DISCUSSION
Among patients with orthopedic implant infections treated with intent to cure using a rifampin-containing antibiotic regimen at the MVAHCS, 82% had clinical success. Although this is lower than the success rates reported in clinical trials, this is not entirely unexpected.5,7 In most clinical trials studying DAIR and rifampin for PJI, patients are excluded if they do not have an acute staphylococcal infection in the setting of a well-fixed prosthesis without evidence of a sinus tract. Such exclusion criteria were not present in our retrospective study, which was designed to evaluate the real-world practice patterns at this facility. The population at the US Department of Veterans Affairs (VA) is older, more frail, and with more comorbid conditions than populations in prior studies. It is possible that patients with characteristics that would have caused them to be excluded from a clinical trial would be less likely to receive rifampin therapy with the intent to cure. This is suggested by the significantly higher prevalence of chronic infections (68%) in the without-intent-to-cure group compared with 22% in the intent-to-cure group. However, there were reasonably high proportions of participants included in the intent-to-cure group who did have conditions that would have led to their exclusion from prior trials, such as chronic infection (22%) and implant age ≥ 2 months (40%).
When evaluating participants by the age of their implant, treatment success rose to 93% for patients with implants < 2 months old compared with 65% for patients with older implants. This suggests that participants with a newer implant or more recent infection have a greater likelihood of successful treatment, which is consistent with the results of previous clinical trials.5,10 Considering how difficult multiple surgeries can be for older adult patients with comorbidities, we suggest that DAIR with a rifampin-containing regimen be considered as the primary treatment option for early PJIs at the MVAHCS. We also note inconsistent adherence to IDSA treatment guidelines on rifampin therapy, in that patients without intent to cure were prescribed a regimen including rifampin. This may reflect appropriate variability in the care of individual patients but may also offer an opportunity to change processes to improve care.
Limitations
Our analysis has limitations. As with any retrospective study evaluating the efficacy of a specific antibiotic, we were not able to attribute specific outcomes to the antibiotic of interest. Since the choice of antibiotics was left to the treating health care practitioner, therapy was not standardized, and because this was a retrospective study, causal relationships could not be inferred. Our analysis was also limited by the lack of intent to cure in 28 participants (36%), which could be an indication of practitioner bias in therapy selection or characteristic differences between the 2 groups. We looked for signs of infection failure 1 year after the completion of antimicrobial therapy, but longer follow-up could have led to higher rates of failure. Also, while participants’ infections were considered cured if they never sought further medical care for the infection at the MVAHCS, it is possible that patients could have sought care at another facility. We note that 9 patients were excluded because they were unable to complete a treatment course due to rifampin AEs, meaning that the success rates reported here reflect the success that may be expected if a patient can tolerate and complete a rifampin-based regimen. This study was conducted in a single VA hospital and may not be generalizable to nonveterans or veterans seeking care at other facilities.
Conclusions
DAIR followed by a short course of IV antibiotics and an oral regimen including rifampin and another antimicrobial is a reasonable option for veterans with acute staphylococcal orthopedic device infections at the MVAHCS. Patients with a well-placed prosthesis and an acute infection seem especially well suited for this treatment, and treatment with intent to cure should be pursued in patients who meet the criteria for rifampin therapy.
Acknowledgments
We thank Erik Stensgard, PharmD, for assistance in compiling the list of patients receiving rifampin and another antimicrobial.