Modifiable factors associated with postoperative delirium after hip fracture repair: An age-stratified retrospective cohort study

BACKGROUNDPostoperative delirium in hip fracture patients is common and is associated with substantial morbidity and consumption of resources.OBJECTIVEUsing data from the USA, we aimed to examine the relationship between postoperative delirium and (modifiable) peri-operative factors mentioned in the American Geriatrics Society Best Practice Statement on Postoperative Delirium in Older Adults, stratified by 'young old' (<80 years) and 'old-old' (≥80 years) categories.DESIGNRetrospective cohort study from 2006 to 2016.SETTINGPopulation-based claims data from the USA.PARTICIPANTSPatients undergoing 505 152 hip fracture repairs between 2006 and 2016 as recorded in the Premier Healthcare Database.MAIN OUTCOMES AND MEASURESThe main outcome was postoperative delirium; modifiable factors of interest were peri-operative opioid use (high, medium or low; <25th, 25 to 75th or >75th percentile of oral morphine equivalents), anaesthesia type (general, neuraxial, both), use of benzodiazepines (long acting, short acting, both), pethidine, nonbenzodiazepine hypnotics, ketamine, corticosteroids and gabapentinoids. Multilevel models assessed associations between these factors and postoperative delirium, in the full cohort, and separately in those aged less than 80 and at least 80 years. Odds ratios (ORs) and Bonferroni-adjusted 95% confidence intervals (95% CIs) are reported.RESULTSOverall, postoperative delirium incidence was 15.7% (n = 79 547). After adjustment for relevant covariates, the use of long-acting (OR 1.82, CI 1.74 to 1.89) and combined short and long-acting benzodiazepines (OR 1.56, CI 1.48 to 1.63) and ketamine (OR 1.09, CI 1.03 to 1.15), in particular, was associated with increased odds for postoperative delirium, while neuraxial anaesthesia (OR 0.91 CI 0.85 to 0.98) and opioid use (OR 0.95, CI 0.92 to 0.98 and OR 0.88, CI 0.84 to 0.92 for medium and high dose compared with low dose) were associated with lower odds; all P < 0.05. When analysing data separately by age group, effects of benzodiazepines persisted, while opioid use was only relevant in those aged less than 80 years.CONCLUSIONWe identified modifiable factors associated with postoperative delirium incidence among patients undergoing hip fracture repair surgery.