Hospital‐wide evaluation of delirium incidence in adults under 65 years of age

Abstract

Delirium is generally perceived as an acute neuropsychiatric condition in the elderly. The incidence in adults under 65 years of age has been largely neglected, although pooled epidemiological data indicate a notable incidence.1 However, this has not yet been systematically evaluated in a large cohort. Here we show that delirium occurred in about one out of 10 adults under 65 years of age in a comprehensive sample of 18 599 patients across 35 services. Though important advances have been made in delirium prevention and treatment in the elderly, the application of those findings in adults under 65 years of age is not straightforward. The investigation of delirium incidence in younger adults is fundamental to estimate its relevance. All data in this prospective cohort study were collected at the University Hospital Zurich, Switzerland, a tertiary care center, in 2014, based on a quality-improvement initiative aiming to improve the detection and management of delirium for all hospitalized patients, the ‘Delir-Path.’2 This study was approved by the ethics committee of the Canton of Zurich (KEK-ZH-Nr. 2012-0263). A waiver of informed consent was obtained from the committee. Incidence was determined by simple logistic regressions with their respective odds ratios (OR). Please refer to Appendix S1 for more details on the inclusion criteria and the statistical analysis, and to Figure S1 for the flowchart of sample recruitment. Upon suspicion, trained nursing staff performed the Delirium Observation Screening (DOS) Scale, which reflects DSM-IV criteria. In patients with a DOS score ≥3, presence of delirium was considered, and evaluation by a physician according to the DSM-5 criteria was requested. The contents of nurses' training are described in the supplements. The cut-off score of ≥3 was chosen due to the decent sensitivity and specificity, and its high negative predictive value of almost 100% as previously demonstrated.3 Once delirium was documented, it was followed up with DOS three times daily until indication of remission. In the intensive care units (ICU), the Intensive Care Delirium Screening Checklist (ICDSC) was routinely performed three times per day. In patients with an ICDSC score of ≥4, presence of delirium was considered,4 and evaluation by a physician was requested. The overall incidence of delirium in our cohort of adults under 65 years of age was 14.5%. Delirious patients were on average older than non-delirious patients (mean 49 vs 42 years; P < 0.001) and were hospitalized considerably longer (mean 17 vs 7 days; P < 0.001). Patients developing delirium were often urgent admissions (59% vs 46%; P < 0.001, OR 1.7, 95% confidence interval [CI] 1.58–1.86), and came from other hospitals and assisted living rather than from home (76% vs 93%; P < 0.001, OR 0.23, CI 0.21–0.26). Their mortality was significantly increased (OR 41.8, CI 32.41–53.98, P < 0.001). The need for rehabilitation was much higher in patients who had delirium (23% vs 5%; P < 0.001, OR 5.47, CI 5.03–5.95). Across different ICU, the incidence ranged from 64.9% to 84.5% (P < 0.001, OR 10.85–32.38; Fig. 1). In medical services, incidence was highest in palliative care (54.0%, OR 7.24) (Figure S2). In surgical departments, rates were highest in cardiac surgery (50.1%, OR 6.87) and neurosurgery (40.5%, OR 4.38) (Figure S3). All demographic data and OR for all services can be found in Table S1 and S2, and Figure S4. In summary, the incidence of delirium in adults under 65 years of age was considerable in our cohort. As expected, the incidence of delirium in the elderly population > 65 years is generally higher than in our cohort.5 However, delirium rates in our cohort in departments of neurology, cardiac surgery, and palliative care resembled those reported in the elderly.5-7 Regarding critical care units, our findings confirm previous notions of high incidence in younger adults.8 Taken together, those findings attenuate the low-predisposition–severe-precipitator paradigm for delirium triggers.9, 10 Further, this study delineates the trajectories of the delirious patients, irrespective of age: being admitted as emergencies, hospitalized longer, and at discharge either institutionalized or deceased. Arguably, higher predisposition and vulnerability in the elderly legitimates the focus on the older population. Patients 65 years and older from this cohort had higher odds of developing delirium (OR 2.77, P < 0.001) and across all services, 31.6% developed delirium during hospitalization. Nevertheless, inclusion of adults under 65 years of age in clinical trials should be considered, because their treatment responses and outcomes might be different from those in the elderly. In conclusion, despite lower predisposition to delirium and lower incidence, our findings encourage clinical research in patients under 65 years of age. Departments with high delirium incidence rates may already promote early detection in order to improve patient care and lower costs. Nothing to declare. Appendix S1. Supplemental information to ‘Letter to the Editor: A hospital-wide evaluation of delirium incidence in adults under 65 years of age.’ Figure S1 Flowchart of sample recruitment. LOS, length of stay. Figure S2 Bar plots illustrating incidence (%) of delirium across medical services. Figure S3 Bar plots illustrating incidence (%) of delirium across surgical services. Figure S4 Forest plots illustrating odds ratios for development of delirium across all departments. Table S1 Patient Demographics, *Mean ± SD/Median – IQR; Range. Table S2 Incidence and odds for developing delirium across all departments. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

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