Preoperative antibiotic allergy testing may improve safe cefazolin usage, which may lead to lower periprosthetic joint infection rates, according to results presented at The Hip Society Specialty Day in Las Vegas.
“We now recommend that all patients with a question of allergy preoperatively be tested and that cefazolin be used preferentially when deemed safe by the surgical team,” Cody C. Wyles, MD, said in his presentation of the study, which received The John Charnley Award.
Use of cefazolin
Wyles and colleagues evaluated nearly 30,000 primary hip and knee arthroplasties in patients included in the Mayo Clinic Total Joint Registry and Mayo Clinic Allergy Testing Registry, 12% of whom underwent preoperative allergy testing. He said 97% of patients with a report history of allergy to penicillin or cephalosporins who subsequently who underwent allergy testing were cleared for safe cephalosporin use. Overall, 95% of patients received cefazolin and 5% received non-cefazolin antibiotics.
There were no differences between patients in the cefazolin and non-cefazolin groups in terms of antibiotic cement used in their surgery. However, a significantly higher percentage of patients in the non-cefazolin group were positive for MRSA and had an American Society of Anesthesiologists (ASA) classification of 3 or greater vs. the cefazolin group, according to Wyles.
“There was a significantly improved survivorship free of infection in patients treated with cefazolin,” Wyles said, and noted the most rapid period of divergence occurred during the early weeks after surgery when antibiotics would be expected to exert their greatest effect.
Researchers extrapolated the survivorship data in a number need to treat analysis and determined164 patients would need to receive cefazolin to prevent one periprosthetic joint infection (PJI) at 1 year and 84 patients would be needed to prevent one PJI at 10 years postoperatively.
“Taking that a step further to a theoretical cohort of 1 million primary total hip and knee arthroplasties, we can potentially prevent over 6,000 periprosthetic joint infections at 1 year and over 11,000 in 10 years,” Wyles said.
When evaluating the type of infecting organism in the two groups, Wyles noted that no cases of MRSA were identified in the non-cefazolin group.
“Now that might seem intuitive given that vancomycin and clindamycin have excellent coverage against that organism, but it highlights the fact that they have poor coverage against alternative organisms,” he said. “I think what these data show is the potential role for dual therapy in the setting of patients who are positively colonized with MRSA to use both cefazolin and vancomycin.”
Although cefazolin use was the only factor found to decrease the risk of PJI in the univariate analysis, the risk of PJI was independently increased with elevated BMI, total knee arthroplasty vs. total hip arthroplasty and ASA classification of 3 or greater. After researchers adjusted for important patient-specific factors, multivariable analysis showed a decrease in the risk of PJI by 32% with the use of cefazolin, Wyles said.
“In light of the data I presented this morning, I submit to you that antibiotic choice is a readily modifiable factor in the vast majority of patients, whereas we know that BMI is only partially modifiable, and arthroplasty type and ASA classification are non-modifiable risk factors,” Wyles said. – by Casey Tingle
Wyles CC, et al. Increased PJI following primary TKA and THA with alternatives to cefazolin: The value of allergy testing for antibiotic prophylaxis. Presented at: The Hip Society Specialty Day; March 16, 2019; Las Vegas.
Cody C. Wyles, MD, can be reached at Mayo Clinic, 200 First St. SW, Rochester, MN 55905; email: email@example.com.
Disclosure: Wyles reports no relevant financial disclosures.