Unplanned early readmission to the intensive care unit: a case-control study of patient, intensive care and ward-related factors

The purpose of this study was to identify patient, intensive care and ward-based risk factors for early, unplanned readmission to the intensive care unit. A five-year retrospective case-control study at a tertiary referral teaching hospital of 205 cases readmitted within 72 hours of intensive care unit discharge and 205 controls matched for admission diagnosis and severity of illness was conducted. The rate of unplanned readmissions was 3.1% and cases had significantly higher overall mortality than control patients (odds ratio [OR] 4.7, 95% confidence interval [CI] 2.1 to 10.7). New onset respiratory compromise and sepsis were the most common cause of readmission. Independent risk factors for readmission were chronic respiratory disease (OR 3.7, 95% CI 1.2 to 12, P=0.029), pre-existing anxiety/depression (OR 3.3, 95% CI 1.7 to 6.6, P < 0.001), international normalised ratio >1.3 (OR 2.3, 95% CI 1.1 to 4.9, P=0.024), immobility (OR 2.3, 95% CI 1.4 to 3.6, P=0.001), nasogastric nutrition (OR 2.0, 95% CI 1.0 to 4.0, P=0.041), a white cell count >15 x 10(9)/l (OR 2.0, 95% CI 1.2 to 3.4, P=0.012) and non-weekend intensive care unit discharge (OR 1.9, 95% CI 1.1 to 3.5, P=0.029). Physiological derangement on the ward (OR 26, 95% CI 8.0 to 81, P < 0.001) strongly predicted readmission, although only 20% of patients meeting medical emergency team criteria had a medical emergency team call made. Risk of readmission is associated with both patient and intensive care factors. Physiological derangement on the ward predicts intensive care unit readmission, however; clinical response to this appears suboptimal.