Objective: To identify priorities for intensive care unit (ICU) intervention and research.
Design: Analysis of a large intensive care database.
Setting: Twenty-four ICUs in the North Thames region of the United Kingdom.
Patients: All patients admitted to an ICU between January 1, 1992, and April 31, 1996, on whom data had been entered into the database. Patients who were admitted after cardiac surgery, who had burns, or were <16 yrs of age were excluded from the study, as were data from patients with a previous ICU admission within 6 mos or where ICU or hospital outcome was unknown. Data were excluded from units that had entered <300 patients into the database.
Measurements and main results: A total of 23,331 admissions with complete records were available. After exclusions, 12,762 admissions from 15 ICUs were selected for analysis. Hospital mortality was 32.5% with a mortality ratio of 1.14 (95% confidence interval 1.10 to 1.17). Nonsurvivors were older than survivors and had longer ICU stays. Patients admitted from wards had a higher mortality than patients from the operating room/recovery or the emergency department. Observed percentage mortality increased linearly with mortality predicted by Acute Physiology and Chronic Health Evaluation II, although the number of patients who died remained broadly constant across the range of predicted mortality. Twenty-seven percent of all deaths occurred after discharge from the ICU. Patients admitted after cardiopulmonary resuscitation constituted 30% of all deaths. Thirty-four percent of patients were in the ICU for >2 days, and they accounted for nearly 81% of bed days.
Conclusions: Early identification of patients at risk, both before admission and after discharge from the ICU, may allow treatment to decrease mortality. Research and resources may be best directed at patients who die, despite a relatively low predicted mortality. Although these patients are a small percentage of the low-risk admissions, they constitute a large number of ICU deaths. Many patients die after discharge from ICU and this mortality may be decreased by minimizing inappropriate early discharge to the ward, by the provision of high-dependency and step-down units, and by continuing advice and follow-up by the ICU team after the patient has been discharged. Intervention before ICU admission and support of patients after discharge from the ICU should be part of the effort to decrease mortality for ICU patients. Inadequate provision of resources for critically ill patients may result in excess intensive care mortality that is not detected with ICU outcome prediction methods.