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Effects of ICU Admission Delay on Patient Outcomes
Abstract & Commentary
By David J. Pierson, MD Professor, Pulmonary and Critical Care Medicine, Harborview Medical Center, University of Washington, Seattle. This article originally appeared in the May 2011 issue of Critical Care Alert. It was peer reviewed by William Thompson, MD. Dr. Thompson is Associate Professor of Medicine, University of Washington, Seattle. Drs. Pierson and Thompson report no financial relationships relevant to this field of study.
Synopsis: In a hospital with high ICU bed occupancy, delays in transferring critically ill patients from the emergency department or general wards to the ICU were associated with increased mortality in comparison with immediate transfer to an ICU bed, and this increased mortality was incrementally greater with increasing delay.
Source: Cardoso LTQ, et al. Impact of delayed admission to intensive care units on mortality of critically ill patients: A cohort study. Critical Care 2011;15:R28.
Cardoso and colleagues at University Hospital in Londrina, Brazil, prospectively studied all patients who were admitted to their 17-bed, closed, general adult ICU during a 12-month period. In addition to demographic and diagnostic information and severity of illness as assessed by APACHE II and SOFA scores, the authors classified the patients according to whether they could be moved immediately to the unit once the decision to do so had been made (no transfer delay), or had to wait in a short-stay unit of the emergency department or on the general hospital ward for an ICU bed to become available (transfer delay). In the latter group, they quantified the duration of the delay prior to physical transfer to the ICU and assessed illness severity both at the time of the initial ICU admission decision and at the time of actual admission to the unit. Board-certified intensivists made the decision to admit to the ICU and participated as consultants in the care of all patients until an ICU bed became available; during this time the patients were cared for by the regular ward staff. Patients were followed until hospital discharge and both therapeutic interventions and outcomes were recorded.
During the 1-year study period, there were 401 initial admissions of adult patients to the ICU (58 patients/month) whose transfer to the unit occurred within 72 hours and who remained for at least 24 hours in the ICU. Mean ICU occupancy during this period was 97.3%. Of the 401 study patients, 125 (31%) were moved into the ICU immediately and 276 (69%) experienced a delay before a bed became available. The duration of the delay ranged from 2.3 to 67.2 hours, with median delay 17.8 hours (interquartile range, 7.6-31.2 hours). Sixty-two percent of the patients received mechanical ventilation, and 55% had infusions of vasoactive drugs, with no differences between the two groups.
Patients with ICU admission delay had more comorbidities and were more likely to have sepsis as the admission diagnosis; otherwise they were similar in all aspects examined, including severity of illness at the time of the ICU admission decision. Both the APACHE II and SOFA scores of the patients with ICU transfer delay increased significantly between the time of ICU admission and actual transfer. ICU mortality rates were significantly higher in patients with transfer delay (P = 0.002), and increased progressively with the duration of the delay from 38% in patients with immediate ICU transfer to 57% in those whose transfer was delayed more than 24 hours. Each hour of waiting was independently associated with a 1.5% increased risk of ICU death (hazard ratio, 1.015; 95% CI, 1.006-1.023; P = 0.001). The authors calculated the fraction of mortality risk attributable to ICU delay to be 30% (95% CI, 11.2% – 44.8%).
This study adds to a number of previous investigations showing that outcomes are better when patients who have been identified as critically ill can be moved immediately into an ICU for their care. For example, Chaflin and colleagues showed that a delay of more than 6 hours in transferring patients from the emergency department to the ICU was associated with increased ICU and hospital mortality as well as with increased lengths of stay.1 For patients who became critically ill on the general wards, warranting transfer to the ICU, Young et al found a 3.5-fold higher unadjusted mortality rate in those whose transfer was delayed for more than 4 hours.2 One strength of the current investigation is that all ICU admissions were studied in a unit in which the majority of patients experienced a delay prior to arrival, resulting in a large number of delayed transfers and permitting the investigators to determine the sequential effects of increasing delays on mortality.
When the ICU is full, newly arriving critically ill patients typically have to wait elsewhere in the hospital in the emergency department, in some holding area, or on the general ward until a bed becomes available. The incidence of this problem varies widely but it has been reported to occur in all areas of the world. According to Cardoso et al, delays because of ICU bed unavailability are particularly problematic in Latin America and its occurrence in more than two-thirds of the patients admitted to their ICU during the course of one year does seem to be a lot. Still, the lesson of this study is important wherever ICU practice takes place. Well more than half of their patients received mechanical ventilation and/or intravenous pressors on the ward in many cases with ward staff delivering and monitoring them. Maintenance of state-of-the-art care is a challenge under such circumstances, and the fact that the patients actually became more severely ill while awaiting an ICU bed as indicated by APACHE II and SOFA scores should come as no surprise.
If you build it, they will come. This has certainly been the experience at my institution, a regional trauma center where over the last 20 years the number of ICU beds has gradually increased from 37 to more than 90, without a notable change in either patient acuity or the perennially high occupancy rate of our ICUs. Like many if not most hospitals, we still experience delays in the admission or transfer of critically ill patients to the units because of bed unavailability. Hospitals in the United States generally have more ICU beds as a proportion of total acute inpatient beds than is the case elsewhere in the world. Nonetheless, much of the data supporting the concept that delayed ICU admission worsens patient outcomes come from this country. Clearly, one of the central dilemmas in the economic and political aspects of health care is the fact that ICU care which accounts for a very large proportion of total health care expenditures improves survival once patients are identified as being critically ill. The current study cannot help but add fuel to the fire of this dilemma.
1. Chaflin DB, et al, DELAY-ED Study Group. Impact of delayed transfer of critically ill patients from the emergency department to the intensive care unit. Crit Care Med 2007;35:1477-1483.
2. Young MP, et al. Inpatient transfers to the intensive care unit: Delays are associated with increased mortality and morbidity. J Gen Intern Med 2003;18:77-83.