Background/Purpose: Infections after orthopaedic surgeries are feared complications, leading to costly treatments and successive interventions. A higher postoperative infection risk is discussed in patients with inflammatory rheumatic diseases (IRDs). This is especially relevant since patients with aggressive diseases frequently need orthopaedic surgery. In a retrospective study of a large cohort of orthopaedic surgeries the risk of postoperative infections was examined in relation to diagnosis, type of surgery and preoperative management of conventional disease modifying medication (cDMARDs) and tumor necrosis factor alpha (TNF-α)-inhibitors.

Methods: 37’137 patients (50’359 surgeries) were followed in the hospital’s surgery registry over 8 years. Diagnoses were categorized as inflammatory or degenerative/posttraumatic and operation-related infections were registered. In a subgroup with known medication prior to surgery the preoperative management and influence on the infection rate was analyzed. Chi-squared test was used to assess associations between two discrete variables. Univariate and multiple logistic regression analyses were used to identify risk factors for infection. Odds ratios (OR) together with the corresponding 95% confidence intervals (95%CI) were provided.

Results: Among the 50’359 surgeries 422 (0.8%) surgery-related infections were identified, 373/47’887 (0.8%) cases in the degenerative group and 49/2’472 (2.0%) in the IRD group, indicating a significantly higher infection rate in the IRD group (OR=2.576, 95%CI 1.907, 3.479; p<0.001). Complete information on medication use and its discontinuation or otherwise prior to surgery was available for 1’329/2472 (54%) cases in the IRD group. The use of TNF-α-inhibitors was documented in 171/1’329 (13%) cases. In 49/171 (29%) cases, TNF-α-inhibitors were discontinued more than three administration intervals before surgery. These were considered “ex-users”. This occurred more often with drugs having a short administration interval. In the remaining 122/171 (71%) cases, the time lag was 3 administration intervals or less, and these were considered “at risk”. The use of more than one cDMARD (OR=2.425, 95%CI 1.034, 5.688; p=0.042) and TNF-α-antagonists before surgery (OR=2.627, 95%CI 1.119, 6.168; p=0.027) were each associated with an increased infection rate. The risk of infection was almost 10-fold when surgery was performed within one administration interval (OR=10.047, 95%CI 1.170, 86.286; p=0.035). Approximately 81% of the patients treated with infliximab were in this group (≤1 administration interval), whereas only 33% of the users of adalimumab and 24% of the etanercept users had their last intake of the drug one administration interval or less before surgery.

 Conclusion: The risk of postoperative infection is elevated in patients with IRDs compared to degenerative/posttraumatic cases. Special attention should be paid when more than one cDMARD or TNF-α-inhibitors with long administration intervals are used. The last intake of TNF-α-inhibitors should be at least more than one administration interval before surgery, as the risk of postoperative infection is significantly increased if surgery occurs within this period.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/infection-risk-after-orthopaedic-surgery-in-patients-with-inflammatory-rheumatic-diseases-with-focus-on-discontinuation-of-tnf-alpha-inhibitors/