Observational study of patients admitted to intensive care units in Australia and New Zealand after interhospital transfer.

OBJECTIVE: To describe the demographics, illness categories and outcomes of adult intensive care unit patients who underwent interhospital transfer (IHT).

DESIGN: Retrospective review of data from the Australian and New Zealand Intensive Care Society Adult Patient Database (ANZICS APD), a binational intensive-care quality-assurance dataset.

PARTICIPANTS AND SETTING: 332 009 patients from 125 Australian and New Zealand adult ICUs, who were aged 16 years or older, and had a known hospital and ICU source of admission between 1 January 1994 and 31 December 2003.

RESULTS: Tertiary ICUs contributed 47.9% of patients, metropolitan 20.9%, private 16.7% and rural/regional 14.5%. Patients admitted to an ICU after IHT had more severe illness, longer hospital stay, and a higher intubation rate, mortality and rate of discharge to another hospital. Over 10 years, the proportion of IHTs increased for rural/regional (R2=0.639; P=0.006) and tertiary (R2=0.703; P=0.002) hospitals, and for the diagnoses of sepsis (R2=0.877; P<0.001) and respiratory infection (R2=0.679, P=0.003); decreased for trauma (R2=0.612; P=0.007); and was associated with fewer ICU admissions after elective surgery (Beta=-1.47; 95% CI, -2.19 to -0.74; P<0.001) and from the operating theatre (Beta=-0.78; 95% CI, -1.46 to -0.1; P=0.03). IHT was most common during July-October and on Fridays and Saturdays. There were significant variations between Australian states and territories and New Zealand.

CONCLUSIONS: Patients admitted to an ICU after IHT have significant resource implications based on their severity of illness, hospital stay and mortality, and adversely affect ICU capacity for elective and operating theatre admissions. Regional differences and temporal trends have implications for planning of ICU resources and require ongoing surveillance.