Intrathecal morphine is standard for analgesia after caesarean delivery but causes pruritus and requires monitoring. This randomised, double-blind, placebo-controlled trial compared bilateral lateral quadratus lumborum block with 20 mL of 0.5% ropivacaine, 100 μg intrathecal morphine with a sham block, or both together, in women undergoing caesarean delivery under spinal anaesthesia. The primary outcome was the QoR-40 quality-of-recovery score at 24 hours, with significance set at P<0.017 for three-group comparison.
With 58 women analysed, non-inferiority of the block against intrathecal morphine on QoR-40 was inconclusive (mean difference -0.9, 90% CI -0.9 to 13.5). On pain, the block reduced resting pain at six hours compared with morphine (mean difference 2.9). Adding the block to morphine reduced resting pain at six hours by 3.3, coughing pain at six hours by 3.0, and worst pain at 24 hours by 1.8. Oxycodone consumption and nausea did not differ. Pruritus was commoner where a block was used, though mostly mild.
Fifty-eight patients across three arms is a small trial and the authors say larger ones are needed. The signal worth carrying is that adding the block to intrathecal morphine improved early pain, which suggests the two act complementarily rather than interchangeably.
- Non-inferiority for quality of recovery at 24 hours was inconclusive
- Block reduced resting pain at six hours vs morphine (difference 2.9)
- Block added to morphine improved resting, coughing and 24-hour worst pain
- Only 58 women across three arms — hypothesis-generating
The statistics, in plain English
An inconclusive non-inferiority result means the trial could neither show the block was as good as morphine nor that it was worse — the interval, -0.9 to 13.5, was simply too wide for either conclusion, which is what happens when a non-inferiority design is underpowered. The significance threshold was tightened to 0.017 because three groups were compared, which is the correct handling of multiple comparisons and worth noting since many small trials omit it.
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