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 socioeconomic groups. Potentially avoidable hospitalisations provide a useful tool for evidence-based population health needs analysis and health policy development.