Moderating effects of immunosuppressive medications and risk factors for post-operative joint infection following total joint arthroplasty in patients with rheumatoid arthritis or osteoarthritis

Abstract

Objective: Inconclusive findings about infection risks, importantly the use of immunosuppressive medications in patients who have undergone large-joint total joint arthroplasty, challenge efforts to provide evidence-based perioperative total joint arthroplasty recommendations to improve surgical outcomes. Thus, the aim of this study was to describe risk factors for developing a post-operative infection in patients undergoing TJA of a large joint (total hip arthroplasty, total knee arthroplasty, or total shoulder arthroplasty) by identifying clinical and demographic factors, including the use of high-risk medications (i.e., prednisone and immunosuppressive medications) and diagnoses [i.e., rheumatoid arthritis (RA), osteoarthritis (OA), gout, obesity, and diabetes mellitus] that are linked to infection status, controlling for length of follow-up.

Methods: A retrospective, case-control study (N = 2212) using de-identified patient health claims information from a commercially insured, U.S. dataset representing 15 million patients annually (from January 1, 2007 to December 31, 2009) was conducted. Descriptive statistics, t-test, chi-square test, Fisher's exact test, and multivariate logistic regression were used.

Results: Male gender (OR = 1.42, p < 0.001), diagnosis of RA (OR = 1.47, p = 0.031), diabetes mellitus (OR = 1.38, p = 0.001), obesity (OR = 1.66, p < 0.001) or gout (OR = 1.95, p = 0.001), and a prescription for prednisone (OR = 1.59, p < 0.001) predicted a post-operative infection following total joint arthroplasty. Persons with post-operative joint infections were significantly more likely to be prescribed allopurinol (p = 0.002) and colchicine (p = 0.006); no significant difference was found for the use of specific disease-modifying anti-rheumatic drugs and TNF-α inhibitors.

Conclusion: High-risk, post-operative joint infection groups were identified allowing for precautionary clinical measures to be taken.

Keywords: Case–control study; Immunosuppressive medications; Infections; Perioperative management; Risk factors; Total joint arthroplasty.

Figure 1

Derivation of Sample.

Figure 2

Comparisons of medication usage rates between cases and controls. Note: Above each bar is listed the percent of patients taking that drug who have RA, whether in the case or control group; this should be contrasted to 8%, the percent of patients with RA in the full sample of cases and controls. For example, all patients taking Adalimumab who did not get infections had RA, and 80% of those in the case group who were taking this drug had RA.

Figure 3

Comparison of use of TNFα inhibitors and traditional DMARDs between cases and controls. *TNFα inhibitors including Adalimumab, Certolizumab, Etanercept, Infliximab, and Golimumab ±Traditional DMARDS including Azathioprine, Hydroxychloroquine, Leflunomide, and Methotrexate Note: Above each bar is listed the percent of patients taking that class of drug who have RA, whether in the case or control group; this should be contrasted to 8%, the percent of patients with RA in the full sample of cases and controls. For example, 93% of patients taking a TNFα inhibitor who did not get infections had RA, and 69% of those in the case group who were taking this class of drug had RA.