Delirium is a risk factor for further cognitive decline in cognitively impaired hip fracture patients

Delirium is a risk factor for dementia in cognitively intact patients. Whether an episode of delirium accelerates cognitive decline in patients with known dementia, is less explored.

This is a prospective follow-up study of 287 hip fracture patients with pre-fracture cognitive impairment. During the hospitalization, the patients were screened daily for delirium using the Confusion Assessment Method. Pre-fracture cognitive impairment was defined as a score of 3.44 or higher on the pre-fracture Informant Questionnaire on Cognitive Decline in the Elderly Short Form (IQCODE-SF). At follow-up after 4-6 months, the caregivers rated cognitive changes emerging after the fracture using the IQCODE-SF, and the patients were tested with the Mini Mental State Examination (MMSE). A sub-group of the patients had a pre-fracture MMSE score which was used to calculate the yearly decline on the MMSE in patients with and without delirium.

201 of the 287 patients developed delirium in the acute phase. In linear regression analysis, delirium was a significant and independent predictor of a more prominent cognitive decline at follow-up measured by the IQCODE-SF questionnaire (p=0.002). Among patients having a pre-fracture MMSE score, the patients developing delirium had a median (IQR) yearly decline of 2.4 points (1.1-3.9), compared to 1.0 points (0-1.9) in the group without delirium (p=0.001, Mann-Whitney test).

Hip fracture patients with pre-fracture dementia run a higher risk of developing delirium. Delirium superimposed on dementia is a significant predictor of an accelerated further cognitive decline.