Preoperative Allergy Testing for Patients Reporting Penicillin and Cephalosporin Allergies is Economically Justified in Preventing Infection after Total Shoulder Arthroplasty.

Abstract

The use of alternative antibiotics to cefazolin has been associated with increased risk of infection after shoulder arthroplasty. Routine preoperative allergy testing in patients reporting penicillin and cephalosporin allergies increases the number able to receive cefazolin and may reduce the occurrence of infection after shoulder arthroplasty, but the financial viability of this practice is unclear. We used break-even modeling to determine the economic viability of routine preoperative allergy testing for infection prevention in total shoulder arthroplasty patients reporting penicillin and cephalosporin allergies. Allergy testing cost ($248.24), infection rates after shoulder arthroplasty following use of non-cefazolin antibiotics (3.09%), and infection-related care costs ($55,243) were derived from the literature. A break-even equation using these variables was developed to determine the absolute risk reduction (ARR) in the infection rate that would economically justify the routine implementation of preoperative allergy testing. The number needed to treat (NNT) was calculated from the ARR. Preoperative allergy testing is considered economically justified if it prevents at least 1 infection out of 223 shoulder arthroplasties (ARR = 0.45%). These protocols remained economically viable at varying allergy testing costs, initial infection rates, and infection-related care costs. Routine preoperative penicillin allergy testing is an economically justified infection prevention strategy among patients reporting penicillin and cephalosporin allergies in the setting of elective shoulder arthroplasty. Widespread implementation of this practice may considerably reduce the economic and societal burden associated with prosthetic infections.