The burden of mental illness is substantial, accounting for between 3 and 16% of total expenditure on health across OECD countries. Severe disorders such as schizophrenia and bipolar disorder are among the top ten causes of years lost due to disability worldwide (WHO, 2008b).

Mental health care has become a policy priority in many OECD countries, coinciding with dramatic changes in the delivery of mental health services. Starting in the 1970s with de-institutionalisation and the development of modern psychiatric drugs, care has shifted from large psychiatric hospitals towards community-based integrated care involving a multidisciplinary team. Preventive and rehabilitative care and social integration have also been emphasised more than previously. Paradoxically, these shifts have made it harder to track mental health care at the population level, as few countries have a health information infrastructure suitable for following patients across a variety of delivery settings.

Patients with severe mental disorders still receive specialised care at hospitals but if appropriate and co-ordinated follow-up is provided after discharges, patients are not usually re-admitted to hospital within 30 days. A high rate of unplanned re-admissions is therefore an indicator of the quality of several dimensions of the mental health system. As part of monitoring quality of mental health care, unplanned 30 day hospital re-admission rates are used in organisations in different countries such as the Canadian Institute for Health Information, the Care Quality Commission in the United Kingdom and the National Mental Health Performance Monitoring System in the United States.

Re-admission rates for schizophrenia vary a lot across countries, with Nordic countries and Poland at the higher end, and the Slovak Republic and the United Kingdom at the lower end (Figure 5.7.1). Re-admission rates for bipolar disorders are also highest in Poland and in Nordic countries (Figure 5.7.2). Most countries have similar rates for men and women for both mental disorders.

Mental health care systems have been developing new organisational and delivery models over the past few decades. Some countries, such as Italy, Norway and the United Kingdom, use community-based "crisis teams" to stabilise patients on an outpatient basis, while Canada and the United States also emphasise community mental health care delivery. Other countries, such as Denmark and Finland, use interval care protocols to place unstable patients in hospital for short periods. Countries such as Denmark are also proactive in identifying patients in need of care through outreach teams following discharges, possibly leading to high re-admissions. A further development is a more patient-centred approach in countries such as Canada and the United Kingdom, involving patients in care and service plan development. These developments may also have some implications on re-admission rates and make it more complex to identify those re-admissions that are truly unplanned.

Unplanned re-admission is only one measure of the quality and performance of mental health care systems, and further indicators in domains such as treatment, care continuity, co-ordination and outcomes are needed for a better and more complete understanding of the performance of mental health care systems across countries.