Note: This report has been superseded by our subsequent Deep Report on Hypertension - please browse that report for our most updated findings.
Taking into account the expected benefits of eliminating hypertension (i.e. improved health and increased economic output), as well as the tractability of policy advocacy for a sodium tax as well as various World Health Organization (WHO) Best Buy interventions (i.e. mandatory food reformulation; location-based interventions, a public education and mass media campaign, and mandatory front-of-pack labelling), CEARCH finds that the marginal expected value of policy advocacy for these top sodium control solutions to eliminate hypertension to be 49,419 DALYs per USD 100,000, which is around 80x as cost-effective as giving to a GiveWell top charity (CEA).
The full 32-page report may be found on CEARCH's website (report); this post is a high-level summary intended for busy forum readers who are definitely not browsing the forum when they should actually be working.
- Importance: This is a strongly important cause, with 2.51 * 1010 DALYs at stake from now to the indefinite future. Around 65% of the burden is health related, while 35% is economic in nature.
- Neglectedness: The present global disease burden of hypertension is expected to grow as a result of various factors – especially economic growth (which causes a shift to western pattern diets and sedentary lifestyles), ageing (since older individuals are intrinsically at greater risk of hypertension) and population growth. At the same time, governments are doing little to solve the problem, with only 5% of countries implementing the WHO's Best Buy solutions for hypertension. This is unlikely to change much going forward, as governments have been introducing these effective policies at a rate of 0.8% per annum so far.
- Tractability: A solution with moderate tractability is available, in the form of policy advocacy for sodium taxes and the WHO's Best Buy solutions. While the chances of policy advocacy for such sodium control is fairly low, the empirical literature strongly and unequivocally supports the idea that such interventions will help reduce sodium intake and that lower sodium intake will in turn reduce the disease burden of hypertension.
- Beyond the headline CEA results, it can be valuable to use cluster thinking (i.e. looking at the issue from multiple perspectives) to inform our decision on whether to channel resources towards a cause area – as CEAs are sensitive to errors, and multiple perspectives offer a way to robustly sense check our quantitative estimate. Employing this cluster view, and looking at the quality of evidence, expert opinion, and multiple critical considerations, CEARCH finds that hypertension as a cause area does indeed look extremely promising.
- Quality of Evidence: Overall, the evidence suggests that the intervention is an effective one. For more details, refer to the Tractability section in the report; but here is a brief summary:
- Success rate of sodium control policy advocacy: Using both an outside view (e.g. of past sodium and sugar tax advocacy attempts and of general lobbying attempts) as well as an inside view, our best guess is that policy advocacy for sodium control has a 3% chance of success.
- How sodium control policy affects sodium consumption: Based on the various systematic reviews and meta-analysis, and after robust discounts and checks (e.g. for a conservative theoretical prior of a null hypothesis; for publication bias; and for miscellaneous issues like reporting bias, endogeneity & selection bias), we expect sodium control policy to significantly reduce sodium consumption as follows: (a) sodium tax (-134 mg/day); (b) mandatory food reformulation (-385 mg/day); (c) location-based intervention (-166 mg/day); (d) public education and mass media campaign (-131 mg/day); and (e) mandatory front-of-pack labelling (-135 mg/day).
- How sodium consumption affects health: Similarly, various meta-analysis – even after the same sort of robust discounts and checks employed above – suggest that sodium intake significantly reduces resting systolic blood pressure (n.b. Aburto et al: -3.39 mm Hg); that lower systolic blood pressure reduces cardiovascular risk (n.b. Ettehad et al: every 10 mm Hg fall in BP sees a reduction in risk of major cardiovascular disease events given a relative risk – RR – of 0.8, of coronary heart disease given RR 0.83, of stroke given RR 0.73, and of heart failure to given RR 0.73, leading to a significant 13% reduction in all-cause mortality); and that additional sodium consumption leads to greater risk of CVD (n.b. Strazzullo et al: increase in RR to 1.14 per additional 1880 mg/day of sodium).
- Expert Opinion: The experts we consulted agreed that the global disease burden of hypertension is expected to grow in the coming decades, and that preventive solutions – of the sort the WHO recommends and which we assess here – are generally preferable to treatment. For more details, refer to the discussion on the growth of the problem in the Expected Benefit: Improved Health from Eliminating Hypertension section of the report, and to the discussion on potential solutions in the Problem & Solution section.
- Multiple Considerations: Beyond the major considerations (i.e. importance, neglectedness and tractability) – as already discussed above, and which hypertension as a cause area scores well on – hypertension also looks promising given various miscellaneous considerations. In particular, we find that potential lines of criticism (e.g. whether sodium control policy leads to substitution with respect to home foods or to sugary food; or whether we pay too heavy a price with respect to diminished freedom of choice and food pleasure; or whether a sodium tax in particular is regressive) are not sustained. For more details, refer to the Miscellaneous Considerations section of the report.
- The marginal expected value of hypertension as a cause area for effective altruism has dropped from 300x GiveWell at the shallow research stage to 80x GiveWell here (i.e. an almost 4x drop). Here are some of the factors that caused that drop, or that – conversely – led the drop to not be as large as it would otherwise have been.
- An important pair of discounts absent at the shallow research stage but introduced here are: (a) for governments' current sodium policy capturing some of the future benefit; and (b) for governments' future sodium policy (i.e. the mere speeding-up effect).
- We have updated our modelling of the future disease burden to linearly project forward the trend in DALY burden per capita, and then applying the results to UN figures on global population up to 2100. This is in contrast to our previous approach of a multiple regression of total DALY burden on age-standardized DALY burden per capita, population size, and median age, to find the relevant coefficients, and then projecting forward based on the linear trends in the underlying variables. Our updated model, we believe, is both more conceptually sound and less counterintuitive in terms of the results it produces. Overall, our updated modelling suggests a higher future disease burden than initially expected.
- We have downgraded our confidence in the success rates of sodium policy advocacy.
- However, given that the intervention being assessed is no longer just a sodium tax but multiple effective sodium control policies – which makes sense, insofar as advocates can push more than one policy at a time, when engaging governments – our tractability figures do get a boost.
- Possibly the biggest single driver of the fall in the headline MEV is our far more pessimistic costing, especially since we have re-evaluated the likely amount of time needed for lobbying to succeed (or to evidently fail in such a way as to warrant a shutdown or pivot) as 3 years, rather than just 1.
- Point estimates are sensitive, and while relying on them is reasonable given that we are ultimately interested in mean estimates, caution is also warranted.
- On top of the initial shallow research round where one week of desktop research was conducted, this intermediate research round saw two weeks of desktop research and expert interviews carried out. We have reasonable confidence in our results here, but more research at the deep stage will be needed before we will have high confidence in these findings.
- The headline cost-effectiveness will almost certainly fall if this cause area is subjected to deeper research: (a) this is empirically the case, from past experience; and (b) theoretically, we suffer from optimizer's curse (where causes appear better than the mean partly because they are genuinely more cost-effective but also partly because of random error favouring them, and when deeper research fixes the latter, the estimated cost-effectiveness falls). As it happens, CEARCH intends to perform deeper research in this area, given that the headline cost-effectiveness meets our threshold of 10x that of a GiveWell top charity.
The full 32-page report may be found on CEARCH's website (report).