Influence of bed supply and health care organization on regional and local patterns of diabetes related hospitalization.

This paper undertakes both a macro- and micro-scale analysis of the influences exerted by the health care system on patterns of hospitalization. The health disorder of diabetes mellitus is used as the case study and the analyses are based on New Zealand data sets. The article first examines the extent to which both the supply and organization of primary and secondary health care affect rates of hospitalization. The macro-scale analysis investigates the applicability of Roemer's Law to regional variations in diabetes hospitalization. The organizational control of hospital utilization via doctor gatekeeping functions and interaction between health services are then examined at the local level. This analysis assumes a population based approach using the Canterbury Register of Insulin-treated diabetic persons as the study population. Diabetes discharge rates were found to be most highly correlated with hospital bed supply in 5 of the 8 years studied (1979-1986). Stepwise regression analysis indicated area rates of diabetes hospitalization were significantly influenced by resource factors even after controlling for differences in the socio-demographic characteristics of the area populations. This confirmed the presence of Roemer's Law at the aggregate level with rates of diabetes hospitalization appearing to have more to do with the availability of medical resources than to population needs. At the local level, hospital admission patterns were found to vary by general practitioner age, practice type found to vary by general practitioner age, practice type and diabetic caseload. Overall, insulin-treated diabetic patients most likely to be hospitalized were those in the care of young doctors new to general practice, and those who attended doctors who had small diabetic caseloads. Solo practitioners had the lowest rates of patient hospitalization. There were marked disparities in patient access to specialist diabetes education and clinical outpatient services by patient age, duration of diabetes and attendance on primary care. Overall, no significant differences were found in the propensity for hospitalization between users and non-users of these specialist services. This does not imply however, service ineffectiveness but rather is indicative of the complexity of the local diabetes care organization and the differing needs of the insulin-treated diabetic population within the community as a whole.