Researchers from Loyola University in Chicago have delved into the issue of how often does chronic antibiotic suppression prevent reoperation due to a prosthetic joint infection (PJI). Their study, “Predictors of Success With Chronic Antibiotic Suppression for Prosthetic Joint Infections,” appears in the February 7, 2022, edition of The Journal of Arthroplasty.
“Recurrent infection in total joint arthroplasty after attempted surgical management remains a problem,” explained co-author Rebecca Burr, M.D. of the Department of Orthopaedic Surgery and Rehabilitation at the Loyola University Medical Center. “Chronic antibiotic suppression is an alternative option for a small subset of these patients, however there is limited existing literature on outcomes and predictors of success when chronic suppression is used.”
To begin their analysis the Loyola research team needed to establish a uniform start date for the chronic antibiotic suppression therapies under review. They decided to fix the start date by way of a thorough review of the physician’s infectious disease and orthopedic notes.
The team then documented the chronic antibiotic suppressive regimen, dosing, and patient monitoring by the infectious disease team. “Success” was defined as zero reoperation after starting chronic antibiotic suppression therapy. “Failure” was defined by the team as reoperation after starting chronic antibiotic suppression therapy or if the patient died of causes directly related to their prosthetic joint infection.
Finally, the team measured their time-to-event models using elapsed time in months from the index infection date to date of reoperation, and patients not experiencing reoperation were documented from their last known follow-up date.
The team collected data from 45 prosthetic joint infections (31 knees, 14 hips) which had been treated with chronic antibiotic suppression (median follow-up of 50 months). The team was able to document a prosthetic joint infection success for 67% of the cases using chronic antibiotic suppression.
When the researchers controlled for body mass index and Gram status of the organism, they found that total hip arthroplasty patients were less likely than total knee arthroplasty patients to require reoperation. They also determined that individuals with Gram-positive infections were less likely than those with Gram-negative infections to require reoperation.
Dr. Burr told OTW, “Our time-to-event analysis for various patient and infection scenarios enables surgeons to provide improved guidance and expectations to patients with this problem. Our goal wasn’t to advocate for a specific treatment, but rather to report the results of our cohort of patients where suppression was given and leave the conclusion to the readers.”
