Research article
Economic Analysis of Physical Activity Interventions

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Background

Numerous interventions have been shown to increase physical activity but have not been ranked by effectiveness or cost.

Purpose

This study provides a systematic review of physical activity interventions and calculates their cost-effectiveness ratios.

Methods

A systematic literature review was conducted (5579 articles) and 91 effective interventions promoting physical activity were identified, with enough information to translate effects into MET-hours gained. Cost-effectiveness ratios were then calculated as cost per MET-hour gained per day per individual reached. Physical activity benefits were compared to U.S. guideline–recommended levels (1.5 MET-hours per day for adults and 3.0 MET-hours per day for children, equivalent to walking 30 and 60 minutes, respectively).

Results

The most cost-effective strategies were for point-of-decision prompts (e.g., signs to prompt stair use), with a median cost of $0.07/MET-hour/day/person; these strategies had tiny effects, adding only 0.2% of minimum recommended physical activity levels. School-based physical activity interventions targeting children and adolescents ranked well with a median of $0.42/MET-hour/day/person, generating an average of 16% of recommended physical activity. Although there were few interventions in the categories of “creation or enhanced access to places for physical activity” and “community campaigns,” several were cost effective. The least cost-effective categories were the high-intensity “individually adapted behavior change” and “social support” programs, with median cost-effectiveness ratios of $0.84 and $1.16 per MET-hour/day/person. However, they also had the largest effect sizes, adding 35%–43% of recommended physical activity, respectively. Study quality was variable, with many relying on self-reported outcomes.

Conclusions

The cost effectiveness, effect size, and study quality should all be considered when choosing physical activity interventions.

Introduction

Regular physical activity has positive effects on both physical and mental health,1, 2 and numerous interventions have successfully increased physical activity. Yet differences in both the types of interventions and how they are measured make comparisons difficult. Cost-effectiveness analysis (CEA) could aid decision makers in allocating resources efficiently3 through synthesizing information about the effectiveness, costs, and benefits of interventions. Of course, decision makers have to take other criteria into account, such as the distribution of benefits and costs, perceptions of fairness, and political support,4 but choosing the most cost-effective interventions maximizes the total benefits of limited resources.

A small number of physical activity interventions have been evaluated from a cost-effectiveness perspective, but in isolation and generally not in a way that allows comparisons across studies. One reason is that the relationship between physical activity interventions and long-run outcomes remains fairly speculative, and seemingly minor changes in assumptions (such as how physical activity effects are sustained over time) have a larger impact on cost-effectiveness estimates than the intervention itself. No study so far has compared the cost effectiveness of dozens of effective physical activity interventions now published and recommended for general use.5

Ideally, CEA follows the reference case of the U.S. Panel on Cost-Effectiveness in Health and Medicine,6 which uses a nonspecific health outcome (quality-adjusted life-years, or QALYs), takes a social perspective on costs to include all costs (including the opportunity costs of participants), and discounts long-run costs and outcomes. At this point, this may be too demanding for physical activity interventions, partly because relating changes in physical activity resulting from an intervention to QALYs involves assumptions about health benefits and partly because important short-term benefits (such as mood improvement or decrease in musculoskeletal complaints7, 8) are often not adequately captured in standard QALY methodology.

In this paper, therefore, a less ambitious approach is taken by using an outcome that is specific to physical activity, namely the quantity of physical activity produced among the population reached, measured in MET-hours. Similarly, costs are limited to actual intervention costs, which leaves out the more speculative (although not necessarily unimportant) effects of the intervention on healthcare costs, productivity, or participants' opportunity costs. This approach allows us to compare a larger set of physical activity interventions, even though it does not allow comparisons to other types of interventions like smoking cessation. To provide a benchmark, a crude calculation was used based on the estimated medical costs of inactivity.9, 10 In that case, any intervention with a cost-effectiveness ratio below this benchmark may actually be cost-saving.

Section snippets

Methods

Both existing systematic reviews were used and a public database search was conducted to retrieve candidate studies for inclusion. All interventions listed in two systematic reviews were selected: Kahn et al.5 and van Sluijs et al.11 A systematic literature search was then carried out using seven databases (MEDLINE, Sportdiscus, PsycINFO, Transportation Research Information Services, Enviroline, Sociological Abstracts, and Socio Sci Search) and included interventions published between 2000 and

Results

Figure 1 provides a flow chart of the systematic literature review. A total of 91 studies with 141 intervention arms were identified meeting the current inclusion criteria (1.6% of articles screened). Many studies that were excluded did not specify either the intensity or duration of the activity gained, but offered outcomes like an increased frequency of activity only. Of the included studies, 48 used RCT or controlled trial study design. Although the primary goal of 81 interventions was to

Discussion

The most cost-effective interventions provide the highest benefit for each dollar invested, which in some cases might lead to overall savings from a societal perspective. In the present study, the most cost-effective interventions reached a large number of people with low-intensity (and low-cost) efforts. Interventions like stair-climbing prompts may be extremely cost effective, but because they increase physical activity by only a minuscule amount, they alone could not greatly increase the

Recommendations for Evaluating Future Physical Activity Interventions

Future interventions to promote physical activity should take care to report resources utilized and costs. They should also measure the frequency, intensity, and duration of physical activity gained, so that their costs and effectiveness can be ranked against other interventions to help better inform public health policies. Many studies in the current review had relatively small samples. Future studies should have sufficient sample sizes (statistical power) to reliably detect more realistic

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      Likewise, some international systematic reviews of economic evaluations of public health interventions for increasing physical activity and healthy diet found the majority of interventions to be cost-effective (Flego et al., 2014a; White et al., 2018; Wu et al., 2011a; Garrett et al., 2011). However, these studies reported variations in qualities of the available economic evaluations and limitations in transferring findings across contexts (Flego et al., 2014a; White et al., 2018; Wu et al., 2011a; Garrett et al., 2011). Moreover, economic evaluations are context sensitive and transferability of results is affected by factors including methodological (perspective, costing approach etc.), health systems (variation in price, practice, accessibility, technology) and population (disease incidence/prevalence, case mix, life expectancy, and health status preferences) (Welte et al., 2004).

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