Scottish Health Survey - topic report: The Glasgow Effect

6. Overall Conclusions

This study sought to examine the extent to which residence in Glasgow was significantly and independently associated with the risk of a range of health behaviours and both mental and physical health outcomes, and whether any associations were explained by area level deprivation, socio-economic, behavioural, biological, relationship and social mobility factors.

Table 4 shows the percentage of the difference between Greater Glasgow and Clyde and the rest of Scotland which was explained by adjusting for each group of explanatory variables. All the residence effect has been explained when 100% of the difference has been explained. For different outcomes the percentage of the difference explained by SIMD compared to SIMD and socio-economic variables varies; much more of the residence effect is explained by SIMD for self-assessed health than depression, but both are fully explained after further adjusting for the socio-economic variables.

The results have shown that even when area based deprivation and a range of other socio-economic factors are taken into account, there remains a significant excess risk associated with residence in Glasgow for anxiety, GHQ, self-reported doctor diagnosed heart attack and, for men, being overweight. Of these, all of the excess risk can be explained in terms of behavioural and biological characteristics for being overweight and having a high GHQ score. However, for two important outcomes relating to both physical and mental health, no explanation can be derived for the excess risk of doctor diagnosed heart attack or anxiety from the wealth of information collected in the Scottish Health Survey.

The socio-economic variable which had the largest impact on predicting health outcomes when each socio-economic variable was included as the only socio-economic variable in the final model for each outcome was economic status.

Although it is encouraging that differences in many of the adverse health behaviours were explained by the differing age and sex distributions, the differences for many health outcomes were explained by either area or individual level socio-economic factors. This underlines the importance of improving both the area and individual level socio-economic circumstances of those experiencing poverty and deprivation. However further research is needed into the reasons behind the increased levels of anxiety and heart attacks found in Greater Glasgow and Clyde as these are not fully explained by socio-economic circumstances.

There are some limitations to the study, such as the use of so many self-reported measures; however as this was the same for residents of Greater Glasgow and Clyde and the rest of Scotland the results are still comparable between the two regions. Complete case analyses were carried out; although weights were used to ensure the participating sample represented Scotland, this does not account for item non response within participants, which occasionally led to different results when the same model was run using the nurse/blood sample and the complete sample. The number of participants who had suffered strokes or heart attacks were small, and this meant certain biological relationships could not be investigated. Finally this is a cross-sectional dataset, so it is not possible to draw conclusions regarding the direction of effects. However the many advantages of the study outweigh the disadvantages, such as the large sample size and breadth of information available in the Scottish Health Surveys, allowing these analyses to be carried out, extending previous work which only investigated the extent of socio-economic variables in explaining differences between Glasgow and the rest of Scotland. An additional advantage is the use of a more spatially-specific variable to examine the effect of area-level deprivation.