Trends and patterns of avoidable hospitalisations in New Zealand:1980-1997.

AIMS To describe and analyse the trends in (and pattern of) hospitalisations for medical conditions that could be avoided by adequate primary care. METHODS Using public hospital inpatient discharges data, avoidable hospitalisation rates are derived for each of the four time points around the 1981, 1986, 1991, and 1996 censuses (for 29 geographical regions, 7 functional age groups, and 12 medical conditions). All rates are standardised for age compositional differences, using the 1996 New Zealand age-composition as the standard. Relative avoidable hospitalisation rates are derived using North Shore as the reference region. RESULTS Avoidable hospitalisation rate increased during the 1980-97 period. Regional variations narrowed during 1980-97 because some regions experienced greater increases in avoidable hospitalisations than others. Regions with higher avoidable hospitalisations tended to have greater proportion of sole Maori populations. The young and old had higher rates than other age groups. Avoidable hospitalisation increased for all medical conditions but asthma and immunisable conditions. CONCLUSIONS The increase in avoidable hospitalisation in New Zealand between 1980 and 1997 coincided with the major health reforms, economic restructuring, and welfare reforms of the 1980s and early 1990s.