[Calculation of disease-related costs in claims data analyses with the example of attention-deficit hyperactivity disorder. Comparison of methods].

: Claims data have proven useful for carrying out cost-of-illness studies. To avoid overestimating disease-related costs, only those costs that are related to a specific disease should be considered. The present study demonstrates two basic approaches for identifying disease-related costs. Using the example of attention-deficit hyperactivity disorder (ADHD), the advantages and drawbacks of expert-based approaches and those based on control groups are compared. Anonymized data from the "Techniker Krankenkasse" for 2008 were available for the study. The study population encompassed all ADHD patients and a control group that was five times bigger. Additionally, a systematic literature review was carried out on 65 relevant studies. Compared with the control group, disease-related costs were EUR 2,902 per ADHD patient on average. However, using the expert-based approach, costs were established to be EUR 923 lower. This is mainly because a comparison with an appropriate control group incorporates all costs for possible comorbidities and concomitant diseases. Both approaches have specific advantages and drawbacks, and when planning studies the respective limitations need to be considered.