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Title: Designing Clinical Trials of Intervention for Mobility Disability: Results from the Lifestyle Interventions and Independence for Elders (LIFE) Pilot Trial

Author
item ESPELAND, MARK - WAKE FOREST UNIV
item GILL, THOMAS - YALE UNIV
item GURALNIK, JACK - NIA
item MILLER, MIKE - WAKE FOREST UNIV
item Fielding, Roger
item NEWMAN, ANNE - UNIV PITTSBURGH
item PAHOR, MARCO - UNIV FLORIDA

Submitted to: Journal of Gerontology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/9/2007
Publication Date: 11/1/2007
Citation: Espeland, M.A., Gill, T.M., Guralnik, J., Miller, M.E., Fielding, R., Newman, A., Pahor, M. 2007. Designing Clinical Trials of Intervention for Mobility Disability: Results from the Lifestyle Interventions and Independence for Elders (LIFE) Pilot Trial. Journal of Gerontology. 62(11):1237-1243.

Interpretive Summary: As the life expectancy in the United States has continued to rise, the maintenance of physical and cognitive independence of older Americans has emerged as a major clinical and public health priority. A critical factor in an older person’s ability to function independently is mobility, or the ability to move without assistance. Older people who lose mobility are less likely to remain in the community, have higher rates of morbidity, mortality, and hospitalizations and experience a poorer quality of life. Several studies suggest that regular physical activity may improve physical performance, but definitive evidence showing that mobility disability can be prevented is lacking. We conducted “Lifestyle Interventions and Independence For Elders-LIFE” pilot study. Clinical trials to assess interventions for mobility disability are critically needed, however data for efficiently designing such trials are lacking. Results are described from the LIFE pilot clinical trial, in which 424 volunteers aged 70-89 years were randomly assigned to one of two interventions -- physical activity or a healthy aging education program -- and followed for a planned minimum of 12 months. We evaluated the longitudinal distributions of four standardized outcomes to contrast how they may serve as primary outcomes of future clinical trials: ability to walk 400 meters, ability to walk 4 meters in <10 seconds, a physical performance battery, and a questionnaire focused on physical function. Changes in all four outcomes were related to each other statistically throughout the study. We found that one test, the ability to walk 400 meters, provided the smallest sample size projections (i.e. appeared to be the most efficient outcome). A four-year trial based on a primary outcome of 400 meter walk would require a sample size of 855 to 2,222 to detect an intervention effect. Future clinical trials of interventions designed to influence mobility disability may be most efficient if they adopt the ability to complete a 400 meter walk as their primary outcome.

Technical Abstract: Clinical trials to assess interventions for mobility disability are critically needed, however data for efficiently designing such trials are lacking. Our results are described from the LIFE pilot clinical trial, in which 424 volunteers aged 70-89 years were randomly assigned to one of two interventions -- physical activity or a healthy aging education program -- and followed for a planned minimum of 12 months. We evaluated the longitudinal distributions of four standardized outcomes to contrast how they may serve as primary outcomes of future clinical trials: ability to walk 400 meters, ability to walk 4 meters in