摘要：Objectives. Although risk factors for indoor falls among older individuals have been well studied, little is known about the etiology of outdoor falls. We examined risk factors for outdoor falls among middle-aged and older adults. Methods. We analyzed data on the most recent fall during the past year among participants aged 45 years and older in the control group (N=2193) of a case–control study of fractures. The study was conducted at 5 Northern California Kaiser Permanente Medical Centers between 1996 and 2001. Results. Falls occurred outdoors more often than indoors among most age groups. Study participants who reported more leisure-time physical activity had a higher risk for outdoor falls, and participants who were in poorer health had a greater risk for indoor falls. Most outdoor falls (73%) were precipitated by environmental factors, such as uneven surfaces and tripping or slipping on objects, and usually occurred on sidewalks, curbs, and streets. Walking (47.3%) was the most common fall-related activity. Conclusions. Outdoor falls among adults aged 45 years and older were frequently attributable to modifiable environmental factors. With the widespread promotion of active lifestyles among older people, improvements in their outdoor environment are urgently needed. Falls are the leading cause of injury-related deaths and hospital admissions among older adults. Each year, more than one third of the elderly persons in the United States fall, 1 – 3 and 10% of these falls result in injuries that require medical attention. 3 – 6 Fall-related injuries in the United States cost more than $20 billion each year, and by 2020, the total annual cost of these injuries is expected to reach $32.4 billion. 7 Many studies have identified home hazards and personal risk factors for falls. 8 – 13 North-ridge et al. 8 showed the importance of home hazards in falls among active versus inactive elderly persons, and they noted that measures are needed to prevent falls among the active elderly. To date, little research or public attention has been focused on outdoor falls; however, outdoor falls occur at least as often as indoor falls among older adults. 14 – 17 Indoor falls tend to occur among frail individuals, 15 – 17 but outdoor falls tend to occur among more active people and are heavily influenced by characteristics of the outdoor environment. 15 – 17 In an era when active living is promoted by numerous international and national health agencies, 18 – 20 a better understanding of how the outdoor environment influences the risk for falls is important. Although increased physical activity is associated with decreased risk for chronic conditions such as obesity and cardiovascular disease, and although some national reports and guidelines suggest that physical activity may reduce an older person’s risk for falling, 21 , 22 little empirical evidence exists about the association between physical activity, particularly outdoor activity, and the occurrence of falls. Detailed data on falls and the people who experience them from the control group of a case–control study of fractures in Northern California provided an opportunity for examining this issue. We investigated the circumstances of outdoor falls, identified environmental and personal risk factors for outdoor falls, compared the frequency of self-reported outdoor and indoor falls among older adults, and examined differences in the characteristics of outdoor and indoor falls and the people who experienced them.
