A STUDY OF THE IMPACT OF INFLUENZA ON THE FUNCTIONAL STATUS OF FRAIL OLDER-PEOPLE

Background: Excess hospitalization and death are well-known impacts of influenza on older people; however, little is known regarding the imp act of influenza on functional status. We hypothesized that frail olde r people are at risk of functional decline as an outcome of influenza. Objective: To measure the effect of acute influenza on the physical a nd mental status of older patients residing in nursing homes. Methods: Our study was conducted in 6 nursing homes that participated in the M edicare Influenza Vaccine Demonstration and experienced laboratory-con firmed outbreaks of influenza in 1991 and 1992. A case-comparison desi gn was used. One hundred sixteen of 131 residents who developed influe nza-like illness and survived at least dr months served as the case su bjects; 127 of 132 residents without influenza-like illness who surviv ed served as the comparison subjects. Measures of functional status 1 to 2 months before outbreak and 1 to 2 months and 3 to 4 months after outbreak were collected from medical records. Matched pairs analyses w ere conducted to ascertain changes in selected measures of functional status within each of the study groups. Wilcoxon signed rank tests for statistical significance were used. Results: Among surviving case sub jects and comparison subjects, 25% and 15.7%, respectively, experience d decline in at least 1 major function (P=.04). Case subjects experien ced significant decline in independence in bathing, dressing, and mobi lity while comparison subjects experienced decline in mental status. C onclusions: Within the limitations of this study, influenza is observe d to cause decline in major physical functions in more than 9% of surv ivors. Such disabling outcomes constitute an important new measure of impact of influenza on the frail elderly.