[Diagnoses as the subject of health service research to analyse the morbidity of outpatients].

Health service research needs coded diagnoses of outpatients. The morbidity treated by physicians in ambulatory care is analysed every quarter on the basis of the diagnoses of about 1,2 Mio. patients by a randomised panel. Patient data combined with diagnoses, encounters and procedures demonstrate the variety of medical care provided. Relevant research questions are for instance the influence of co-payment on the structure of diagnoses or the prevalence of heart diseases in the offices of general practitioners. The comparison of prescribing patterns and diagnoses demonstrates the predominantly probatory therapy with proton pump-inhibitors in the case of gastroesophegal reflux disease. The plausibility and validity of disease documentation are permanently observed by regular checks.