An analysis of the extent to which socio-economic deprivation explains higher mortality in Glasgow in comparison with other post-industrial UK cities, and an investigation of other possible explanations

Background: Despite the important, and well-established, link between poverty and poor health, previous research has shown that there is an ‘excess’ level of mortality in Scotland compared to England and Wales: that is, higher mortality seemingly not explained by differences in levels of socio-economic deprivation. This excess has been shown to be ubiquitous in Scotland, but greatest in and around Glasgow and the West Central Scotland conurbation. To investigate this further, the aims of this research were: first, to compare levels of mortality and deprivation – and, specifically, the extent to which differences in the latter explain differences in the former – between Glasgow and its two most comparable English cities, Liverpool and Manchester; and second, to investigate, by means of collection and analyses of new population survey data, some of the many hypotheses that have been proposed to explain Scotland’s, and Glasgow’s, ‘excess’ levels of poor health. Methods: Geographic Information System (GIS) software was used to create small geographical units for Glasgow comparable in size to those available for the English cities (average population size: 1,600). Rates of ‘income deprivation’ were calculated for these small areas across all three cities. All-cause and cause-specific standardised mortality ratios were calculated for Glasgow relative to Liverpool and Manchester, standardising for age, sex and income deprivation decile. In addition, a range of historical socio-economic and mortality data was analysed. Three of the previously suggested explanations for excess Scottish mortality were investigated: lower levels of social capital; a lower ‘Sense of Coherence’(SoC); and a different ‘psychological outlook’ (specifically, lower levels of optimism). To do so, a representative survey of the adult population of Glasgow, Liverpool and Manchester was undertaken. Previously validated question sets and scales were used to measure the three hypotheses: levels of social capital were assessed by means of an expanded version of the Office for National Statistics (ONS) core ‘Social Capital Harmonised Question Set’ (covering views about the local area, civic participation, social networks and support, social participation, and reciprocity and trust); SoC was measured by Antonovsky’s 13-item scale (SOC-13); and levels of optimism were assessed using the Life Orientation Test (Revised) (LOT-R). The data were analysed by means of multivariate regression analyses, thus ensuring that any observed differences between the cities were independent of differences in the characteristics of the survey samples (age, gender, social class, ethnicity etc.). Results: The deprivation profiles of Glasgow, Liverpool and Manchester were shown to be very similar: approximately a quarter of the total population of each city was classed as income deprived in 2005, with the distributions of deprivation across the cities’ small areas also extremely alike. Despite this, after statistical adjustment for any remaining differences in deprivation, premature deaths (<65 years) in the period 2003-07 were 30% higher in Glasgow compared to Liverpool and Manchester, with deaths at all ages almost 15% higher. This excess was seen across virtually the whole population: all adult age groups, males and females, and among those living in deprived and non-deprived neighbourhoods. However, a difference was observed between the excess for deaths at all ages and that for premature deaths. For the former, the 15% higher mortality was distributed fairly evenly across deprivation deciles, and the greatest contribution (in terms of causes of death) was from cancers and diseases of the circulatory system; in the latter case, the excess was much higher in comparisons of those living in the more, rather than less, deprived areas (particularly men), and was driven in particular by higher rates of death from alcohol, drugs and suicide. Importantly, the excess appears to be increasing over time. The analyses of the survey data showed SoC to be higher, not lower, among the Glasgow sample compared to those in both English cities. Levels of optimism (measured by the LOT-R scale) were very similar in Glasgow and Liverpool, and higher than that measured among the Manchester sample. Although not all aspects of social capital presented the Glasgow sample in a more negative light, Glasgow respondents were, however, characterised by lower levels of social participation, trust and reciprocity. A number of these differences were greatest in comparisons of those of higher, rather than lower, socio-economic status. Conclusions: As currently measured, socio-economic deprivation does not appear to explain the differences in mortality between the cities: there is a high level of ‘excess’ mortality in Glasgow compared to the English cities. While many theories have been proposed to explain this, on the basis of the analyses included within this thesis, it seems highly unlikely that two of these – lower Sense of Coherence and a different psychological outlook (optimism) – play a part. However, it is possible that differences in aspects of social capital may play a role in explaining some of the excess, particularly that observed in comparisons of less deprived populations. The concluding chapter of the thesis argues that excess mortality in Scotland and, in particular, its largest city, is a deeply complex phenomenon: the causes, therefore, are likely to be equally complex and multifactorial. It is postulated that, given the fundamental link between deprivation and mortality, the essence and reality of deprivation experienced by sections of Glasgow’s population may not have been fully captured by the measures employed within research to date. More speculatively, the role of history may be important in seeking to identify the potentially different, unmeasured, facets of deprivation experienced by people in Glasgow compared to those in Liverpool and Manchester. It is also possible that protective factors (relating to, for example, ethnicity and social capital) may be at work in the two comparator English cities. However, given that excess mortality has been shown for all parts of Scotland compared to England & Wales, and not just Glasgow, this is not in any way a complete explanation.