Provider variability in the intraoperative use of neuromuscular blocking agents: A retrospective multicentre cohort study

To assess variability in the intraoperative use of non-depolarising neuromuscular blocking agents (NMBAs) across individual anaesthesia providers, surgeons and hospitals. Retrospective observational cohort study. Two major tertiary referral centres, Boston, Massachusetts, USA. 265 537 adult participants undergoing non-cardiac surgery between October 2005 and September 2017. We analysed the variances in NMBA use across 958 anaesthesia and 623 surgical providers, across anaesthesia provider types (anaesthesia residents, certified registered nurse anaesthetists, attendings) and across hospitals using multivariable-adjusted mixed effects logistic regression. Intraclass correlations (ICC) were calculated to further quantify the variability in NMBA use that was unexplained by other covariates. Procedure-specific subgroup analyses were performed. NMBAs were used in 183 242 (69%) surgical cases. Variances in NMBA use were significantly higher among individual surgeons than among anaesthesia providers (variance 1.32 (95% CI 1.06 to 1.60) vs 0.24 (95% CI 0.19 to 0.28), p<0.001). Procedure-specific subgroup analysis of hernia repairs, spine surgeries and mastectomies confirmed our findings: the total variance in NMBA use that was unexplained by the covariate model was higher for surgeons versus anaesthesia providers (ICC 37.0% vs 13.0%, 69.7% vs 25.5%, 69.8% vs 19.5%, respectively; p<0.001). Variances in NMBA use were also partially explained by the anaesthesia provider’s hospital network (Massachusetts General Hospital: variance 0.35 (95% CI 0.27 to 0.43) vs Beth Israel Deaconess Medical Center: 0.15 (95% CI 0.12 to 0.19); p<0.001). Across provider types, surgeons showed the highest variance, and anaesthesia residents showed the lowest variance in NMBA use. There is wide variability across individual surgeons and anaesthesia providers and institutions in the use of NMBAs, which could not sufficiently be explained by a large number of patient-related and procedure-related characteristics, but may instead be driven by preference. Surgeons may have a stronger influence on a key aspect of anaesthesia management than anticipated.