LAUSR

STUDY OBJECTIVE Due to conflicting results published in the literature regarding the analgesic superiority between the paravertebral block and the PECS block, the study objective is to determine which one should be the first line analgesic treatment after radical mastectomy. DESIGN Systematic review, meta-analysis and trial sequential analysis. SETTING Operating room, postoperative recovery area and ward, up to 24 postoperative hours. PATIENTS Patients scheduled for radical mastectomy under general anaesthesia. INTERVENTIONS We searched five electronic databases for randomized controlled trials comparing any PECS block with a paravertebral block. MEASUREMENTS The primary outcome was rest pain score (0-10) at 2 postoperative hours, analyzed according to the combination with axillary dissection or not, to account for heterogeneity. Secondary outcomes included rest pain scores, cumulative intravenous morphine equivalents consumption and rate of postoperative nausea and vomiting at 24 postoperative hours. MAIN RESULTS Eight trials including 388 patients were identified. Rest pain scores at 2 postoperative hours were decreased in the PECS block group, with a mean difference (95%CI) of -0.4 (-0.7 to -0.1), I2 = 68%, p = 0.01, and a significant subgroup difference observed between radical mastectomy with (mean difference [95%CI]: 0.0 [-0.2 to 0.2], I2 = 0%, p = 1.00), or without axillary dissection (mean difference [95%CI]: -0.7 [-1.1 to -0.4], I2 = 40%, p < 0.001; p for subgroup difference < 0.001). All secondary pain-related outcomes were similar between groups. The overall quality of evidence was low. CONCLUSIONS There is low quality evidence that a PECS block provides marginal postoperative analgesic benefit after radical mastectomy at 2 postoperative hours only, when compared with a paravertebral block, and not beyond. Clinical trial number: PROSPERO - registration number: CRD42019131555.