The Effect of Transversus Abdominis Plane Block on Pain-Related Outcomes in Kidney Transplantation: A Systematic Review with Meta-Analysis and Trial Sequential Analysis

Background/Objectives: Due to post-surgical discomfort in kidney transplant recipients and donors as well as opioids' multiple side effects, alternative analgesic methods are required in renal transplant surgeries. This study aimed to evaluate the analgesic effect of the transversus abdominis plane (TAP) block versus no-block controls in kidney transplantation patients. Methods: We conducted a meta-analysis with a trial sequential analysis (TSA) of randomized controlled trials (RCTs). We searched for relevant articles in PubMed, Scopus, and the Cochrane Library published before December 2023. Protocol registration: doi.org/10.17605/OSF.IO/PMZJ4. Results: A total of 11 RCTs were included in the meta-analysis. The TAP block group had lower pain intensity on postoperative day 1 (mean difference, MD = -0.65 [-0.88, -0.42]; p < 0.00001) than the control group. However, the heterogeneity among the included studies was considerable (I-2 = 93%). Subgroup meta-analysis and TSA revealed a significant pain reduction at 24 h postoperatively in donors (MD = -0.70 [-1.16, -0.24]; p = 0.003); heterogeneity was substantial (I-2 = 67%). The TAP block group also had lower overall morphine consumption within 24 h (MD = -4.82 [-7.87, -1.77]; p = 0.002) and cumulative 24 h morphine use (MD = -14.13 [-23.64, -4.63]; p = 0.004); however, heterogeneity was considerable (I-2 = 98% in both cases). The time to first analgesia (hours) was significantly longer in the TAP block group (MD = 5.92 h [3.63, 8.22]; p < 0.00001, n = 3). There was no significant difference between the groups in postoperative nausea and vomiting (risk ratio, RR = 0.91 [0.49, 1.71]; p = 0.78). Conclusions: TAP block can lower pain intensity and reduce morphine consumption on the first postoperative day in patients undergoing renal transplantation. Pain reduction is especially notable in the subgroup of donors, but the benefits reported are minimum and certainly not clinically relevant. Larger, well-powered RCTs are warranted to confirm these results and evaluate the effect of TAP block in the subgroup of recipients.