Add-on vancomycin of little help for surgical prophylaxis in arthroplasty

Adding vancomycin to cefazolin does not appear to confer significant benefits for the prevention of surgical site infections following arthroplasty in patients without known methicillin-resistant Staphylococcus aureus (MRSA) colonization, according to the results of the ASAP trial.

ASAP included 4,239 patients without known MRSA colonization who were scheduled to undergo arthroplasty. These patients were randomly assigned to receive either 1.5 g of vancomycin or normal saline placebo in addition to cefazolin prophylaxis.

The primary outcome of surgical-site infection within 90 days after surgery was evaluated in 4,113 patients included in the modified intention-to-treat population. Of these patients, 2,233 were undergoing knee arthroplasty, 1,850 were undergoing hip arthroplasty, and 30 were undergoing shoulder arthroplasty.

The incidence of surgical-site infections did not significantly differ between the vancomycin and the placebo group (4.5 percent vs 3.5 percent; relative risk, 1.28, 95 percent confidence interval [CI], 0.94–1.73; p=0.11).

When looking at the type of surgery, the proportion of patients who had surgical-site infections in the vancomycin and placebo groups were 5.7 percent vs 3.7 percent (relative risk, 1.52, 95 percent CI, 1.04–2.23) for knee arthroplasty and 3.0 percent vs 3.1 percent (relative risk, 0.98, 95 percent CI, 0.59–1.63) for hip arthroplasty, respectively.

Adverse events were recorded in 1.7 percent of patients in the vancomycin group and in 1.7 percent of patients in the placebo group. Specifically, hypersensitivity reactions occurred in 1.2 percent vs 0.5 percent of patients (relative risk, 2.20, 95 percent CI, 1.08–4.49) and acute kidney injury in 2.1 percent vs 3.6 percent of patients (relative risk, 0.57, 95 percent CI, 0.39–0.83), respectively.