Adverse Events Experienced by Patients Hospitalized without Definite Medical Acuity: A Retrospective Cohort Study
Physicians often consider various nonmedical factors in hospital admission decision-making and may admit socially tenuous patients despite low-acuity medical needs. Evidence showing whether these patients are subject to the same risks of hospitalization as those considered definitely medically appropriate is limited. Our study sought to inform this risk/benefit discussion by quantifying the number of adverse events (AEs) experienced by both patient populations by using the Institute for Healthcare Improvement Global Trigger Tool methodology. We found no difference in the percentage of admissions with AEs between the two groups (27.3% vs 29.3%; risk ratio 0.93, 95% CI 0.65-1.34, P = .70) nor in AEs per 1,000-patient days (76.8 vs 70.4; incidence rate ratio = 1.09, 95% CI 0.77-1.55, P = .61). Thus, the number of AEs experienced during hospitalization does not appear to be related to the appropriateness of admission based on the level of medical acuity.
© 2020 Society of Hospital Medicine
Chart review was performed to capture patient demographics, admission characteristics, and hospitalization outcomes. We captured emergency severity index (ESI)6, a validated, reliable triage assessment score assigned by our emergency department, as a measurement of acute illness and calculated the Charlson comorbidity index (CCI)7 as a measurement of chronic comorbidity.
Identification of Adverse Events
We measured AEs by using the Institute for Healthcare Improvement Global Trigger Tool,8,9 which is estimated to identify up to 10 times more AEs than other methods, such as voluntary reporting.5 This protocol includes 28 triggers in the Cares and Medication Modules that serve as indicators that an AE may have occurred. The presence of a trigger is not necessarily an AE but a clue for further analysis. Two investigators (AS and CS) independently systematically searched for the presence of triggers within each patient chart. Trigger identification prompted in-depth analysis to confirm the occurrence of an AE and to characterize its severity by using the National Coordinating Council for Medication Error Reporting and Prevention categorization.10 An AE was coded when independent reviewers identified evidence of a preventable or nonpreventable “noxious and unintended event occurring in association with medical care.”9 By definition, any AEs identified were patient harms. Findings were reviewed weekly to ensure agreement, and discrepancies were adjudicated by a third investigator (MB).
All study data were collected by using REDCap electronic data capture tools hosted at the University of Washington.11 The University of Washington Institutional Review Board granted approval for this study.
Study Outcome and Statistical Analysis
The primary outcome was AEs per group with results calculated in three ways: AEs per 1,000 patient-days, AEs per 100 admissions, and percent of admissions with an AE. The risk ratio (RR) for the percent of admissions with an AE and the incidence rate ratio (IRR) for AEs per 1,000 patient-days were calculated for the comparison of significance.
Other data were analyzed by using Pearson’s chi square for categorical data, Student t test for normally distributed quantitative data, and Wilcoxon rank-sum (Mann–Whitney) for the length of stay (due to skew). Analyses were conducted using STATA (version 15.1, College Station, TX).
This work follows standards for reporting observational students as outlined in the STROBE statement.12
RESULTS
Patient Demographics
Both groups were predominantly white/non-Hispanic, male, and English-speaking (Table 1). More patients without definite medical acuity were covered by public insurance (78.9% vs 69.8%, P = .010) and discharged to homelessness (34.8% vs 22.6%, P = .041).
Measures of Illness
Patients considered definitely medically appropriate had lower ESI scores, indicative of more acute presentation, than those without definite medical acuity (2.73 [95% CI 2.64-2.81] vs 2.87 [95% CI 2.78-2.95], P = .026). There was no difference in CCI scores (Table 1).
Reason for Admission and Outcomes
Admissions considered definitely medically appropriate more frequently had an identified diagnosis/syndrome (66% vs 53%) or objective measurement (8.7% vs 2.7%) listed as the reason for admission, whereas patients admitted without definite medical acuity more freuqently had undifferentiated symptoms (34.7% vs 24%) or other/disposition (6% vs 1.3%) listed. The most common factors that triage physicians cited as contributing to the decision to admit patients without definite medical acuity included homelessness (34%), lack of outpatient social support (32%), and substance use disorder (25%). More details are available in Appendix Tables 1 and 2.
