Spinal Versus General Anesthesia for Patients Undergoing Outpatient Total Knee Arthroplasty

A National Propensity Matched Analysis of Early Postoperative Outcomes

Mark C. Kendall; Alexander D. Cohen; Stephanie Principe-Marrero; Peter Sidhom; Patricia Apruzzese; Gildasio De Oliveira

Disclosures

BMC Anesthesiol. 2021;21(226) 

In This Article

Results

A total of 353,970 patients undergoing unilateral TKA were included in the NSQIP database for 2005–2018. A total of 6,504 patients underwent outpatient TKA and 5,574 were eligible after exclusion criteria (Figure 1) Table 1 and Table 2.

Figure 1.

Flow diagram of included and excluded patients. NSQIP = National Surgical Quality Improvement; TKA = Total Knee Arthroplasty. Of these, 2,034 patients had surgery with general anesthesia and 3,540 had surgery with spinal anesthesia. A cohort of 1,962 patients who underwent TKA under general anesthesia were propensity matched with 1,962 patients who underwent TKA under spinal anesthesia. Patients in the outpatient group who had general anesthesia were younger (64.4 vs. 66.3, P < 0.001), and more likely to have a greater body mass index (32.6 vs 31.1) (P < 0.001) (Table 1). Covariates were well balanced between the propensity matched cohorts, absolute standard mean difference < 0.1 for all covariates (Table 2)

Serious adverse events rates at 72 h were not greater in patients receiving general anesthesia compared to spinal anesthesia (0.92% vs. 0.66%, P = 0.369). In contrast, minor adverse events at 72 h after surgery were greater in the general anesthesia group compared to spinal anesthesia (2.09% vs. 0.51%), P < 0.001. In addition, the incidence of any adverse events at 72 h was also greater in the general anesthesia group (2.91% vs. 1.02%), P < 0.001. Specific rates for each adverse event comparing patients who had TKAs under general anesthesia to patients who had TKAs under spinal anesthesia are presented on Table 3. Specifically, the rate of blood transfusions 72 h after surgery were lower in the spinal anesthesia group compared to the general anesthesia, false discovery adjusted rate of P = 0.0004. Relative risks for each adverse event comparing general anesthesia to spinal anesthesia in TKA outpatients are presented in Figure 2.

Figure 2.

Forest Plots illustrating the relative risks of adverse events in outpatients undergoing total knee arthroplasty comparing general anesthesia to spinal anesthesia. Abbreviations: SSI = surgical site infection; VTE = venous thromboembolism; Diamonds represent the point estimate for relative risk; line represents 95% confidence intervals

Of note, readmission rates did not significantly differ between the groups. Failure to rescue in the matched cohort also did not differ from general and spinal anesthesia, 1/20 vs 1/57, P = 0.45.

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