[Health service costs in people with severe mental illness: patient report vs. administrative records]

During the last years, self-reported measures of mental health service use for people with mental illness have become increasingly popular. Yet, little is known about the differences between patient report and administrative records and how these may be explained.

82 of the 294 participants of the study "Outcome monitoring and outcome management in in-patient psychiatric care" were insured with a major statutory health insurance (AOK Schwaben) and gave informed consent to researchers to access their AOK administrative records. For a 6-month period prior to psychiatric hospital admission, these were compared to the costs as assessed via the German version of the "Client Sociodemographic and Service Receipt Inventory" (CSSRI-EU).

Median total monthly treatment costs were 112.23 € (patient-reported) vs. 254.23 € (administrative records; paired Wilcoxon Z = - 3.75; p < 0.001). Cost differences were independent of participants' socioeconomic and clinical characteristics. Correspondence between total treatment costs was substantial for total costs (ρ = 0.48; p < 0.001) and all subtypes of costs (in- and outpatient services, medication).

Despite a general tendency to underreport service use, self-report data adequately reflect the "real" health service costs as evident in the health insurance records of people with mental illness.