Obesity and falls in older people: Mediating effects of disease, sedentary behavior, mood, pain and medication use
Introduction
Internationally, the older adult population (aged 65 years and older) is increasing (United Nations, 2013). It is estimated that 27.3% of the population in the United Kingdom (UK), 22.4% of the population in Australia, and 21.1% of the population in the United States (US) will be aged 65 years and older by 2050 (United Nations, 2013). Around one-third of people aged 65 years and older living in the community will fall each year and many older people fall more than once (Campbell et al., 1989, Tinetti et al., 1988). Following a fall, some older people can develop a fear of falling, which often then decreases their level of physical activity as they attempt to prevent further falls (King & Tinetti, 1995).
For older individuals, fall-related injuries are the most common cause of injury-related mortality and injury-related hospitalization (Bradley, 2013, Stevens et al., 2006). Fall-related injuries in older individuals represent a substantial cost to health systems (Schuffham et al., 2003, Stevens et al., 2006). Within NSW, Australia's most populous state with approximately 460,000 people aged 65 years and older (Australian Bureau of Statistics, 2012), the annual direct cost of health care following a fall is estimated at $558.5 million (Watson, Clapperton, & Mitchell, 2011).
In many high income countries, the prevalence of obesity in older individuals is increasing (OECD, 2012). In the US, it is estimated that 31% of individuals aged 60 years and older are obese (Body Mass Index: BMI ≥ 30) (Houston, Nicklas, & Zizza, 2009). In Australia, 71% of individuals aged 65–74 years, 60% of those aged 75–84 years and 42% of those aged 85+ years are overweight or obese (BMI ≥ 25) (Australian Institute of Health and Welfare, 2010). With population aging, the number of obese older individuals is expected to continue to increase (Australian Institute of Health and Welfare, 2002, Elia, 2001, Houston et al., 2009).
For older people, obesity can introduce or exacerbate existing health conditions (such as diabetes, arthritis or cardiovascular disease (Elia, 2001, Houston et al., 2009)), and can adversely affect an individual's ability to perform day-to-day activities (Elia, 2001). In turn, poor health can result in physical inactivity that can influence an individual's weight. Obesity has been associated with an increased risk of falls among older people (Fjeldstad et al., 2008, Kelsey et al., 2010, Mitchell et al., 2014). However, it is not certain whether factors commonly associated with falls and/or obesity mediate this risk. A mediator (or intervening variable) is considered to be a factor that plays a part in contributing to the relationship between an independent variable and an outcome (Baron & Kenny, 1986). An assessment of the capacity of a factor to act as a mediator between obesity and falls and the effects that mediation can have on the association between obesity and falls have not been extensively explored. The aim of this research is to examine the extent to which the association between obesity and falls is mediated by related factors including chronic disease, sedentary behavior, mood, pain, and medication use using information obtained from a population-based survey.
Section snippets
Sampling design
The NSW Falls Prevention Baseline Survey was undertaken in 2009 by the NSW Ministry of Health (Centre for Health Advancement and Centre for Epidemiology and Research, 2010). A representative sample of 5681 older people (aged 65+ years) living in the community, with a private telephone, were surveyed across NSW regarding their falls experience, knowledge and perception of falls, participation and awareness of physical activity and health status. The full details concerning the development of the
Characteristics of obese and non-obese individuals
Overall, 19.7% (95%CI 18.5–21.0) of individuals were categorized as obese. Obese individuals had a significantly higher proportion of falls, diabetes, arthritis, heart disease/angina, high blood pressure, moderate/extreme pain or discomfort, moderate/extreme anxiety or depression, used 4 or more medications, and used tranquilizers, anti-depressants or blood thinners compared to non-obese individuals. A significantly lower proportion of obese individuals undertook strengthening activities on 2
Discussion
This study aimed to identify mediators for the relationship between obesity and falls in older people. It found that obese individuals have a 25% higher risk of falling compared to older individuals in all other weight groups. Previous research has shown inconsistent findings for the association between obesity and falls, with one study finding no evidence of an association (Rosenblatt & Grabiner, 2012), and other studies finding a higher risk of falls for obese older individuals (Fjeldstad et
Conclusions
This research highlights the complex multifactorial nature of fall risk which includes body habitus. Among older people, obesity has been associated with an increased risk of falling and this study has identified a number of mediating factors for the association between obesity and falls, including sedentary behavior, chronic health conditions, such as anxiety/depression and diabetes, and medication use, particularly use of sleeping tablets. This study has also quantified the impact on the
Conflict of interest
Nil.
Acknowledgements
R Mitchell and L Harvey were supported by the NSW Ministry of Health. The authors would like to thank the Center for Population Health and the Center for Epidemiology and Evidence at the NSW Ministry of Health for providing access to the NSW Falls Prevention Baseline Survey data analysed in this study.
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