(Research Hub Theater) Risk of Septic Arthritis After Corticosteroid Joint Injections: A Retrospective Propensity Score-matched Cohort Analysis

Background and/or Objectives: Septic arthritis (SA) is a rare but serious complication of corticosteroid joint injections (CSI) which can lead to joint damage and possible mortality. There is limited research defining the true risk of SA following large joint CSI. Literature review of SA after CSI suggests rates anywhere from 0.08% to 0.002%. This analysis seeks to determine the absolute and relative risks of SA after large joint CSI across 48 health care organizations.

Design: A retrospective cohort study.

Setting: TriNetX a multicenter and nationwide de-identified, longitudinal database in the United States.

Participants: Electronic health records identified patients who had an ambulatory visit with a diagnosis of arthritis followed by a second ambulatory visit within three months. Patients with gonococcal infection, recent orthopedic surgery or procedures, or prior diagnosis of SA were excluded. Patients were categorized based on presence or absence of large joint corticosteroid injection (CSI) during the second ambulatory visit. Patients were propensity-score matched (1:1) based on risk factors such as demographics, comorbidities, or non-health related risk factors. The risk of SA was compared between matched cohorts with 95% confidence intervals.

Interventions: Not applicable

Main Outcome Measures: The primary outcome was SA diagnosis between 1 and 21 days after the second visit.

Results: The search identified 231,561 patients in the injection group. Propensity score matching was then performed with a pool of 1,907,703 potential control patients for a final matched sample of 231,544 in each group. The risk of SA without major joint CSI is 0.168% whereas the risk after major joint CSI is 0.098%. The absolute risk difference for CSI compared to no CSI was -0.07% (95% CI -0.049% - -0.091%; p < 0.0001).

Conclusions: This study suggests that current standard practices related to major joint CSI do not increase the risk of SA.