodes were not recorded by their general practice, and therefore EPIC was unable to map them to the area-based measures of deprivation.
An assumption has been made that patients not classified as current smokers are non-smokers, including those with no smoking-related Read codes documented in their medical records. This may lead to an underestimation of smoking prevalence. However, it has been shown that prevalence figures obtained using this assumption are reasonably reflective of those suggested by nationally-representative surveys, and the majority of patients with missing smoking records in THIN are either ex- or non-smokers. The differences in the proportion of patients with a smoking record in different categories of each measure of deprivation were small and unlikely to have contributed to any great extent to the socio-economic differences in smoking prevalence reported.
The Mosaic classification, which groups individuals into 61 categories, may be quite a cumbersome system to use as a socioeconomic measure in most statistical models and, as noted already, little information is available from Experian about how the classification is derived, limiting assessment of the validity of their approach and the potential to replicate it. Some variables indicating individuals' health status, which may be related to past or current smoking behaviour, are used to derive Mosaic; this may confound identification of the groups most and least likely to smoke. In the interpretation of Mosaic it is also important to be aware that the classification is an area-level measure, based on postcode areas of approximately 15 households, and that the characteristics of any given type will only apply to the majority of individuals of that type - not all of them. It is also important to note that the estimated odds ratios presented in this study will overestimate the respective risk ratios across the groups as smoking prevalence is 20.8% overall, not a rare outcome. In calculating odds ratios, the use of the Mosaic group or type with the lowest smoking prevalence as the reference category will have maximised the difference in odds ratios observed across categories, though this is an appropriate approach for demonstrating the wider extremes in smoking prevalence that can be identified using Mosaic.
Those Mosaic types with a higher prevalence of smoking were characterised by minimal levels of education, low income, and manual occupations. These findings are consistent with existing knowledge, acquired using individual measures of socioeconomic status, such as income, education, and occupation. However, Mosaic provides further detail - the Mosaic types with highest prevalence do not have access to a car, have little community support, are debt-ridden and tend to spend a lot of time in front of the television. Some of these factors seem likely to contribute to difficulty in quitting smoking, suggesting, perhaps, difficulty in accessing cessation support and advice. These findings provide some insights into how these groups might be targeted, such as through mobile smoking cessation services and provision of transport to enable access to existing services, or through television campaigns, utilising the principles and techniques of social marketing to ensure that smokers are targeted with appropriate cessation interventions. There is some evidence that providing cessation services in novel settings, such as community pharmacies, dental surgeries or workplaces, may be effective in engaging large numbers of smokers, though more research is needed to determine whether these are successful in reaching disadvantaged groups in particular. Similarly, mass media campaigns may have a valuable role to play in encouraging smoking cessation, though again there is limited evidence whether such campaigns are effective in reaching large numbers of the most disadvantaged smokers[18, 19]. Given that many Mosaic groups with the highest smoking prevalence are in debt, offering financial incentives may provide a useful tool to engage these groups in cessation services. Existing research suggests such incentives may indeed increase the number of disadvantaged smokers who attempt to quit, and the number who succeed in doing so, though again further studies would be of benefit.
This study is one of the first to look at the association between Mosaic and smoking prevalence, and certainly the first to do so on such a large scale. In conclusion, the Mosaic classification system has been found to be a useful tool in examining the disparities in smoking prevalence between different socioeconomic groups within the UK, with those in the group with the highest smoking prevalence being over four times as likely to smoke as those in the group with the lowest prevalence. Mosaic is potentially useful for identifying the characteristics of groups of heavy smokers which can then be used to tailor cessation interventions to ensure these are as successful as possible and make the best use of resources. Though Mosaic only classifies individuals living in the UK, a similar approach to the use of market research and consumer segmentation intelligence may provide a means to identify groups of people with high smoking prevalence in other countries and target them with appropriate cessation interventions.