1953. Comparative Effectiveness of High- vs. Standard-Dose Influenza Vaccine on Hospitalization for Acute Myocardial Infarction in Nursing-Home Residents: A Post-hoc Analysis From a Large Cluster-Randomized Trial

BACKGROUND: There is growing evidence supporting the role of influenza vaccine in decreasing the risk of cardiovascular (CV) events, including acute myocardial infarction. The development of vaccines targeting older adults, such as high-dose (HD) and adjuvanted formulations, offers the promise of enhanced CV protection in this high-risk group. We evaluated whether a HD trivalent vaccine was associated with a reduced incidence of acute CV events (ACE) among nursing home (NH) residents, compared with a standard-dose trivalent vaccine (SD). METHODS: This is a secondary analysis of data from a single-blind, pragmatic, cluster-randomized comparative effectiveness trial. We recruited and randomized Medicare-certified NHs located within 50 miles of a CDC influenza reporting city to facility-wide standard of care for the residents to either HD or SD as the vaccine offered for the 2013–2014 influenza season. Long-stay residents 65 and older in a fee-for-service Medicare plan were eligible for the study. Study staff were masked to NH allocations and raw data access to minimize bias. Outcome data of interest were obtained from the Centers for Medicare and Medicaid Services (CMS). The primary outcome was hospitalization for an acute cardiovascular event (ACE), defined as acute myocardial infarction, atrial fibrillation or heart failure between November 2013 and May 2014. Hazard ratios were estimated from cox-proportional hazard models with facility random effects to account for clustering. We conducted stratified analyses by gender and baseline cardiovascular disease. All models were adjusted for individual and facility level baseline characteristics. RESULTS: A total of 823 facilities with 38,672 eligible residents were randomized into balanced groups. Facility and resident characteristics were comparable. The incidence of hospitalization for ACE was significantly lower in HD than SD facilities (10.1% vs. 11.0%; adjusted HR 0.92; 95% CI 0.85–0.95; P-value 0.015). Figure 1 shows adjusted HR for each outcome; selected subgroups are presented in Figure 2. [Image: see text] [Image: see text] CONCLUSION: High-dose flu vaccine reduces the risk of hospitalization for ACE in long-term care residents by 8% relative to standard-dose vaccine. Registration NCT01815268. Funding sanofi pasteur. DISCLOSURES: E. Saade, sanofi pasteur: Collaborator, Research support. Seqirus: Collaborator, Research support. N. Joyce, sanofi pasteur: Collaborator, Research support. Seqirus: Collaborator, Research support. J. Ogarek, sanofi pasteur: Collaborator, Research support. Seqirus: Collaborator, Research support. H. E. Davidson, sanofi pasteur: Collaborator, Research support. Seqirus: Collaborator, Research support. D. Canaday, sanofi pasteur: Collaborator, Research support. Seqirus: Collaborator, Research support. A. Yasin, sanofi pasteur: Collaborator, Research support. Seqirus: Collaborator, Research support. T. Shireman, Sanofi-Pasteur: Grant Investigator, Grant recipient. V. Mor, sanofi pasteur: Collaborator, Research support. Seqirus: Collaborator, Research support. S. Gravenstein, sanofi pasteur: Collaborator, Research support. Seqirus: Collaborator, Research support.