Vital sign abnormalities as predictors of clinical deterioration in subacute care patients: A prospective case-time-control study

Abstract

Emergency interhospital transfers from inpatient subacute care to acute care occur in 8% to 17.4% of admitted patients and are associated with high rates of acute care readmission and in-hospital mortality. Serious adverse events in subacute care (rapid response team or cardiac arrest team calls) and increased nursing surveillance are the strongest known predictors of emergency interhospital transfer from subacute to acute care hospitals. However, the epidemiology of clinical deterioration across sectors of care, and specifically in subacute care is not well understood. To explore the trajectory of clinical deterioration in patients who did and did not have an emergency interhospital transfer from subacute to acute care; and develop an internally validated predictive model to identify the role of vital sign abnormalities in predicting these emergency interhospital transfers. This prospective, exploratory cohort study is a subanalysis of data derived from a larger case-time-control study. Twenty-two wards of eight subacute care hospitals in five major health services in Victoria, Australia. All subacute care hospitals were geographically separate from their health services' acute care hospitals. All patients with an emergency transfer from inpatient rehabilitation or geriatric evaluation and management unit to an acute care hospital within the same health service were included. Patients receiving palliative care were excluded. Study data were collected between 22 August 2015 and 30 October 2016 by medical record audit. The Cochran-Mantel-Haenszel test and bivariate logistic regression analysis were used to compare cases with controls and to account for health service clustering effect. Data were collected on 603 transfers (557 patients) and 1160 controls. Adjusted for health service, ≥2 vital sign abnormalities in subacute care (adjusted odds ratio=8.81, 95% confidence intervals:6.36-12.19, p<0.001) and serious adverse events during the first acute care admission (adjusted odds ratio=1.28, 95% confidence intervals:1.08-1.99, p=0.015) were the clinical factors associated with increased risk of emergency interhospital transfer. An internally validated predictive model showed that vital sign abnormalities can fairly predict emergency interhospital transfers from subacute to acute care hospitals. Serious adverse events in acute care should be a key consideration in decisions about the location of subacute care delivery. During subacute care, 15.7% of cases had vital signs fulfilling organisational rapid response team activation criteria, yet missed rapid response team activations were common suggesting that further consideration of the criteria and strategies to optimise recognition and response to clinical deterioration in subacute care are needed.