Cognitive impairment in hip fracture patients: timing of detection and longitudinal follow-up.

OBJECTIVES: To examine the prevalence, incidence, persistence, predictors, and outcomes of cognitive impairment after hip fracture.
DESIGN: Longitudinal cohort study.
SETTING: Eight hospitals in Baltimore, Maryland. PARTICIPANTS: Six hundred seventy-four hip fracture patients aged 65 and older living in the community before fracture. MEASUREMENT: Delirium at admission and postsurgery, Mini-Mental State Examination (MMSE) scores postsurgery, and prefracture proxy ratings of MMSE and dementia. Follow-up measures at 2 and 12 months postfracture included mortality, MMSE, physical activities of daily living (PADLs), instrumental activities of daily living (IADLs), social functioning, and the Center for Epidemiologic Studies-Depression Scale.
RESULTS: Overall, 28% had prefracture dementia or MMSE impairment, 8% had cognitive impairment first detected presurgery, 14% had impairment first detected postsurgery, and 50% were not impaired before or during hospitalization. Incident cognitive impairment was more likely in patients who were older, male, and less educated and had more prefracture PADL impairment, intertrochanteric fractures, and higher anesthesia risk ratings. Presurgery incident cases did not differ significantly from those detected postsurgery in functional outcomes or in persistence of cognitive impairment. Cognitive impairment first noted in the hospital persisted through 2 and 12 months in more than 40% of patients. Those with cognitive impairment persisting through 2 months had poorer 12-month PADLs and social functioning.
CONCLUSION: Prefracture cognitive impairment and incident cognitive impairment during hospitalization are risk factors for poor functional outcomes. Many incident cognitive problems persisted over 2 to 12 months, and per-sistence predicted later functional and social impairment.