Spinal or general anesthesia? This study, using data from more than 11,000 patients and conducted by the Mayo Clinic in Rochester, Minnesota, is likely an instant classic. Care to guess the results? The study, “Spinal Compared with General Anesthesia in Contemporary Primary Total Hip Arthroplasties,” appears in the September 7, 2022, edition of The Journal of Bone and Joint Surgery.
Spinal vs General Anesthesia: 11k Patient Study Picks a Winner
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Matthew Abdel, M.D., study co-author and surgeon with the Mayo Clinic Department of Orthopedic Surgery explained the background of this study to OTW: “The specific benefits of spinal anesthesia vs. general anesthesia remain debated in the literature. Over the past several years, there has been renewed interest in studying this topic due to the large increase in the proportion of same-day discharge primary total hip arthroplasties, migration to ambulatory surgery centers, and an era where the COVID-19 pandemic continues.”
The researchers looked at 13,730 primary THAs (11,319 patients) who were treated over a 15-year period from 2001 to 2016. The study patient demographics were similar, with a mean patient age of 64 years, 51% of whom were female, and the average body mass index was 31 kg/m 2.
“The novelty of our study,” said Dr. Abdel to OTW, “is that the work was done at a single high-volume institution: Mayo Clinic Rochester. In addition, we had a nice representation in both group (58% with general anesthesia and 42% who received spinal anesthesia). Most importantly, our study included an inverse probability of treatment weighted model based on a propensity score that accounted for numerous confounding patient and operative factors.”
Regarding the last point, the use of inverse probability weighting meant that a logistic regression model was used to estimate the probability of the exposure observed for a particular person, using the predicted probability as a weight in subsequent analyses.1
“With that backdrop,” explained Dr. Abdel to OTW, “we found that patients undergoing primary THAs with spinal anesthesia had significantly lower pain scores, less oral morphine equivalents use, shorter hospital length of stays, fewer altered mental status events, and fewer unplanned ICU admissions.”
In addition, the team found no difference in the incidence of deep vein thrombosis, pulmonary embolism, 30-day readmissions, 90-day readmissions, all-cause revisions, or all-cause reoperations.
When OTW asked what it is about the spinal that doesn’t give people mental status events, Dr. Abdel stated, “With spinal anesthesia, patients get less inhalational and IV agents and less opiates since the lower extremities are numbed by the spinal anesthesia during surgery. These data favor the use of spinal anesthesia in primary THAs if deemed appropriate by the medical team.”
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This is a fascinating development. In my practice we've seen similar outcomes with the revised protocol. The key differentiator seems to be patient selection criteria. Has anyone else noticed the correlation with BMI thresholds?
Great point. I'd push back slightly on the conclusion, the sample size in the cited study is too small to draw population-level inferences. That said, the directional signal is compelling and worth a larger RCT.
We implemented a similar approach last year. Early results are promising but we're still gathering 12-month follow-up data. Happy to share our protocol if anyone is interested.
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