Cost-Effectiveness of Interventions
Only a few studies have described interventions for lifestyle diseases in developing countries.
Modeling Likely Interventions
Primary targets for reducing lifestyle diseases include changing the fat composition of the diet, limiting sodium intake, and engaging in regular physical activity.
Using available data, we calculated a range of estimates under given assumptions for the cost-effectiveness of replacing dietary saturated fat with monounsaturated fat, replacing trans fat with polyunsaturated fat, and reducing salt intake. An increase in moderate physical activity by three to five hours per week is considered likely to lower the risk of many diseases, but data to model the cost-effectiveness of this intervention are not currently available. For further details of methods and assumptions underlying the analyses presented here, see the Web site version of this book.
Reducing Saturated Fat Content
In the base case, assuming a 3 percent drop in cholesterol and a US$6 per person cost of the intervention, averting one disability-adjusted life year (DALY) would cost as little as US$1,865 in South Asia and as much as US$4,012 in the Middle East and North Africa. The intervention's effectiveness could be increased by replacing part of the saturated fat with polyunsaturated fat, which has additional beneficial effects mediated by mechanisms other than LDL cholesterol (see tables 44.2 and 44.3).
Replacing Dietary Trans Fat from Partial Hydrogenation with Polyunsaturated Fat
We could not use the model for saturated fat to estimate the effects of replacing trans fat with polyunsaturated fat because only a small part of the benefit is attributable to reducing LDL cholesterol (F. B. Hu and Willett 2002). Trans fats also adversely affect high-density lipoprotein (HDL) cholesterol, triglycerides, endothelial function, and inflammatory markers. In addition, increases in polyunsaturated fat (assuming a mix of N-6 and omega-3 fatty acids) will reduce LDL cholesterol, insulin resistance, and probably fatal cardiac arrhythmias.
In calculations that are based only on the adverse effects on LDL and HDL, replacing 2 percent of the energy from trans fat with polyunsaturated fat was estimated to reduce CAD by 7 to 8 percent (Grundy 1992; Willett and Ascherio 1994). Epidemiological studies, which include the contributions of the additional causal pathways, suggest a much greater reduction, from about 25 to 40 percent (F. B. Hu and others 1997; Oomen and others 2001). Another likely benefit is a reduction in the incidence of type 2 diabetes: estimates indicate that the same 2 percent reduction would reduce incidence by 40 percent (Salmeron and others 2001).
Because voluntary action by industry (as has nearly been achieved in the Netherlands) or by regulation (as occurred in Denmark) can eliminate partially hydrogenated fat from the diet, this initiative does not require consumer education, and the costs can be extremely low. In an analysis required before implementing food labeling, the U.S. Food and Drug Administration (2003) estimated that trans fat labeling would be highly cost-effective. Even though the effect of labeling itself was estimated to have only a modest effect on consumer behavior, as noted earlier, it is having a major effect on manufacturers' behavior.
The potential for reducing CVD rates by replacing trans fats with polyunsaturated fats will depend on the diets of specific populations. Whereas the intake of trans fat is low in China, it is likely to be high in parts of India, Pakistan, and other Asian countries because of the extraordinarily high content in commonly used cooking fats.
Table 44.2 presents the results of a cost-effectiveness analysis assuming the two different estimates for CAD reduction: 7 percent and 40 percent. We used costs of US$0.50 per adult per year, which was the maximal cost in the U.S. Food and Drug Administration analysis, and of US$6.00 per adult per year using traditional health education approaches. The lower estimate—or one even lower—is possible because trans fat can be eliminated at the source rather than depending entirely on changes in individual behavior. With the lower cost, the smaller effect estimate leads to a cost-effectiveness ratio of between US$25 and US$73 per DALY averted, depending on the region, and with the higher-effect estimate, the intervention can be cost saving.
Reducing the Salt Content of Manufactured Foods through Legislation and an Accompanying Education Campaign
Table 44.2 shows the base-case cost-effectiveness of a legislated reduction in salt content. The intervention appears to be relatively cost-effective, with a cost per DALY averted of US$1,325 in South Asia to US$3,056 in the Middle East and North Africa. Those regional variations are attributable to differing risk profiles across regions as well as to price differentials for the costs of treating disease sequelae.
The actual blood pressure reduction from lower salt consumption could vary from the base-case assumption, as could the costs of the education campaign. Table 44.4 shows the results of lower costs of the education campaign and higher or lower effects of the intervention on blood pressure. These results may argue for initial efforts to focus on reductions in the use of salt during the manufacturing process with no public education campaign. The cost-effectiveness of such a change is high and could be augmented with a public education campaign only if needed to support the legislated change. At lower implementation costs, the intervention is highly cost-effective, even with half the assumed effect on blood pressure.
Adopting Physical Activity Interventions
Even though health experts believe that physical activity interventions are effective in reducing the risk of lifestyle diseases, no studies of their cost-effectiveness are available from developing countries. If people walk voluntarily (the model assumes no opportunity cost), a net economic benefit would accrue to all segments of the U.S. population. If we project the economic benefits to the entire U.S. population and assume 25 percent compliance by the sedentary population, the voluntary program would generate US$6.8 billion in savings (in 2001 U.S. dollars).
Aggregate Costs of Obesity and Unhealthy Lifestyles
A series of U.S. studies appears to confirm that the avoidable costs of chronic diseases are substantial, although many developing countries have not yet experienced the full demands on their health sectors resulting from these conditions. Colditz (1999) estimates that obesity is responsible for 7 percent of all U.S. direct health care costs and that inactivity is responsible for an additional 2.4 percent of all health care costs. Indirect costs associated with obesity and inactivity account for another 5 percent of health care costs. Pronk and others (1999) assess the difference in health care costs between adult patients with and without risk factors for noncommunicable diseases (physical activity, BMI, and smoking status) and find that a healthier lifestyle of physical activity three times per week, a moderate BMI, and nonsmoking status reduce health care costs by 49 percent compared with an unhealthy lifestyle.
Cost-Effectiveness of Community-based Interventions
Populationwide and community-based interventions appear to be cost-effective if they reach large populations, address high-mortality and high-morbidity diseases, and are multipronged and integrated efforts. The full costs of achieving changes in behavior and policy are often complex and difficult to estimate. Interventions may yield additional spinoff benefits. For instance, decisions to reduce children's television viewing could easily improve school outcomes as well as reduce childhood obesity. Similarly, increasing walking and bicycle riding for transportation could reduce air pollution.