In a prospective observational study, influenza vaccination prevented hospitalization among older home care patients

Abstract 

Objective

The aim of the study is (1) to describe the prevalence of vaccination against influenza in older home care patients and (2) to investigate the protective effect of influenza vaccination for hospitalization events.

Study Design and Setting

This is an observational study conducted in four large cohorts of elderly patients in home care during the 1998–1999, 1999–2000, 2000–2001, and 2001–2002 influenza seasons. We analyzed data from the Italian Silver Network Home Care project. A total of 2,201 patients were enrolled in the present study. The main outcome measures were prevalence of vaccination against influenza and the rate of hospitalization according to vaccination status and influenza season.

Results

The rate of influenza vaccination was around 48% of the studied sample. During the follow-up including the peak of influenza and the total influenza season, 412 subjects (40%) were hospitalized among vaccinated compared to 610 subjects (59%) among not vaccinated (P<0.001). After adjusting for age, gender, location of home care program, and all the variables significantly different between vaccinated and not-vaccinated subjects, vaccinated subjects were less likely to be hospitalized compared to not-vaccinated subjects (OR, 0.73; 95% CI 0.60–0.90).

Conclusions

Vaccination against influenza has an important prognostic implication for frail geriatric patients living in the community.

Keywords: Influenza vaccination, Hospitalization, Geriatric assessment, MDS, Home care, Frail elderly