Association of peripheral nerve blocks with postoperative outcomes in ambulatory shoulder surgery patients: a single-centre matched-cohort study

Abstract

Purpose: Regional anesthesia may have immediate postoperative advantages compared with general anesthesia, but its impact on post-discharge outcomes is poorly described. Our objective was to measure the association between regional anesthesia and outcomes after ambulatory shoulder surgery. Methods: We conducted a historical cohort study at The Ottawa Hospital. Adults ≥ 18 yr old having elective ambulatory shoulder surgery from January 1, 2011 to December 31, 2016 were included. Using one-to-many coarsened exact matching (CEM) to adjust for potential confounders, we matched peripheral nerve block (PNB) patients to those without a PNB. Within the matched cohort, we assessed whether PNBs were associated with our primary composite outcomes, comprising unplanned admissions, emergency department visits, readmissions, or death within 30 days of surgery. Results: There were 1,623 patients who met the inclusion criteria; PNBs were placed in 1,382 (85.2%) patients. CEM matched 211 patients who did not receive a PNB to 950 patients with similar characteristics who did receive a PNB (n = 1,161; 71.5% of total cohort). In patients who received a PNB compared with those who had no PNB, there was no difference in risk of composite outcome (relative risk, 1.58; 95% confidence interval [CI], 0.83 to 3.01), or hospital costs (ratio of means 0.73; 95% CI, 0.21 to 2.49). Conclusion: Peripheral nerve blocks in ambulatory shoulder surgery were not associated with a significant difference in a composite of adverse postoperative outcomes. Nevertheless, given the lower than expected incidence and moderate effect size associating PNBs with post-discharge events, future large prospective trials are needed to assess post-discharge outcomes. Trial registration: www.clinicaltrials.gov (NCT03309644). Registered 13 October 2017.