Risk of pre- and post-operative delirium and the delirium elderly at risk (DEAR) tool in hip fracture patients

Background and Purpose Delirium is common after hip fracture. Previous work has shown that a simple delirium risk factor tool, the Delirium Elderly At Risk instrument (DEAR), has a high inter-rater reliability in this population. Little research has looked at the ability of risk factor screening tools to identify patients at high risk of pre-operative delirium. This study investigates the ability of the DEAR to identify patients at high risk of pre-operative delirium, as well as reporting its performance in a post-operative validation sample. Associations between delirium risk factors and pre-operative delirium are explored. Methods This prospective cohort study took place on an orthopedic inpatient service at a University-affiliated tertiary care hospital. Patients aged 65 and older who were admitted for surgical repair of hip fracture (N = 283) were assessed pre-operatively for 5 delirium risk factors (cognitive impairment, sensory impairment, functional dependence, substance use, age) using the DEAR. Patients were assessed for delirium using the Mini-Mental State Examination and the Confusion Assessment Method pre-operatively and on post-operative days 1, 3 and 5. Characteristics of patients who developed delirium were compared with the characteristics of those who did not. Results Delirium was present in 58% (95% CI = 52-63%) of patients pre-operatively and 42% (95% CI = 36-48%) post-operatively. Individually, sensory impairment ( χ2 = 21.7, p = .0001), functional dependence ( χ2 = 24.1, p = .0001), cognitive impairment ( χ2 = 55.5, p = .0001) and substance use ( χ2 = 7.5, p = .007) were significantly associated with pre-operative delirium, as was wait-time for surgery (t = 3.1, p = .003) and length of stay (t = 2.8, p =.03). In multivariate modeling, the strongest association with pre-operative delirium was cognitive impairment. Conclusions The DEAR, a simple, delirium risk factor screening tool, can be used to identify hip fracture patients at risk of both pre-operative and post-operative delirium, which may allow targeted implementation of delirium prevention strategies.