Partial and No Recovery from Delirium in Older Hospitalized Adults: Frequency and Baseline Risk Factors

ObjectivesTo determine the frequency and baseline risk factors for partial and no recovery from delirium in older hospitalized adults. DesignCohort study with assessment of recovery status approximately 1 and 3months after enrollment. SettingUniversity-affiliated, primary, acute-care hospital. ParticipantsMedical or surgical inpatients aged 65 and older with delirium (N=278). MeasurementsThe Mini-Mental State Examination (MMSE), Confusion Assessment Method (CAM), Delirium Index (DI), and activities of daily living (ADLs) were completed at enrollment and each follow-up. Primary outcome categories were full recovery (absence of CAM core symptoms of delirium), partial recovery (presence of 1 CAM core symptoms but not meeting criteria for delirium), no recovery (met CAM criteria for delirium), or death. Secondary outcomes were changes in MMSE, DI, and ADL scores between the baseline and last assessment. Potential risk factors included many clinical and laboratory variables. ResultsIn participants with dementia, frequencies of full, partial, and no recovery and death at first follow-up were 6.3%, 11.3%, 74.6%, and 7.7%, respectively; in participants without dementia, frequencies were 14.3%, 17%, 50.9%, and 17.9%, respectively. In participants with dementia, frequencies at the second follow-up were 7.9%, 15.1%, 57.6%, and 19.4%, respectively; in participants without dementia, frequencies were 19.2%, 20.2%, 31.7%, and 28.8%, respectively. Frequencies were similar in participants with prevalent and incident delirium and in medical and surgical participants. The DI, MMSE, and ADL scores of many participants with partial and no recovery improved. Independent baseline risk factors for delirium persistence were chart diagnosis of dementia (odds ratio (OR)=2.51, 95% confidence interval (CI)=1.38, 4.56), presence of any malignancy (OR=5.79, 95% CI=1.51, 22.19), and greater severity of delirium (OR=9.39, 95% CI=3.95, 22.35). ConclusionDelirium in many older hospitalized adults appears to be much more protracted than previously thought, especially in those with dementia, although delirium symptoms, cognition, and function improved in many participants with partial and no recovery. It may be important to monitor the longer-term course of delirium in older hospitalized adults and develop strategies to ensure full recovery.