Intra‐articular and soft‐tissue corticosteroid injections and risk of infections: Population‐based self‐controlled‐risk‐interval design

PURPOSE: Chronic and short-term treatment with oral corticosteroids is associated with an increased risk of infection. However, the potential risk of infection that may be associated with intra-articular and soft-tissue injections of corticosteroids has not been reported. The aim of this study was to assess the risk for infection following intra-articular or soft-tissue corticosteroid injections. METHODS: Self-controlled-risk-interval study with 15 732 adults who were treated with intra-articular or soft-tissue corticosteroid injections during 2015-2018. The study was conducted in a large Israeli Health Maintenance Organization. We self-matched the participants and analyzed the incidence of infection over three periods: an exposure-period of 90 days following the injection, and two 90-day control periods. We identified the occurrence of several common infections in the patient's electronic medical record and analyzed the incidence rates of all infections (composite end-point) as well as each infection separately. RESULTS: The incidence of any infection was higher during postexposure period compared with the control periods (46.5 vs. 42.1 events per 1000 persons), number needed to harm was 227 persons. Self-matching analysis showed increased incidence-rate-ratio (IRR) for the combined incidence of infections in the post-exposure period compared with the control periods (IRR = 1.10, 95% confidence interval [CI] 1.01-1.21). A sensitivity analysis showed that the highest IRR was during the first 30 days (IRR = 1.19, 95% CI 1.03-1.38), with higher IRR for patients aged 65 years and older (IRR = 1.37, 95% CI 1.08-1.73). CONCLUSIONS: Intra-articular and soft-tissue corticosteroids injections may be associated with an increased risk of infections; however, the absolute risk increase is low.