Potentially avoidable hospitalisations in New Zealand, 1989-98.

OBJECTIVE: To describe potentially avoidable hospitalisation in New Zealand, including recent trends and variations between groups differentiated by age, gender, ethnicity and degree of deprivation.
METHOD: Hospital discharges among people aged 0-74 years for the years 1989-98 were classified as 'potentially avoidable' or 'unavoidable' based on the ICD9-CMA code of the principal diagnosis. Potentially avoidable hospitalisations (PAH) were further subcategorised according to the intervention involved--primary prevention, ambulatory care or injury prevention.
RESULTS: By 1998, one in three of these hospitalisations was theoretically avoidable--two-thirds of these through more effective primary health care services. Although in practice only a proportion of these could realistically have been avoided, these estimates reveal considerable scope for further reduction in the incidence of serious disease and injury. Maori and Pacific people had age-standardised PAH rates approximately 60% higher than European and other New Zealanders. Similar discrepancies exist by socio-economic deprivation. Had all New Zealanders enjoyed the PAH rates of the most advantaged 40% of the population, 28% fewer potentially avoidable hospitalisations would have occurred in 1998, some 26,000 hospital admissions.
CONCLUSION: This analysis has revealed significant scope for the health sector to contribute to population health gain and, in particular, to improvement in equity of outcomes across ethnic and socio-economic groups. Potentially avoidable hospitalisations provide a useful tool for evidence-based population health needs analysis and health policy development.