Key Takeaways
- Overall, our view is that advocacy for a long-term public education campaign to address low physical activity might be an extremely cost-effective cause area.
- However, with respect to the scientific evidence, while the link between physical inactivity and disease is indisputable, there is considerable uncertainty as to effectiveness of specific interventions like mass media and community-based interventions in actually increasing physical activity levels.
- Additionally, while the experts we consulted unanimously agreed that the global burden of physical inactivity will continue to grow, there was more disagreement over the best way to counter this. Overall, they leaned in favour of taking a population-level approach, but experts also flagged out that this is hard to do or sustain. This is especially so from a historical perspective, given that leisure-time physical activity has not been how humans have actually gotten sufficient physical activity (vs being active due to work and chores).
- At the same time, the downsides to addressing physical inactivity as a cause area are minimal, even less so than other areas like nutrition policy, where questions of infringing upon people's freedom of choice or having perverse policy consequences do not even arise.
Executive Summary
Taking into account (a) the expected benefits of addressing low physical activity, in terms of improved health and increased income, while also factoring in (b) the expected costs on the economic front and (c) the tractability of advocacy for a long-term public education campaign to increase physical activity, CEARCH finds the marginal expected value of advocacy for such a long-term public education campaign to address low physical activity to be 12,065 DALYs per USD 100,000, which is around 10x as cost-effective as giving to a GiveWell top charity – which are themselves some of the very best in the world. (CEA).
See short report here.
- Introduction: This report on low physical activity is the culmination of two iterative rounds of research: (i) an initial shallow research round involving 1 week of desktop research; and (ii) a subsequent intermediate research round involving 2 weeks of desktop research and expert interviews;
- Importance: Physical inactivity is a risk factor for multiple diseases, including heart disease, diabetes, stroke, and cancer. Globally, low physical activity is certainly a problem, and will have a direct health burden of 19 million disability-adjusted life years (DALYs) in 2025, as well as an indirect health burden of 60,000 DALYs via an increased risk of depression. There is also an accompanying net economic burden equivalent to foregoing the doubling of income for 14 million people; note that people typically value such income doublings at around 1/5th of a year of healthy life. And this problem of physical inactivity is only expected to grow between 2025 and 2100, as a result of factors like urbanization, ageing, and population growth.
- Neglectedness: Government policy is far from adequate, with only 10% of countries implementing the top WHO-recommended policy of a long-term public education campaign to promote physical activity; this is not expected to change much going forward – based on the historical track record, any individual country has only a 0.1% chance per annum of introducing this recommended policy. There is, of course, significant heterogeneity – some countries like Singapore have a good strategy in place, but other countries (e.g. Australia, US, Germany) are nowhere near this, and compared to such high-income countries, developing countries fare even worse.
- Tractability: There are many potential solutions to the problem of low physical activity (e.g. a public education campaign; built environment interventions to make cities more walkable; digital interventions like apps and wearables; and point-of-decision prompts like posters by staircases); however, we find that the most cost-effective solution is likely to be advocacy for a public education campaign to promote physical activity; this campaign is inclusive of both a mass media campaign and accompanying community-based interventions such as a pedometer-based National Steps Challenge. The theory of change behind this intervention is as such:
- Step 1: Lobby a government to implement a long-term public education campaign to increase physical activity.
- Step 2(a): The mass media campaign component of the long-term public education campaign in a single country reduces physical inactivity and its related global disease burden.
- Step 2(b)(i): The community component of the long-term public education campaign in a single country increases physical activity in a single country.
- Step 2(b)(ii): Increased physical activity from the community component reduces the global disease burden of low physical activity.
- Using the track record of past walkability policy and nutrition policy advocacy efforts and of general lobbying attempts (i.e. an "outside view"), and combining this with reasoning through the particulars of the case (i.e. an "inside view"), even while adjusting for counterfactuals, our best guess is that funding advocacy campaigns will have an 11% chance of successfully enacting a long-term public education campaign to increase physical activity. Meanwhile, based on various meta-analyses, and after robust discounts and checks (e.g. for a conservative theoretical prior of a null hypothesis; for endogeneity; for study populations being unrepresentative; or for publication bias), we expect that a mass media campaign in a single country will reduce the global disease burden of low physical activity by 0.07%; that a community-based intervention (particularly a pedometer-based national challenge) can increase participants' average number of daily steps by 1000, which will in turn reduce the global disease burden of low physical activity by 0.0005%. Note that while the WHO recommends a holistic approach, we expect the mass media campaign to have the bulk of the impact.
- There are additional complications to the intervention. In particular, we expect on average a 7 year gap between when an advocacy intervention begins and when the health impact actually kicks in (-12% impact).
- Outstanding Uncertainties: There are a number of outstanding uncertainties, of which the four most important involve: (a) our use of point estimations (n.b. relying on them is reasonable given that we are ultimately interested in mean estimates, but caution is also warranted, as significant variance is possible); (b) the very simplified methodology we use to project the future disease burden of low physical activity; and (c) the massively complicated extrapolations we had to make in calculating the effect sizes of a mass media and pedometer campaigns; and (d) the highly uncertain estimates of the probability of advocacy success.
