Influenza infection has higher risk of postoperative complications than COVID-19 in shoulder arthroplasty patients

Introduction The COVID-19 pandemic has captured the attention of healthcare systems worldwide, and testing remains a mainstay of preoperative testing before all surgical procedures, including shoulder arthroplasty. Other viral illnesses, specifically influenza, while still having severe complications, are either overshadowed by testing for COVID-19 or not tested at all. Methods A multi-institutional cohort study using the TriNetX network examined patients undergoing total or hemi shoulder arthroplasty from January 2020 to March 2024. Matched cohorts were created: one with influenza and one with COVID-19 infection, 14 days before surgery. Results A total of 3233 and 18,209 patients were included in the influenza and COVID-19 cohorts, respectively. The matched cohorts both consisted of 3232 patients. Patients in the influenza cohort had a significantly higher risk of sepsis (95% CI [1.264, 2.528], p = 0.001), stroke (95% CI [1.160, 5.052], p = 0.015), readmission (95% CI [1.271, 1.860], p < 0.001), anemia (95% CI [1.263, 2.088], p < 0.001), transfusion (95% CI [1.022, 2.330], p = 0.037), ED visits (95% CI [1.104, 1.314], p < 0.001) and inpatient hospitalization (95% CI [1.173, 1.295], p < 0.001) during the perioperative period. The COVID-19 cohort had a significantly higher risk of opioid analgesics usage (95% CI [0.909, 0.973], p < 0.001) in the perioperative period. Discussion Patients with recent influenza infections prior to shoulder arthroplasty have a greater risk of medical complications, with no difference in implant-related complications compared to COVID-19, emphasizing the need for perioperative patient counseling and surgical planning.