Abstract
Aims. New reimbursement schemes for inpatient mental health care are imminent in the UK and Germany. The shared intention is to reflect cost differences between patients in reimbursement rates. This requires understanding of patient characteristics that influence hospital resource use. The aim of this review was to show which associations between mental health care per diem hospital costs and patient characteristics are supported by current evidence. Methods. A systematic review of the literature published between 1980 and 2012 was carried out. The search strategy included electronic databases and hand-searching. Furthermore, reference lists, citing articles and related publications were screened and experts were contacted. Results. The search found eight studies. Dispersion in per diem costs was moderate, as was the ability to explain it with patient characteristics. Six patient characteristics were identified as the most relevant variables. These were (1) age, (2) major diagnostic group, (3) risk, (4) legal problems, (5) the ability to perform activities of daily living and (6) presence of psychotic or affective symptoms. Two non-patient-related factors were identified. These were (1) day of stay and (2) treatment site. Conclusions. Idiosyncrasies of mental health care complicated the prediction of per diem hospital costs. More research is required in European settings since transferability of results is unlikely.