New research indicates that patients with rheumatic diseases are more likely to be culture negative for prosthetic joint infections (PJI) than patients with osteoarthritis (OA).
Researchers from Hospital for Special Surgery and Weill Cornell Medicine in New York City recently published an abstract of their work, “Clinical Features of Prosthetic Joint Infections in Patients with Rheumatic Diseases vs Osteoarthritis,” in volume 71, issue S10 of Arthritis and Rheumatology.
Susan Goodman, M.D., a rheumatologist at Hospital for Special Surgery (HSS) and Weill Cornell Medicine explained the unique difficulties inherent in diagnosing joint infections in rheumatoid arthritis (RA) patients to OTW, “It is important to understand the challenge of diagnosing prosthetic joint infection in patients with underlying RA. Many of the cardinal signs of infection such as elevations of ESR [erythrocyte sedimentation rate] or CRP [C-reactive protein], or elevated white blood cells in synovial fluid, are similar in both infection, and active joint flares.”
“Moreover, patients with infections may simply have a joint that is achier than the other joints, so missing the diagnosis can occur. However, there is no direct evidence that compares the levels of the diagnostic tests for prosthetic joint infection with the levels in RA patients without infection.”
Using a retrospective cohort of total hip arthroplasty (THA)/ total knee arthroplasty (TKA) prosthetic joint infections from 2009 to 2016, Dr. Goodman and her colleagues sought to identify the clinical and microbiological features of THA and TKA prosthetic joint infection in rheumatic disease and osteoarthritis patients.
The HSS/Weill Cornell team identified a total of 807 prosthetic joint infection cases, including 36 with rheumatic disease and 771 with OA. The team found that a higher proportion of patients with rheumatic disease prosthetic joint infection were culture negative versus those with OA and prosthetic joint infection.
Fewer patients with culture negative rheumatic disease met the prosthetic joint infection histopathology criteria compared to those with culture negative OA. On average, culture negative rheumatic disease patients were younger than culture negative OA patients, but this was no different than those with rheumatic disease who were culture positive.
The researchers found no difference in age, smoking, diabetes, or Charlson comorbidities between those with culture negative rheumatic disease and culture positive rheumatic disease, however a trend towards higher prevalence of prior prosthetic joint infection in the culture negative rheumatic disease group was found. Dr. Goodman and her colleague found no differences in surgical treatment or use of biologics and disease-modifying antirheumatic drugs between culture negative and culture positive rheumatic disease patients. Among culture positive patients, the team found no difference in diabetes, comorbidities, smoking, or history of prosthetic joint infection, but more patients with rheumatic disease were female and used glucocorticoids.
The authors acknowledge that this was a small sample size and that this has limited their analysis. “It is important to study this further and directly compare the tests in patients with prosthetic joint infection and patients with active RA, so cut-points can be validated. Other diagnostic modalities also need to be pursued in this challenging patient population, and metagenomics sequencing is a promising method that should be accurate in patients with RA.
