Outcome and resource utilization following interhospital transfer of critically ill patients

Introduction

Patients who undergo transfer to the ICU of an academic referral centre represent a group of sicker patients with increased risk for grim prognosis than those admitted directly. These patients' weight in terms of increased resource utilization is, however, less studied. This study aimed to compare the outcome and resource consumption between directly admitted patients and those transferred from a peripheral hospital to the ICU of a large tertiary-care referral centre.

Methods

A prospective observational cohort study was conducted. All consecutive patients admitted to the medical and surgical ICU from 15 September 2007 to 15 December 2007 were retained for analysis. Severity of illness by means of the Sequential Organ Failure Assessment (SOFA) score, length of stay (LOS), and outcomes were gathered per admission. Data are presented as numbers (%) or as mean ± standard deviation. All statistical tests were performed as appropriate. The level of significance was set at P < 0.05.

Results

Crude comparison of directly admitted (n = 500) versus transfer patients (n = 85) revealed that transfer patients had significantly higher severity of illness as expressed by the admission, mean, and maximum SOFA score (P = 0.042, P = 0.034, and P = 0.005), but not by the APACHE II score (P = 0.422), respectively. Transfer patients necessitated higher resource consumption as defined by the need for mechanical ventilation (P < 0.001), vasopressor therapy (P = 0.01), medical imaging (respectively, CT or MRI) (P < 0.001), urgent surgical intervention during their stay in the ICU (P < 0.001), sedative drugs (P < 0.001), and tracheostomy placement (P < 0.001) compared with directly admitted patients, whereas no significant differences were found regarding need for renal replacement therapy (P = 0.47) and blood transfusion (P = 0.41), respectively. A significant increased ICU LOS (8.6 ± 11.1 days vs. 4.9 ± 7.4 days, P < 0.01) was observed for transferred patients, whereas no difference was found for hospital LOS (23.6 ± 27.4 days vs. 24.5 ± 25.7 days, P = 0.81). When comparing both groups, those transferred from other hospitals were found to have worse outcome as demonstrated by higher ICU and inhospital mortality rates (16.5% vs. 8.6%, P = 0.03, and 29.6% vs. 14.5%, P = 0.002). Even after adjustment for severity of illness, being transferred was found to be independently associated with higher inhospital mortality (OR = 2.84, 95% CI = 1.41 to 5.72) (receiver operating characteristic = 0.87, 95% CI = 0.83 to 0.91, P < 0.001) (Hosmer and Lemeshow, chi-square, 6.27; degrees of freedom, 8; P = 0.617).

Conclusion

Patients transferred to the ICU of a tertiary-care referral centre generally consume more resources and have worse outcome as compared with directly admitted patients.