Intrathecal Opioid Use in Kidney Transplantation: An Observational Cohort Study.

Background: Kidney transplant is the most common transplant operation performed in the United States. Although various approaches to pain management have been described, the optimal analgesic strategy remains undefined. Specifically, the role of intrathecal opioids in this patient population has not been comprehensively evaluated.

Methods: Using a retrospective cohort design, data from kidney transplant operations at a single tertiary care medical center between August 1, 2017, and July 31, 2022, were extracted. Inverse probability of treatment weighting (IPTW) was used to assess differences in clinical outcomes based on the presence or absence of intrathecal opioid administration before surgical incision. The primary outcome was total opioid exposure expressed in milligram morphine equivalents (MME) in the first 72 hours postoperatively, with secondary outcomes including total MME (intraoperative plus postoperative MME, postoperative pain scores, and the presence of postoperative nausea/vomiting [PONV], pruritus, or adverse events).

Results: A total of 1014 kidney transplants in 1012 unique patients were included, with 411 (41%) receiving intrathecal opioids preoperatively. Hydromorphone was the intrathecal opioid used in all cases with median dose of 100 µg (interquartile range [IQR], 100, 100; range 50-200). Subjects receiving intrathecal opioids had significantly lower postoperative opioid requirements at 72 hours (30 [0-68] vs 64 [22, 120] MME), with ratio of geometric means in the IPTW analysis (ratio of geometric means 0.34, 95% confidence interval [CI], 0.26-0.43; P < .001). Similar findings were observed for total opioids (45 [30-75] vs 75 [60-90] MME; ratio of geometric means 0.58, 95% CI, 0.54-0.63; P < .001). Maximum reported pain scores in the intrathecal group were lower at 24 hours (4 [2-7] vs 7 [5, 8]; OR, 0.28; 95% CI, 0.21-0.37 for experiencing a higher pain score with intrathecal opioids, P < .001) and 72 hours (6 [4-7] vs 7 [5-8]; OR, 0.41; 95% CI, 0.31-0.54; P < .001). Patients receiving intrathecal opioids were more likely to experience PONV (225 of 411 [55%] vs 232 of 603 [38%]; OR, 2.16; 95% CI, 1.63-2.86; P < .001).

Conclusions: Intrathecal opioid administration was associated with improved pain outcomes in patients undergoing kidney transplantation, including lower opioid requirements and pain scores through 72 hours. However, this was accompanied by an increased risk of PONV.