BACKGROUND Case management, particularly in intensive form, has been widely introduced for the treatment of severe mental illness. However, the optimal intensity of case management has not been determined.
AIMS We aimed to assess whether intensive case management (small case load) reduces hospitalisation and costs compared with standard case management.
METHOD Development and rationale of a large randomised controlled trial comparing intensive case management (case load per worker < or = 15 patients) with standard case management (case load 30-35 patients).
RESULTS Two-year outcome data will be obtained on patients representative of the seriously mentally ill in inner-city mental health services.
CONCLUSIONS The study planned with 700 patients should be sufficient to detect small differences in the readmission of patients to hospital (10%), the number of days spent in hospital over a two-year period (10 days) and the average weekly cost of care per patient. The sample is large enough to compare the cost-effectiveness of intensive and standard case management in mild and severe disability and in people of African Caribbean origin and White Caucasians.