Use of neuraxial anesthesia decreases the development of surgical site infections compared with general anesthesia after total joint arthroplasty, a meta-analysis has found. These findings may help support the use of neuraxial techniques in enhanced recovery after surgery (ERAS) pathways.
“There are some smaller, observational studies suggesting that if you use spinal or epidural analgesia, it can lower the risk of surgical site infections,” said Christopher L. Wu, MD, professor of anesthesiology and critical care medicine at Johns Hopkins School of Medicine, in Baltimore.
“Our goal was to look at all the relevant studies in the literature and see if this was, indeed, the case. One of the reasons related to this is that in our own enhanced recovery pathway, we are trying to minimize the incidence of surgical site infections [SSIs].”
To help clarify this potential association, the investigators used PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines to search a variety of databases for all relevant studies (1990-2015) that reported on the association between anesthetic technique and SSIs after total knee or hip arthroplasty.
The meta-analysis was conducted to estimate both the pooled unadjusted odds ratio (OR) and the adjusted OR (aOR), using a random effects model. Subgroup analyses and meta-regression were performed to examine potential sources of heterogeneity and bias.
Reduced Infections in Knees, Not Hips
As Dr. Wu reported at the 2016 annual meeting of the American Society of Regional Anesthesia and Pain Medicine (abstract 1394), out of an initial pool of 435 records, nine studies from the United States; two from South Korea; and one each from Canada, Denmark and Taiwan met the inclusion criteria. A total of 362,029 patients were included.
The use of neuraxial anesthesia was associated with a significant reduction in the incidence of postoperative SSI compared with general anesthesia for all arthroplasties based on unadjusted data (OR, 0.77; 95% CI, 0.70-0.86;P<0.001) and adjusted data (aOR, 0.84; 95% CI, 0.76-0.92; P<0.001).
“The other interesting part of this is that when we divide the groups between hip and knee arthroplasties, we saw a statistically significant reduction in surgical site infections in knees, but not hips,” Dr. Wu said in an interview with Anesthesiology News. “We can’t really explain why this is, though it may be a study design issue.”
Indeed, the subgroup analyses yielded statistically significant reductions in the incidence of postoperative SSIs for knee arthroplasty (OR, 0.75; 95% CI, 0.68-0.84; P<0.001; aOR, 0.85; 95% CI, 0.79-0.92; P<0.001), but not hip arthroplasty (OR, 0.79; 95% CI, 0.65-0.95; P=0.02; aOR, 0.84; 95% CI, 0.71-1.00; P=0.057).
“We feel that it’s pretty strong evidence,” Dr. Wu noted. “And even though hip arthroplasty did not reach statistical significance, the P value was 0.057.”
Limitations of the Study
Dr. Wu recognized that the meta-analysis was not without its limitations, including the fact that all included trials were retrospective; variability between trials in terms of neuraxial technique and definition of an SSI; unknown influence of adjusted versus unadjusted data; and an unclear central mechanism for the prevention of SSIs.
Nevertheless, sensitivity analysis did not result in evidence of significant publication bias. In addition, the robustness of the included data was assessed by sequentially removing individual studies and reassessing the remaining data sets. This did not lead to significant changes in the resulting effect size.
In light of these findings, Dr. Wu was encouraged by the prospect of including neuraxial analgesia in an ERAS pathway for total joint arthroplasty. “Certainly there are different ways to design ERAS pathways, with many goals. One of our goals is to preserve joint function and decrease surgical site infections.” He and his colleagues have had previous success meeting these goals: Implementation of an ERAS pathway for colorectal surgery saw an SSI drop from approximately 15% to 5%.
Although the researchers were encouraged by the findings, Dr. Wu recognized that prospective randomized trials will go a long way toward clarifying the issue. “Even with these results, the findings are never foolproof,” he said. “I think people have to practice anesthesiology to the best of their situation. So while we may perform neuraxial anesthesia, it may make more sense to use general anesthesia in a different setting. There’s no one right way to deliver quality patient care.”
Findings Support Regional Anesthesia
Stuart A. Grant, MB, ChB, agreed with that sentiment, noting that general anesthesia is still common in total joint replacement surgery. “Here, we perform more than 90% of our joint replacements with a spinal anesthetic,” said Dr. Grant, professor of anesthesiology at Duke University School of Medicine, in Durham, N.C. “Nevertheless, there are still loads of centers across the country where general anesthesia is the preferred anesthetic technique, perhaps because of the risk of less bleeding.
“Still, this analysis represents more evidence to add to previous work, even if it flies in the face of typical clinical practice,” he added. “And any time you can add more supporting data, the evidence will continue to grow, and people will realize the benefits of regional anesthesia in total joint arthroplasty.”
Such evidence was in abundance at the annual meeting, particularly a study from New York City’s Hospital for Special Surgery that garnered a Best of Meeting Award (abstract 1623). In that study, Stavros Memtsoudis, MD, and his colleagues examined the influence of peripheral nerve blocks (PNBs) on a variety of perioperative outcomes in hip and knee arthroplasty.
The investigators conducted a retrospective cohort study using data from 1,062,152 such patients from the national Premier Perspective database (2006-2013). Multilevel multivariate logistic regression models were used to determine the association between PNB use and outcomes. They found that although only 17.9% of patients received a PNB, there was a marked increase in its prevalence among knee arthroplasty patients (15.2% in 2006; 24.5% in 2013).
Most telling was the fact that PNB was significantly associated with lower odds for almost all complications, including cardiac (both procedures), pulmonary (both procedures), gastrointestinal (both procedures), renal (hip only), infections, wounds, inpatient falls (hip only), transfusions (hip only), admission to the ICU, opioid consumption and length of stay. Cost of hospitalization also significantly favored PNBs among hip arthroplasty patients.
The investigators concluded that given its relatively low utilization nationwide, wider implementation of regional anesthetic techniques has the potential to significantly improve medical and economic perioperative outcomes.