Effect of intravenous dexamethasone on postoperative pain after spinal anaesthesia - a systematic review with meta-analysis and trial sequential analysis

There are data suggesting that intravenous dexamethasone has an effect on postoperative analgesia when given during single-shot spinal anaesthesia. However, the research literature is equivocal. We performed a systematic literature search followed by conventional meta-analysis (random effects model). We used trial sequential analysis to control for type-1 and -2 statistical errors. We also performed a leave-one-out meta-analysis for our primary outcome, the consumption of intravenous morphine in the first 24 postoperative hours. We applied the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system to rate the level of evidence. We obtained data from 1133 patients, reported in 17 trials. Reporting quality was high, with low risk of bias. Dexamethasone use was associated with a significant reduction in 24-h morphine consumption, the mean difference (95%CI) being -4.01 (-5.01 to -3.01) mg, 6 trials, 326 participants, I-2 = 0%. Trial sequential analysis showed that there was firm evidence for the primary outcome, and leave-one-out meta-analysis showed that our result was not driven by one single trial. The GRADE evaluation showed a high level of evidence, suggesting that further studies are unlikely to alter the result. The time to first analgesic request (95%CI) was significantly prolonged by 86.62 (10.62-162.62) min, I-2 = 93%, in the dexamethasone group. For other secondary outcomes including number of patients requiring rescue analgesia, or visual analogue scale pain scores, we found no evidence of a significant difference between the treatment arms. We report a high level of evidence that intravenous dexamethasone improves postoperative analgesia after spinal anaesthesia.