Environmental risk factors for delirium in hospitalized older people

OBJECTIVES: To evaluate the relationship of environmental risk factors in h ospitals to changes over time in delirium symptom severity scores. DESIGN: Observational prospective clinical study with repeated measurements , several times during the first week of hospitalization and then weekly du ring hospitalization. SETTING: University-affiliated general community hospital. PARTICIPANTS: Four hundred forty-four patients age 65 and older admitted to the medical wards: 326 with delirium and 118 without delirium. Patients wi th prior cognitive impairment were oversampled. MEASUREMENTS: The severity of delirium symptoms was measured with the Delir ium Index, a scale developed and validated by our group, based on the Confu sion Assessment Method. Potential environmental risk factors assessed inclu ded isolation, hospital unit, room changes, levels of sensory stimulation, aids to orientation, and presence of medical (e.g., intravenous) or physica l restraints. RESULTS: Controlling for initial severity of delirium and patient character istics, variables significantly related to an increase in delirium severity scores included hospital unit (intensive care or long-term care unit), num ber of room changes, absence of a clock or watch, absence of reading glasse s, presence of a family member, and presence of medical or physical restrai nts. CONCLUSION: The associations of intensive care and medical and physical res traints with severity of delirium symptoms may be due to uncontrolled confo unding by indication. However, the other factors identified suggest potenti ally modifiable risk factors for symptoms of delirium in hospitalized older people.