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. 2013 Dec;51(12):1106-13.
doi: 10.1097/MLR.0b013e3182a50297.

Hospitalization and skilled nursing care are predictors of influenza vaccination among patients on hemodialysis: evidence of confounding by frailty

Leah J McGrath  1 , Stephen R Cole, Abhijit V Kshirsagar, David J Weber, Til Stürmer, M Alan Brookhart
Affiliations

Hospitalization and skilled nursing care are predictors of influenza vaccination among patients on hemodialysis: evidence of confounding by frailty

Leah J McGrath et al. Med Care. 2013 Dec.

Abstract

Background: Observational studies of preventive medications, such as vaccinations, can suffer from the healthy-user bias because vaccinated patients may be healthier than unvaccinated patients. Indicators of health status and frailty suitable for attenuating this bias could be identified in administrative data.

Objective: To examine the association of baseline variables and time-dependent hospitalization and skilled nursing care with the receipt of influenza vaccination in patients with end-stage renal disease.

Research design: Observational cohort study using United States Renal Data System files each year from 1999 to 2005.

Subjects: Population-based cohorts that included >115,000 adult, hemodialysis patients each year.

Measures: We estimated hazard ratios for the association of baseline variables and time-dependent hospitalization days and skilled nursing days with influenza vaccination, controlling for demographic and baseline health status variables.

Results: Vaccination coverage increased from 47% in 1999 to 60% in 2005. Patients with any length of hospitalization were less likely to be vaccinated, however, the association was stronger in patients with longer stays [15-25 d: hazard ratio=0.64 (95% confidence interval, 0.62-0.65); 26-30 d: 0.40 (0.38-0.42)]. Patients with any length of skilled nursing care of >1 day had similar estimates; these patients were also less likely to be vaccinated [26-30 d: 0.66 (0.64-0.69)].

Conclusions: Patients with long hospitalizations or skilled nursing stays were less likely to be vaccinated suggesting evidence of the healthy-user effect. These variables could be used to account for bias in studies of preventive services in patients on dialysis.

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Figures

FIGURE 1
FIGURE 1
Cumulative, administered influenza vaccine doses by month and year. *Normal year is defined as the average of 1999, 2002, 2003, and 2005.
See this image and copyright information in PMC

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