Background: Routine data analyses are becoming increasingly important for health policy decision making. However such databases often vary in data quality, completeness and accessibility. The aim of this study is to describe the quality of a large outpatient healthcare database, the process of data extraction and to give a brief overview of data-structure with focusing on provider-type and disease severity in an example of the treatment of depressive disorders.

Method: The quality of the database is described and diagnosis rates of depression in outpatient care (ICD-10 diagnoses F32/33) in relation to the provider-type (i.e. general or somatic physician vs. physicians specialized in mental-health vs. psychotherapist) were calculated using Cramers V as a measure for effect size.

Results: The database consisted of 2,383,672 cases from 2015. Most depressive patients were diagnosed and treated by general or somatic physicians. A clear relationship between the severity of depression and provider-type is shown. In contrast to psychotherapists or physicians specialized in mental-health, general or somatic physicians diagnose a higher rate of unspecified depressive episodes.