[Index numbers of ambulatory care utilization. Methodical and content aspects of the value of survey data].

Index numbers of the utilization of outpatient treatment are essential for differentiated health reporting. The established doctor fulfills nodal, coordinating and regulating functions. Therefore numbers reflecting those functions are also indicators for other types of health services. They allow conclusions about motives, preferences and attitudes of the population. Based on two representative population surveys (the Socio-economic Panel and the National Health Survey of the German Cardiovascular Prevention Study) the index numbers Quarterly-Utilization, Contact-Frequency and User-Frequency are analysed. Taking the example of age and sex differences the influence of differing research designs on the validity and possibility of interpretation of the different index numbers are discussed.