Material deprivation as marker of health needs

A relationship between socio-economic status and health has been widely documented both by individual-level and ecological regression studies. We addressed the problem known in the literature as Mutual Standardization using a material deprivation index as predictor of health needs and comparing results when adjusting or not the health outcome and the deprivation index for the same confounding variables. We focus on non-linear hierarchical models. We take as example the the issue of introducing socio-economic indicators in national or regional resources allocation formulas. We fitted a series of models with different data hierarchies to evaluate both the individual effect and the aggregate (census block) effect of material deprivation on heath status, disentagling the individual from the contextual effects. Individual mortality records came from the Florence census cohort 1991-1995 which is part of the Tuscan Longitudinal Study. Data on socio-economic factors derived from individual records of the 1991 census. Our results suggested that after adjusting for age, material deprivation is a good predictor of health needs both at individual and at aggregate level (census block). The presence of a contextual effect increases the interest in using deprivatin in the allocation formula, since it would permit a better distribution of resources to disadvantaged micro-areas. In the present paper, we stress the need to estimate the association between deprivation and health appropriately adjusting for age. The ideal goal would be having information at small geographical level on the joint distribution of age and deprivation, which permits to age-standardize both the response and the predictor. A temporary solution should be to regress crude mortality rates on deprivation and age. The current common practice, in absence of individual data, to regress standardized mortality on material deprivation may be inappropriate.