Geographic Variation in Influenza Vaccination among US Nursing Home Residents: A National Study

Objectives: Estimates of influenza vaccine use are not available at the county level for U.S. nursing home (NH) residents but are critically necessary to guide implementation of quality improvement programs aimed at increasing vaccination rates. Furthermore, estimates that account for differences in resident characteristics between counties are unavailable. We estimated risk-standardized vaccination rates among short- and long-stay NH residents by U.S. county and identified drivers of geographic variation. Methods: We conducted a retrospective cohort study utilizing 100% of 2013-2015 fee-for-service Medicare claims, Minimum Data Set assessments, Certification and Survey Provider Enhanced Reports, and LTCFocUS. We separately evaluated short-stay (<100 days) and long-stay (≥100 days) residents aged ≥65 years old across the 2013-2014 and 2014-2015 influenza seasons. We estimated county-level risk-standardized vaccination rates (RSVRs) via hierarchical logistic regression adjusting for 32 resident-level covariates. We then used multivariable linear regression models to assess associations between county-level NHs predictors and RSVRs. Results: The overall study cohort consisted of 2,817,217 residents in 14,658 NHs across 2,798 counties. Short-stay residents had lower RSVRs than long-stay residents (2013-2014: median [IQR], 69.6% [62.8-74.5] vs 84.0% [80.8-86.4]). Counties with the highest vaccination rates were concentrated in the Midwestern, Southern, and Northeast US. Several modifiable facility-level characteristics were associated with increased RSVRs, including higher registered nurse to total nurse ratio and higher total staffing for licensed practical nurses, speech language pathologists, and social workers. Characteristics associated with lower RSVRs included higher percentage of residents restrained, with a pressure ulcer, and NH-level hospitalizations per resident-year. Conclusions: Substantial county-level variation in influenza vaccine use exists among short- and long-stay NH residents. Quality improvement interventions to improve vaccination rates can leverage these results to target NHs located in counties with lower risk-standardized vaccine use.