Effects of PNB Timing on Postoperative Delirium for Hip Fracture

Hip fracture is a common cause of hospitalization in older adults and is associated with substantial pain and a high risk of delirium. Peripheral nerve blocks (PNBs) can provide effective, opioid-sparing analgesia, but the relationship between the timing of PNB administration after hospital presentation and subsequent delirium is not well established. This prospective, longitudinal, dual-centre pilot study will evaluate the association between the timing of PNB administration and the development and severity of delirium in adults aged 65 years or older admitted with a hip fracture requiring surgical repair and a planned PNB. Approximately 60 patient participants will be enrolled at University Hospital and Victoria Hospital, London Health Sciences Centre. Caregiver participants will also be recruited to provide information on baseline and follow-up cognitive and functional status. Participants will receive standard clinical care; the study will not determine or alter the timing or type of PNB, surgery, analgesia, or other treatment. PNB timing will be classified as early (\<6 hours after hospital presentation), intermediate (6 to 12 hours), or late (\>12 hours). The primary outcome is new-onset delirium during hospitalization, assessed using the 4 A's Test (4AT). Delirium severity will also be evaluated using serial 4AT scores collected during the hospital stay. The investigators hypothesize that earlier PNB administration will be associated with a lower incidence and severity of delirium. Secondary and exploratory outcomes include perioperative opioid consumption, hospital length of stay, 30-day mortality, delirium burden, and functional and caregiver-reported delirium outcomes at 3 months. The study will also assess recruitment feasibility and generate preliminary estimates of delirium incidence and effect size to inform the design and sample-size calculation of a future adequately powered prospective study.