Explanations for socio-economic differentials in mortality

Socio-economic differentials in mortality are examined using the explanatory framework advanced by the Black Report. The evidence reviewed largely relates to studies carried out in Britain, although data from other European countries and the United States have also been considered. The many possible forms of artefactual distortion of associations between socio-economic status and mortality risk are examined and judged to have little effect; if anything, artefactual factors mean that conventional ideas about the magnitude of socio-economic differentials in mortality are an underestimate. Social selection is also considered to have little effect. Neither intragenerational downward drift nor direct intergenerational selection contribute significantly to the size of the differentials. Indirect selection has yet to be evaluated, although whether ft should be considered as a form of health selection rather than one form of accumulated disadvantage is unclear. Behavioural factors, while making important contributions to mortality risk, do not adequately account for the differences between social groups. Materialist factors, that is differential exposure to physical hazards determined by the distribution of income and opportunity, are an attractive explanatory category, since the persisting (or growing) socio-economic and geographical mortality differentials, seen during a period of broad secular declines in mortality rates, would be the anticipated outcome of their action. However, neither the social processes determining risk exposure nor the mechanisms by which exposures produce disease are well understood. Progress jn this area will depend upon studies which can examine how exposures interact and accumulate over the course of life to produce the observed pattern of mortality risk.