A price not worth paying : using causal effect modelling to examine the relationship between worklessness and mortality for male individuals in Scotland

Unemployed--Mortality--Scotland;Men--Mortality--Scotland;Logistic regression analysis

Clemens, Thomas Laurie ; Dibben, Chris ; Dibben, Chris

University:University of St Andrews

Department:Earth & Environmental Sciences and Geography & Sustainable Development (Schools of)

关键词: Unemployed--Mortality--Scotland;    Men--Mortality--Scotland;    Logistic regression analysis;   

Others  :  https://research-repository.st-andrews.ac.uk/bitstream/handle/10023/4036/ThomasClemensPhDThesis.pdf?sequence=3&isAllowed=y

来源: DR-NTU

【 摘 要 】

The research conducted in this thesis examines the relationship between forms ofworklessness (both active unemployment and inactivity due to sickness and disability) andmortality for working age men. Previous research has shown that being out of work isassociated with a greater risk of mortality relative to being in work. However, there remainsdebate as to whether this association is the result of a causal pathway leading fromworklessness to mortality or whether it reflects the ‘selection’ of individuals who are alreadyat greater risk of mortality from pre-existing poor health or other characteristics. In the UK,many studies rely on the use of ‘wear-off’ periods in which mortality events occurring withinfive years after the observation of employment status are ignored to allow the confoundingeffects of selection to diminish. Generally these studies concluded in support of a causalrelationship. In contrast, more recent studies making use of innovative methodologicaldesigns such as natural experiments and linked register and health datasets have found lessevidence for this explanation with many emphasising the role of confounding and selection.The thesis aims to firstly, examine the effectiveness of wear-off periods and secondly, todevelop an alternative counterfactual approach to examine the relationship betweenworklessness (both active unemployment and health related inactivity) and mortality. Thesequestions are addressed in three stand-alone papers.In the first paper, data from the Scottish Longitudinal Study and the England & WalesLongitudinal Study was used in logistic regression models which estimated the odds of deathin a given time period after the 1991 Census for those aged 35–64 in 1991. The odds ratiosfor the different economic positions (in work, unemployed, retired, permanently sick andother inactive) were compared, as well as the changes in risk associated with cumulativelyincreasing the length of wear-off prior to follow-up. No evidence was found of health relatedselection for the unemployed in 1991 suggesting that the use of the five year wear-off periodin many studies of mortality and unemployment may be an ineffective and unnecessarytechnique for mitigating the effects of health-related selection.The second paper examined men aged between 35 and 54 who were in work in 1991.Subsequent employment status in 2001 was observed (in work or unemployed) and therelative all-cause mortality risk of unemployment between 2001 and 2007 was estimated. Toaccount for potential selection into unemployment of those in poor health, a counterfactualpropensity score matching framework was used to construct unbiased and comparable samples of in work and unemployed individuals. Matching was based on a wide range ofexplanatory variables including health status prior to year of unemployment (hospitaladmissions and self-reported limiting long term illness) as well as measures of socio-economic position. The findings showed that unemployment was associated with a doubling(hazard ratio 2.1 95% CI 1.30 - 3.38) of the subsequent risk of mortality from all causesrelative to employment. This scale of effect was consistent across different samples and wasrobust controlling for prior health and socio-demographic characteristics. These findingswere interpreted as evidence that the often observed association between unemployment andmortality may contain a causal component.The second paper implemented a similar analytical design to address the lack of evidence forthe independent mortality effect of inactivity due to sickness. The results showed that themortality risk of economic inactivity due to sickness relative to active employment wassignificant (HR. 3.18, 95% CI 2.53-3.98) and suggest that economic inactivity due tosickness poses a mortality risk that is independent of prior health. The findings could beinterpreted in two ways; either economic inactivity due to sickness is worse for health thanactively seeking work or previous studies of unemployment and mortality haveunderestimated the true effect of being out of work generally.Across the three studies, the main contribution of the thesis is to reassert the importance ofworklessness as a determinant of individual mortality. In doing so the studies also foundlittle evidence of systematic confounding by either health or other characteristics. The thesisconcludes with a comprehensive discussion of the wider implications of the findings inrelation to both general methodological issues in observational epidemiology and possiblepolicy interventions that could be implemented to tackle work-related inequalities in malemortality.