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E-1 APPENDIX E USER HEALTH BENEFITS The benefits of physical activity in enhancing overall health are These reports from various state agencies are complemented well established. Physical activity reduces the risk of chronic diseases with more academically oriented research. For example, Colditz including coronary heart disease (170, 205209), hypertension (210), (101) reviewed past literature on the economic costs of inactivity Type II (non-insulin dependent) diabetes mellitus (211, 212), osteo- and concluded that the direct costs for those individuals reporting porosis (213, 214), cancer (215217) and mental illness (95, 218220). lack of physical activity was estimated to average approximately Inversely, reduced levels of physical activity are also associated with $128 per person. A separate analysis by Pratt et al. (102) analyzed mortality rates in general (221223). a stratified sample of 35,000 Americans from the 1987 national The task of attaching monetary amounts to levels of physical Medical Expenditures Survey. Examining the direct medical costs activity is a more challenging endeavor. One attempt to this gen- of men and women who reported physical activity versus those who eral inquiry has been completed by Wang et al. (93) who derived did not reveals that the mean net annual benefit of physical activ- cost-effectiveness measures of bicycle/pedestrian trails by divid- ity was $330 per person in 1987 dollars. An alternative method ing the costs of trail development and maintenance by selected used a cost-of-illness approach to attribute a proportion of medical physical activity-related outcomes of the trails (e.g., number of and pharmacy costs for specific diseases to physical inactivity in trail users). The average annual cost for persons becoming more 2001 (97). The authors first identified medical conditions associ- physically active was found to be $98; the cost was $142 for per- ated with physical inactivity and then collected claims data related sons who are active for general health, and $884 for persons who to those conditions from approximately 1.6 million patients 16 and are active for weight loss. older from a large, Midwest health plan. While the resulting con- Estimating the effect of physical activity on direct medical ditions from lack of physical inactivity include depression, colon costs is a strategy more often employed, though considerably less cancer, heart disease, osteoporosis, and stroke, the results from this straightforward. Part of the reason for ambiguity in this line of study conclude that claims costs at the health plan attributable to research is that an unsettled question looms as to how much phys- physical inactivity translates to $57 per member. One challenge of ical activity is required to realize certain health benefits (i.e., what these analyses is the decision regarding whether or not to include is the elasticity?) (88, 94, 95). In the field of public health, this diseases causally related to obesity or not. The Garrett paper did matter is often approached from the perspective of dose-response not, which may account for the lower estimates of cost of inactiv- relationships. The aim is to learn what change in amount, inten- ity per person. sity, or duration of exposure (in this case, cycling) is associated A different approach than the dichotomized strategy estimates with a change in risk of a specified outcome (in this case, cost of the impact of different modifiable health risk behaviors and mea- health care). sures their impact on health care expenditures. After gathering Existing literature examining relationships between levels of information from more than 61,500 employees of six employers physical activity and health costs varies considerably in methodol- gathered over a five-year study period, Goetzel et al. (87) focused ogy and scope. The majority of existing studies pursue a dichot- on a cohort of just over 46,000 employees, one-third of whom omized approach, separating respondents into two classes: those that satisfy the accepted "dose" of 30 minutes per day for five days were considered to be sedentary (or inactive). The analysis found and those who do not. In this first group of studies, there are at least that a "risk-free" individual incurred approximately $1,166 in five statewide reports whose methodology and assumptions are rel- average annual medical expenditures while those with poor health atively general in nature. In most cases, estimates are derived from habits had average annual medical expenditures of more than an aggregation of medical expenditures that can in some form be $3,800. Thus, they estimated the per-capita annual impact of poor traced back to physical inactivity. For example, a study commis- exercise habits to be approximately $172. Pronk et al. (89) also sioned by the Michigan Fitness Foundation (96) concentrated on identify the relationship between modifiable health risks and short- the economic costs to the residents of Michigan. The authors used term health care charges. This research surveyed a random sample estimates (acknowledged to be conservative) to derive direct costs of 5,689 adults aged 40 years or older enrolled in a Minnesota (e.g., medical care, workers' compensation, lost productivity) and health plan. Multivariate analysis on the modifiable health risks indirect costs (e.g., inefficiencies associated with replacement (diabetes, heart disease, body mass index, physical activity and workers). The final amount totaled $8.9 billion in 2003 ($1,175 per smoking status) concluded that an additional day of physical activ- resident). A 2002 report from the Minnesota Department of Health ity (above zero) would yield a 4.7 percent reduction in charges (or (97) estimates that in 2000, $495 million was spent treating dis- a $27.99 reduction). The overarching result of the study is that eases and conditions that would be avoided if all Minnesotans were obesity costs approximately $135 per member per year, and those physically active. This amount converts to over $100 per resident. with low fitness (inactivity) cost approximately $176 per member Additional reports claim that too little physical activity was per year. responsible for an estimated $84.5 million ($19 per capita) in hospi- From this discussion, a couple of matters stand out with respect to tal charges in Washington State (98), $104 million ($78 per capita) in understanding such relationships and ultimately informing applica- South Carolina (99), and $477 million in hospital charges in Georgia ble methods. First, annual per capita cost savings vary between $19 ($79 per capita) (100). and $1,175 with a median value of $128 (see Table 25). Second,

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E-2 TABLE 25 Estimated annual per capita cost savings some studies are disaggregate in nature and estimate costs by in- (direct and/or indirect) of physical activity (103) patient, outpatient, and pharmacy claims; others compare average Study/Agency Per Capita Cost Savings ($) healthcare expenditures of physically active versus inactive indi- Washington State Department of Health 19 viduals. Third, some use a dichotomized approach to operational- Garrett et al. 57 ize physically active individuals while others employ a modifiable South Carolina Department of Health 78 Georgia Department of Human health risks approach and do so in a relatively continuous scale. The 79 Resources studies are difficult to compare because some include different Colditz (1999) 92 conditions, outpatient and pharmacy costs, and actual paid amounts Minnesota Department of Health >100 Goetz et al. 172 rather than charges. Nonetheless, existing literature provides ade- Pronk et al. 176 quate, though developing, methodologies for estimating the public Pratt 330 health impact of bicycle facilities in terms of economic impacts. Michigan Fitness Foundation 1,175