Odds of Influenza in Patients Receiving Intra-Articular Corticosteroid Injections: A Cohort Study.

OBJECTIVE: Although intra-articular corticosteroid (IACS) is injected locally, some systemic absorption occurs, potentially causing immunosuppression in recipients. This study examined odds of influenza in patients who received IACS compared to matched controls.

DESIGN: Adults in our health system who received IACS from May 2012 through April 2018 were 1:1 matched to adults without IACS. The primary outcome was overall odds of influenza. Secondary analyses examined influenza odds by timing of IACS, joint size, and vaccination status.

RESULTS: 23,368 adults (mean age 63.5 years, 62.5% female) received IACS and were matched to a control. While there was no difference in influenza odds by IACS status overall (OR 1.13,[95%CI,0.97-1.32]), patients receiving IACS during influenza season had higher odds of influenza than matched controls (OR 1.34,[95%CI,1.03-1.74]). Furthermore, unvaccinated patients who received IACS during influenza season had higher influenza odds compared to matched controls (OR 1.41,[95%CI,1.04-1.91]), while there was no difference among vaccinated patients.

CONCLUSION: Patients receiving IACS injections during influenza season had higher odds of influenza. However, vaccination appeared to mitigate this risk. Patients receiving IACS injections should be counseled on infection risk and importance of vaccinations. Further research is needed to examine IACS effects on other viral illnesses.