Safety of Influenza Vaccination During Orthopaedic Surgery Hospitalizations.

Background: Despite national recommendations, influenza vaccination rates during hospitalizations remain low. Inpatient hospitalization for orthopaedic surgery remains a largely missed opportunity for vaccination. To address potential concerns regarding safety, we evaluated whether influenza vaccination during hospitalization for orthopaedic surgery increases evaluations for infection postdischarge because patients and clinicians often cite fear of this potential outcome.

Methods: This was a retrospective cohort study that was conducted among patients of a large integrated healthcare organization aged ≥6 months who were hospitalized for an orthopaedic surgery (defined by International Classification of Diseases, Ninth Revision procedure codes) between September 1 and March 31 from 2011 to 2014. Using propensity score matching (1:1) to adjust for confounding, we assessed the association between influenza vaccination during an inpatient stay for orthopaedic surgery and rates of readmission, emergency department visits, outpatient visits, fever (temperature ≥38.0°C), and evaluations for infections less than 7 days postdischarge.

Results: Overall, 2,395 hospitalizations with inpatient vaccination and 21,708 hospitalizations without inpatient vaccination were identified. Following successful balance of covariates (standardized difference <0.1 for all covariates) through 1:1 propensity score matching, we included 2,376 exposed patients and 2,376 unexposed patients in the matched analysis. In adjusted analyses, compared with those who were not vaccinated during hospitalization, those vaccinated during an inpatient stay for orthopaedic surgery had no statistically significant increase in readmission (relative risk [RR] = 1.00, 95% confidence interval [CI]: 0.75 to 1.34), emergency department visits (RR = 1.14, 95% CI: 0.93 to 1.41), fever (RR = 1.31, 95% CI: 0.81 to 2.12), or clinical workups for infection (RR = 1.08, 95% CI: 0.98 to 1.18). A marginally increased risk of outpatient visits in the 7 days postdischarge was detected (RR = 1.13, 95% CI: 1.02 to 1.26).

Discussion: There was no evidence of a substantial increased risk of infection-related outcomes associated with influenza vaccination during hospitalization for orthopaedic surgery. Our data support the recommendation of vaccinating orthopaedic surgery patients against influenza perioperatively.