LARGE DIFFERENCES IN OBSTETRICAL INTERVENTION RATES AMONG DUTCH HOSPITALS, EVEN AFTER ADJUSTMENT FOR POPULATION DIFFERENCES

Within the framework of the 'Obstetric Peer Review' project (Verloskun dige Onderlinge Kwaliteitsspiegeling, VOKS) statistical models have be en developed to predict department specific intervention rates, based on the distribution of risk factors in each department. Subsequently t he difference between the expected number of interventions (labour ind uctions, caesarean sections and vaginal operative deliveries) and the actual numbers were calculated for each year and subpopulation defined by the level of prematurity. Data used were available from the Perina tal Database of the Netherlands (Landelijke Verloskunde Registratie, L VR) concerning the years 1988-1992. Even after adjusting for many clin ical risk factors the interdepartmental differences of intervention ra tes are both clinically relevant and statistically significant. It was also obvious, especially for the term population, that departments sh owed a consistent pattern with respect to the difference between their expected and observed intervention rates over these 5 years.