The ANZICS adult patient database contains information on mortality of patients staying more than 48 hours in ICUs. In the financial years 2000, 2001 and 2002, of 43,760 patients treated in intensive care for greater than 48 hours for whom complete data were available, 9476 died prior to hospital discharge. The hospital mortality rate was 22%. As we will exclude less sick patients who stay greater than 48 hours and 90-day mortality is the primary outcome measure, the study has assumed a 90-day mortality rate of 26% in the control group.