This decision is based mainly on the intensivist’s expert judgement as well as his awareness of current ICU bed availability. A until bed is then requested in the unit specified by the intensivist. All patients admitted to the MICU or HDU within 24 h of presentation at the ED between January and December 2009, and who were admitted under the following medical specialties, were eligible for inclusion: general medicine; respiratory medicine; infectious disease; gastroenterology; psychiatry;

rheumatology, allergy and immunology; medical oncology; rehabilitation medicine and geriatric medicine. Patients who would have been admitted to the MICU/HDU under the aforementioned specialties, but were admitted to other critical care units because of the unavailability of beds, were likewise included. Patients who were admitted under cardiology, neurology and other surgical specialties were excluded as these specialties manage their own ICU and the nature of intensive care required for these patients would have been different from that required for general MICU patients. Patients were classified into direct and indirect admissions. Direct admissions comprised patients admitted directly to the MICU/HDU within 24 h of presentation at the

ED. Patients who were initially admitted to the wards and subsequently transferred to the MICU/HDU within 24 h of presentation at the ED were considered indirect admissions. A previous study15 showed that the in-hospital mortality rate for indirectly admitted patients was 44% with a relative risk of 1.41. At a direct to indirect admission ratio of 1:1, confidence level of 95%, power of 80% and minimum effect size of 12.8%, the estimated minimum sample size was 480 patients. In-hospital mortality, 60-day mortality, MICU/HDU and total in-hospital length of stay were compared between the two groups. Except for deaths within 60 days of

admission, data on the independent and dependent variables as well as selected covariates were extracted from the Operations Data Store hospital administrative database, ED, MICU and HDU case notes. Sixty-day mortality was requested from the Ministry of Health, Singapore. Data extraction was performed by one trained research assistant. Data were periodically reviewed by the investigator for completeness Dacomitinib and were subjected to logic checks. Analysis Analysis was conducted with PASW Statistics Release V.18.0 (IBM, New York). Aside from baseline patient characteristics, the proportion of direct and indirect MICU/HDU admissions relative to total MICU/HDU admissions were generated using descriptive statistics. Outcomes were expressed as dichotomous variables with an MICU/HDU length of stay categorised into <2 and 2+ days, and an in-hospital length of stay categorised into <8 and 8+ days. Possible associations between an admitting unit and each outcome were explored through univariate analysis.