Summary

PJI patients spend 135.8 more days and $2138.9 more dollars on antibiotic use when compared to non-PJI patients.

Abstract

Introduction

Prosthetic joint infection (PJI) is the most common indication for TKA revision and is associated with higher morbidity and mortality. In addition, it poses a substantial economic burden on patients and the healthcare system as it increases and lengthens hospital stays, requires long-term antibiotic therapy, and almost always needs at least one surgical intervention. Our study aims to estimate the total days and cost of therapeutic antibiotic use among patients with prosthetic joint infection (PJI) after total knee arthroplasty (TKA).

Methods

We conducted an observational cohort study with a 2-year follow-up using the IBM Watson MarketScan Commercial Claims and Encounters Database. Patients with osteoarthritis who underwent primary TKA between January 1 and September 30, 2017, were included. Primary exposure was the diagnosis of PJI within 90 days post-TKA. The primary outcome was the days of antibiotics use, and the secondary outcome was the costs associated with antibiotics, both over the 2-year period post-TKA. Propensity score matching analysis was performed matching with patient and provider characteristics.

Results

A total of 13,201 patients (female 59.0%, age 59.4±8.4, PJI 1.0%) were included in the study. After propensity score matching, patients with PJI had 135.8 more days of antibiotic use than patients without PJI (165.1 days vs 29.3 days, P<0.001). PJI patients also spent $2138.9 more on antibiotics than those without PJI ($2242.0 vs $103.1, P<0.001). The attributable cost of antibiotics use for PJI patients is estimated to be over $12 million in two years in the United States and reflects 814,000 antibiotic-days of therapy.

Conclusion

By extrapolating the result of this study, the cost of antibiotic use attributable for PJI is estimated to be over $12 million over the first 2 years post-TKA in the United States, and accounts for over 814,000 antibiotic days. By reducing knee prosthesis infections, we could expect to see significant secondary antibiotic stewardship gains in this common surgical population.