Anesthesia and postoperative delirium in older adults undergoing hip surgery

OBJECTIVES: To examine the effects of general anesthesia on the risk of incident postoperative delirium in older adults undergoing hip surgery. DESIGN: Secondary analysis of haloperidol prophylaxis for delirium clinical trial data. Predefined risk factors for delirium were assessed prior to surgery. Primary outcome was postoperative delirium. Study outcome was compared across patient groups who received either general or regional anesthesia, and for individuals receiving various perioperative medications (benzodiazepines, anti-cholinergics, and opioids), using multivariable logistic regression after controlling for potential confounders. Subgroup analyses based on baseline cognitive impairment and delirium risk were also undertaken. SETTING: Large medical school-affiliated general hospital in Alkmaar, the Netherlands. PARTICIPANTS: Five hundred twenty-six adults aged 70 and older undergoing hip surgery. MEASUREMENTS: The primary outcome was the incidence of postoperative delirium (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, and Confusion Assessment Method criteria). RESULTS: Sixty participants (11.4%) had incident postoperative delirium. One hundred eighty-nine (35.9%) received general anesthesia, 18 (9.5%) of whom developed postoperative delirium, and 337 (64.1%) received regional anesthesia, 42 (12.5%) of whom developed postoperative delirium (adjusted odds ratio = 0.81, 95% confidence interval = 0.43-1.52, P=.51). Results were stratified for baseline cognitive impairment, age, acute admission, perioperative medication and other delirium risk factors. Delirium was not independently associated with specific drugs or the medication classes opioids, benzodiazepines, and anticholinergics. CONCLUSION: General anesthesia has no distinct effect on incident postoperative delirium in older adults undergoing hip surgery. This also holds for individuals suffering from cognitive impairment or who are otherwise at risk for postoperative delirium. Perioperative use of narcotics, benzodiazepines, and anticholinergic agents was not associated with incident delirium in this cohort of older adults undergoing hip surgery