How much does health care contribute to health inequality in New Zealand?

OBJECTIVE: To quantify the contribution of health care to ethnic and socio-economic inequalities in health in New Zealand in 2000-02, using the concept of 'amenable' mortality (deaths at ages 0-74 years from causes responsive to health care). DATA SOURCES AND METHODS: Mortality data for 2000-02 were provided by the New Zealand Health Information Service and 2001 Census population data were provided by Statistics New Zealand. The classification of ICD-10 codes as amenable or non-amenable used in the Australian and New Zealand Atlas of Avoidable Mortality (2006) was adopted. Ethnicity was categorised as Maori, Pacific or European/Other. Socio-economic position was measured using a Census-based small area deprivation index, the NZDep2001. Mortality rates were standardised for age by the direct method for the ethnic group comparisons, and for both age and ethnicity for the deprivation group comparisons. The contribution of health care to health inequality was then quantified as the ratio of the difference in standardised amenable mortality rates to the difference in standardised total mortality rates (in the age group 0-74 years) between relevant groups.
RESULTS: Amenable causes of death were estimated to account for 27%, 34%, 33% and 44% of the total mortality disparity (0-74 years) for Maori males, Maori females, Pacific males and Pacific females respectively, relative to their European/ Other counterparts (adjusting for age). The corresponding proportions for the 'deprived' population relative to the 'non-deprived' population were 26% (males) and 30% (females), adjusting for age and ethnicity.
CONCLUSIONS: Amenable causes of death made a substantial contribution to differences in mortality in the 0-74 year age range between ethnic and socio-economic groups in New Zealand in 2000-02, ranging from 26-44% depending on the group.