Cognitive Outcomes After Hip Fracture Surgery: The Association of Postoperative Delirium on Previously Cognitively Normal Older Adults

OBJECTIVES: Delirium, an acute disorder of attention and cognition, is a preventable contributor to poor outcomes in older adults including future cognitive decline. The goal of this study was to examine the cognitive impact of postoperative delirium. DESIGN, SETTING, PARTICIPANTS: A secondary analysis of the randomized clinical trial STRIDE (A Strategy to Reduce the Incidence of Postoperative Delirium in Elderly Patients) which included two hundred hip fracture repair patients was conducted. MEASUREMENTS: Cognitive changes one year after surgery were examined. Modified Clinical Dementia Rating (CDR) and postoperative delirium status were adjudicated by a consensus panel. Delirium Rating Scale-Revised-98(DRS-R-98) was used to measure delirium severity. Data were analyzed using a random-intercept linear spline model, with Mini Mental State Examination (MMSE) and dementia severity (using CDR Sum of Boxes [CDR-SB]), as outcomes. RESULTS: 36.5% of the overall cohort experienced delirium. When stratified by baseline cognitive status, delirium was associated with a faster rate of decline in MMSE and worsening in CDR-SB in cognitively unimpaired participants, but not in participants with baseline cognitive impairment. We found an estimated delirium associated change in MMSE of 1.52 points and CDR-SB of 1.22 points within one year after surgery associated with postoperative delirium after hip fracture repair in cognitively normal participants. CONCLUSIONS: This study provides evidence that postoperative delirium is associated with a faster rate of cognitive decline, particularly in cognitively unimpaired individuals. This work highlights the importance of delirium prevention and management strategies in improving long-term cognitive outcomes in older adults.