Assessing patients’ acceptable and realised distances to determine accessibility standards for the size of catchment areas in outpatient care

Healthcare planning aims to ensure availability of care in a needs-based, evenly distributed and locally available manner. However, many planning mechanisms lack accessibility standards. To determine standards, catchment areas must be derived from health-related travel assessments and a population's distance acceptance for different medical specialisation levels. We estimated distance acceptance using representative cross-sectional survey data (n = 1.598). Moreover, we used utilization data covering 88% of the German population (2014/15) to calculate realised travel distances for six medical specialties (n = 676.255.605 cases). We specified a gravity-based distance decay function and estimated regression-based distance thresholds from both samples. Realised distances were mostly below 30 min (90% of cases) indicating appropriate mean accessibility. The 5% observed distance threshold was between 23.7 min for GPs and 47.6 min for dermatologists. Depending on medical speciality, distance acceptance was mainly determined by distance, age, activity level and town size for GP visits and by health and income for specialist care. 5% acceptance thresholds varied between 27.9 min to GPs for elderly patients and 51.6 min to orthopaedists for younger patients. Acceptable distances for 90% of the population were 6 (8) minutes to GPs (specialists). The variation of thresholds, which depended on socio-demographic and health variables and the population share that is fully accepting, illustrates that healthcare planners should move beyond averages to realise equal access for equal need.