OBJECTIVE: So far, it remains unclear whether treatment of psychiatric comorbidity in medical inpatients is appropriately reflected in the German Diagnosis-Related Groups (DRG) system. Therefore, we investigated the relationship of psychiatric disorders and costs, returns, net gain, and duration of hospitalization in internal medicine inpatients. METHODS: For a period of 1 year, we analyzed costs, net gain and other outcome variables according to the DRG system for all inpatients of a university department of internal and psychosomatic medicine (n = 697). Psychiatric disorders were diagnosed by the treating physicians based on clinical criteria and results from the Patient Health Questionnaire (PHQ). With respect to the outcome variables, we compared three groups of patients with none, one, and more than one psychiatric disorder controlling for sociodemographic characteristics. RESULTS: The average total costs of the hospitalization (M +/- SD) for internal medicine patients without psychiatric comorbidity (4357 +/- 5312 euro), for patients with one psychiatric disorder, (4733 +/- 5389 euro), and for patients with more than one psychiatric disorder (7163 +/- 8277 euro) differed significantly (p = 0.0003). However, the increased costs for patients with psychiatric comorbidity were not related to elevated returns: the net gain for patients without psychiatric comorbidity was 457 +/- 2884 euro; in contrast, the treatment of internal medicine patients with one and more than one psychiatric disorder resulted in a net loss of - 260 +/- 2389 euro and - 348 +/- 3370 euro, respectively (overall group difference, p = 0.03). CONCLUSIONS: Additional work and expenses caused by patients with psychiatric comorbidity should be documented and reflected in the revenue systems. Practical self-report screening questionnaires may help to detect and treat psychiatric disorders in internal medicine inpatients as early as possible.
