Butler AM, Layton JB, Dharnidharka VR, Sahrmann J, Weber DJ, McGrath L. Comparative effectiveness of high-dose versus standard-dose influenza vaccine among patients on chronic hemodialysis. Presented at the 35th ICPE International Conference on Pharmacoepidemiology & Therapeutic Risk Management; August 27, 2019. Philadelphia, PA. [abstract] Pharmacoepidemiol Drug Saf. 2018 Aug 20; 28(S2):485. doi: 10.1002/pds.4864.

BACKGROUND: The standard‐dose influenza vaccine (SDV) may not prevent influenza‐related outcomes in patients on chronic dialysis. Little is known about the comparative effectiveness of high‐dose influenza vaccine (HDV) versus SDV in this population.

OBJECTIVES: To compare the risk of all‐cause mortality, hospitalization due to influenza or pneumonia, and influenza‐like illness during the influenza season among adult recipients of HDV versus SDV.

METHODS: We performed a cohort study using Medicare data from the United States Renal Data System (USRDS) for patients with end‐stage renal disease (ESRD). We constructed yearly cohorts of adults with ESRD undergoing in‐center hemodialysis during five individual influenza seasons (2010/11 to 2014/15). We required vaccination to occur prior to the start of each influenza season. Baseline covariates were ascertained during the 6‐month period prior to vaccination. Follow‐up began at the start of influenza season. Patients were eligible for inclusion in multiple yearly cohorts, thus our unit of analysis was the influenza‐season. To examine the relationship between vaccine dose and effectiveness outcomes, we estimated risk differences (RD) using propensity score weighting of Kaplan–Meier functions, accounting for a wide range of patient‐ and facility‐level characteristics. For non‐mortality outcomes, we used competing risk methodology to account for high mortality in the dialysis population. Patients were censored at the earliest of a competing risk event (death for non‐mortality outcomes), loss of Medicare Parts A or B, kidney transplant, peritoneal dialysis, subsequent influenza vaccine, or end of influenza season. The primary analysis was conducted in adults aged ≥65 years, and a secondary analysis was conducted in adults aged <65 years.

We identified 255,281 eligible adult patients who contributed 507,552 unique patient‐seasons. Within 225,215 patient‐seasons among adults aged ≥65 years, 97.4% received SDV and 2.6% received HDV. We observed similar risk estimates for HDV and SDV recipients for mortality (RD, −0.1%; 95% CI, −0.9% to 0.8%), hospitalization due to influenza or pneumonia (RD, 0.2%; 95% CI, −0.7% to 0.9%), and influenza‐like illness (RD, 0.0%; 95% CI, −1.5% to 1.1%). Our findings were similar among adults aged <65, as well as within subgroups defined by influenza season, age group, years on dialysis, month of vaccination, and vaccine valence.

CONCLUSIONS: HDV does not appear to provide additional protection beyond the SDV against all‐cause mortality or influenza‐related outcomes in the adult dialysis population.

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