Delirium during acute illness in nursing home residents

To ascertain the incidence of delirium during acute illness in nursing home residents, describe the timing of delirium after acute illness onset, describe risk factors for delirium, and explore the relationship between delirium and complications of acute illness.

Prospective observational cohort study.

Three nursing homes in metropolitan New York.

Individuals who were expected to remain in the nursing home for at least 2 months, who, as part of a parent study, were receiving opioids, antidepressants, or antipsychotics on a routine basis, and who did not have an acute medical illness at the time of screening. Acute illness surveillance was performed twice weekly through communication with nursing home nursing staff and medical providers using established clinical criteria for incipient cases.

We followed patients for 14 days after illness onset, and, if applicable, an additional 14 days each after hospital admission and hospital discharge. Delirium was assessed 3 times weekly using the Confusion Assessment Method (CAM). Physical function decline was calculated using change in the Minimum Data Set Activities of Daily Living Scale (MDS-ADL) and cognitive function decline using change in the Minimum Data Set Cognitive performance scale (MDS-CPS). Falls were ascertained by record review.

Among 136 nursing home patients followed for a mean of 11.7 months, 78 experienced 232 acute illnesses, of which 162 (71%) were managed in the nursing home. The most common diagnoses were urinary tract infection (20%), cellulitis (15%), and lower respiratory tract infection (9%). Subjects experienced delirium during 41 (17.7%) of 232 acute illnesses. Female sex was associated with a greater risk of delirium (odds ratio 2.59; 95% confidence interval [CI] 1.04-6.43) but there were no other risk factors identified. Delirium was a risk factor for cognitive function decline (odds ratio 4.59; 95% CI 1.99-10.59; P = .0004), but not ADL function decline or falling.

Delirium occurred frequently as a complication of acute illness in the nursing home, and was a risk factor for cognitive function decline. This finding supports the rationale to target individuals at the onset of an acute medical problem in the design of interventions to prevent delirium in the nursing home setting.