Risk factors for infection following total joint arthroplasty in rheumatoid arthritis.

OBJECTIVES

Determine risk factors for infection following hip or knee total joint arthroplasty in patients with rheumatoid arthritis.

METHODS

All rheumatoid arthritis patients with a hip or knee arthroplasty between years 2000 and 2010 were identified from population-based administrative data from the Calgary Zone of Alberta Health Services. Clinical data from patient charts during the hospital admission and during a one year follow-up period were extracted to identify incident infections.

RESULTS

We identified 381 eligible procedures performed in 259 patients (72.2% female, mean age 63.3 years, mean body mass index 27.6 kg/m2). Patient comorbidities were hypertension (43.2%), diabetes (10.4%), coronary artery disease (13.9%), smoking (10.8%) and obesity (32%). Few infectious complications occurred: surgical site infections occurred within the first year after 5 procedures (2 joint space infections, 3 deep incisional infections). Infections of non-surgical sites (urinary tract, skin or respiratory, n=4) complicated the hospital admission. The odds ratio for any post-arthroplasty infection was increased in patients using prednisone doses exceeding 15 mg/day (OR 21.0, 95%CI 3.5-127.2, p=<0.001), underweight patients (OR 6.0, 95%CI 1.2-30.9, p=0.033) and those with known coronary artery disease (OR 5.1, 95%CI 1.3-19.8, p=0.017). Types of disease-modifying therapy, age, sex, and other comorbidities were not associated with an increased risk for infection.

CONCLUSION

Steroid doses over 15 mg/day, being underweight and having coronary artery disease were associated with significant increases in the risk of post-arthroplasty infection in rheumatoid arthritis. Maximal tapering of prednisone and comorbidity risk reduction must be addressed in the peri-operative management strategy.