- Design
- Prospective, single-blind randomised trial
- Population
- 79 adults aged 65 or older having total hip arthroplasty for hip fracture
- Primary outcome
- Postoperative delirium within 7 days
- Effect
- 8.1% vs 12.8%; risk difference -4.7% (95% CI -18.4% to 9.0%; P = 0.71)
This single-blind trial randomised 79 patients aged 65 or older having total hip arthroplasty for hip fracture under spinal anaesthesia. An anterior iliopsoas muscle space block was given either the day before surgery or an hour before. The primary outcome was delirium within seven days.
Delirium occurred in 8.1% (3 of 37) with the early block and 12.8% (5 of 39) with the block an hour before (risk difference -4.7%, 95% CI -18.4% to 9.0%; P = 0.71). Pain at 6 hours was lower with the early block (resting 2.46 against 2.95; movement 3.24 against 3.79), but these differences did not survive correction for multiple comparisons.
The interval is wide and the trial is small, so it cannot rule out a benefit or a harm. The pain signal is exploratory. Block timing can be left to logistics and local practice for now.
- Block timing (day before or one hour before) did not clearly change delirium in this small trial.
- Do not delay surgery to arrange an early block.
- Continue delirium prevention measures: orientation, sleep, avoiding deliriogenic drugs, early mobilisation.
- Treat the early pain benefit as unproven.
Why it matters
Delirium is the outcome that matters most to families after hip fracture, and a simple change of timing was not enough to move it.
Don't overread it
A 79-patient trial that missed its primary endpoint does not show that early blocks are ineffective or that timing is irrelevant.
The statistics, in plain English
The interval for the difference runs from an 18-point reduction to a 9-point rise in delirium, so the trial neither shows equivalence nor benefit. Pain differences at 6 hours became non-significant after correcting for the many comparisons tested.
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