Relation between influenza vaccination and outpatient visits, hospitalization, and mortality in elderly persons with chronic lung disease.

Background: Influenza vaccine is underused in groups targeted for vaccination.

Objective: To define the effects of influenza and the benefits of influenza vaccination in elderly persons with chronic lung disease.

Design: Retrospective, multiseason cohort study.

Setting: Large managed care organization.

Patients: All elderly members of a managed care organization who had a previous diagnosis of chronic lung disease.

Measurements: Outcomes in vaccinated and unvaccinated persons for the 1993-1994, 1994-1995, and 1995-1996 influenza seasons were compared after adjustment for baseline demographic and health characteristics. All data were obtained from administrative databases.

Results: Vaccination rates were greater than 70% for each season. Among unvaccinated persons, hospitalization rates for pneumonia and influenza were twice as high in the influenza seasons as they were in the interim (noninfluenza) periods. Influenza vaccination was associated with fewer hospitalizations for pneumonia and influenza (adjusted risk ratio, 0.48 [95% CI, 0.28 to 0.82]) and with lower risk for death (adjusted odds ratio, 0.30 [CI, 0.21 to 0.43]) during the influenza seasons. It was also associated with fewer outpatient visits for pneumonia and influenza and for all respiratory conditions.

Conclusions: For elderly persons with chronic lung disease, influenza is associated with significant adverse health effects and influenza vaccination is associated with substantial health benefits, including fewer outpatient visits, fewer hospitalizations, and fewer deaths. Health care providers should take advantage of all opportunities to immunize these high-risk patients.