Spatial analysis of Percutaneous Transluminal Coronary Angioplasty (PTCA) in Austria

Study objectives: To investigate the geographical distribution of Percutaneous Transluminal Coronary Angioplasty (PTCA) and morbidity for coronary heart disease, angina pectoris and myocardial infarction by spatial analysis of the standardized morbidity rates (SMR) on district level. To identify clusters by Moran's I Statistic and the Regional Spatial Autocorrelation Coefficient (RSAC) of Munasinghe and Morris. To investigate demand factor morbidity and supply factor health care infrastructure on the district level as reasons for geographical disparity. To describe characteristics of the cluster population and intervention centres. Study design: Retrospective record linkage study. Setting: All hospitals and cardiological centres in Austria (n = 150) which performed the Minimum Basic Data Set (MBDS). Patients: All Austrian residents who were diagnosed for myocardial infarction, coronary heart disease or angina pectoris in 1995 (n = 87,174). Measurements and main results: One positive PTCA cluster (all SMRs 0.96) and one negative PTCA cluster (all SMRs 0.59) were identified. They differed significantly in morbidity rate, intervention rate and available cardiological beds. The tendency to inverse relation between PTCA utilization and morbidity in the negative cluster supported the thesis of inverse care law. Austrianwide no significant correlation was found between the SMR of PTCA-application and both demand factor and supply factors. Nevertheless, differences between the clusters concerning number and capacity of intervention centres and density of specialists pointed to supply factors as reasons for geographical disparity. The ongoing trend of steady expansion of existing intervention centres and establishment of new ones will reduce the extent of geographical variation in future.