title: Daily walking and life expectancy of elderly people in the iowa 65+ rural health study.
abstract: The purpose of this paper is to investigate the hypothesis that outdoor daily walking, as an exercise, has an effect on the rate of mortality among those elderly people in the Iowa 65+ Rural Health Study (RHS). RHS is a prospective longitudinal cohort study of 8 years follow-up from 1981 to 1989. It consists of a random sample of 3,673 individuals (1,420 men and 2,253 women) aged 65 or older living in Washington and Iowa counties of the State of Iowa. Our analysis was conducted only on those non-institutional individuals who could without any help walk across a small room; this reduced the total number of individuals in the study to 2,717. Moreover, a total of 923 individuals died during the period of the study. The life histories of those individuals were obtained and divided into two cohorts; one containing 1,134 who exercise daily by walking and the other containing 1,583 who do not exercise daily by walking. The interviewers asked participants about 17 medical conditions, from which 13 are included in our study. We found that daily walking exercise is related inversely to total mortality before and after adjusting for the other factors in particular for age group and health conditions. We observed that hazard ratio (HR) of death was the highest among those individuals having a history of cancer (HR = 2.971) and history of stroke (HR = 2.127). However, individuals with a history of stroke in the "daily walking group" have HR = 0.856 and their risk of death were reduced by 81% compared to those in no "daily walking group."
authors.affiliation: Jiann-Ping Hsu College of Public Health, Georgia Southern University Statesboro, GA, USA.
authors.forename: Hani M
authors.initials: HM
authors.lastname: Samawi
keywords: Cox regression; Kaplan Meier estimate; daily walk; hazard ratio; health conditions; life expectancy; proportional hazards model; survival function