- Conclusion: Overall, our view is that advocacy for a long-term public education campaign to address low physical activity might be an extremely cost-effective cause area, but more research is needed.
I'm curious why mass media campaigns would be the recommended action given that meta-analysis of mass media campaigns don't seem indicate a reduction in sedentary behavior nor achievement of recommended physical activity levels, (though they do promote some increase in walking.) Lobbying to invest in the built environment seems cheaper and also more effective in the long run. Organizations like Strong Towns, Bloomberg City Labs, various walking and biking safety groups advocate/lobby for walkable neighborhood changes that are very affordable, if not free, like loosening zoning to allow for mixed-use buildings, multiple homes/businesses in one lot, reduced parking minimums. Many of the changes only require legislative change, since businesses or developers take on cost of new construction. Urban3 consultancy group has considerable research into the significantly higher tax revenues cities get from new residential and commercial developments, replacing underutilized spaces like parking lots. I would guess that influencing national health organizations (like national cancer or diabetes associations) to see walkable neighborhoods as possible could increase the pace of change. Other ways to get other groups to join the lobbying effort might be to clarify via mass media campaigns the link between car-centric infrastructure to the high rates of road fatalities (the main way to make roads safer is to build pedestrian/biking infrastructure (build buffers to remove "stroads", bike lanes = narrow roads, sidewalk bump-outs = increase visibility, both of these decrease speeding). Or clarify the health impacts of children (developmental delays and asthma) for those who live on car-centric streets. I would guess these mass media campaigns would have a counterfactual difference (though indirectly to your goal) since road fatalitiy preventability and children health outcomes from even just proximity to cars are things people are not aware of, whereas almost everyone is aware that physical activity is good.
Thanks for the thoughtful comment!
(1) On the evidence base for mass media interventions: Our choice to prioritize mass media (and so attempt more detailed modelling) was based on it (a) looking good in cost-effectiveness at a a shallower research stage with a less; (b) being recommended by the WHO as the most cost-effective intervention for promoting physical activity; and (c) generally, mass media interventions being 2nd only to policy in cheap scalability.
We relied on the study you cited (Abioye, Hajifathalian & Danaei), and took into consideration all three meta-analyses (impact on sedentary behaviour, sufficient walking, and sufficient physical activity), while discounting based on the degree to which measured outcome is dissimilar to GBD/WHO definitions of sufficient physical activity (>= 600 METs minutes per week). We did not exclude the sedentary meta-analysis results based on the fact that its reliant on a low quality outlier, but did perform our own analysis, to discount it (and the other meta-analyses) on the basis of underlying study quality (especially with respect to endogeneity) and publication bias.
We also considered whether the studies being from high-income countries biases the result (n.b. on the one hand, ageing high income countries are older and more sedentary, which implies a larger group of potential beneficiaries and greater population-level effect size; on the other hand, as Rosie Bettle of FP notes in her report on mass media interventions, its potentially the case that basic healthcare knowledge is more lacking in poorer countries, so you can - as with vaccine uptake - increase uptake there in a way).
Overall, we do think there's is an effect, but it's highly uncertain, and there's a real chance it's zero. For more details, see the ultra-long (and fairly tedious) discussion in this cell (Tractability:B12) of the CEA.
(2) Built environment changes: We did take a look at this option (see Annex A in our CEA for a qualitative discussion of the available intervention options, and the relevant evidence base/expert feedback). We ultimately prioritized mass media (for reasons discussed above), but I do think such environment changes will be substantially more impactful but also much, much harder.
For one, if we're talking about not just high-income countries but LMICs, the situation is very different. Zoning is just much less a factor than in the rich world (they may not have much on the books, and what's on the books may not be enforced), so the problem they face isn't the one that the US/UK etc face and which YIMBYs are trying to solve. Their major cities are also extremely dense, and people have low vehicle ownership rates (but worse congestion and air pollution). Making these cities more walkable isn't just a matter of allowing dense housing, but spending a lot of money to improve public transport, solving air pollution etc, and that's a fundamentally much harder ask for poor countries.
Nice one as usual Joel!
The 7 year wait for results is a really tough one. Governments don't love investing in interventions where the benefits will only be reaped by the opposition who wins the next election, and funders don't like waiting that long. Also a 7 year delay to results makes research tricky as well.
Not a reason not to act, but certainly a complicating factor.
Hi Nick!
Yep, that's definitely a concern for governments (same with other policy interventions for nutrition). For funders - to be fair, that's not much different from direct delivery (e.g. for vaccinations or contraception, we can't really know the impact until we finish our M&E and see the uptake rates/disease rates change)
👋 which meta-analyses did you look at? I have looked into this a subject a bit and would be curious to read more. Thanks!
I used Abioye, Hajifathalian & Danaei on mass media, and Kang et al on pedometers. We also looked at a bunch of other interventions (e.g. built environment measures, digital interventions, point-of-decision prompts like posters by stairs, etc) - do take a look at Annex A in our CEA for a qualitative discussion of the available intervention options, the relevant evidence base/expert feedback, and why we prioritized government public education campaigns.