Crystal M. Smith-Spangler, MD; Jessie L. Juusola, MS; Eva A. Enns, MS; Douglas K. Owens, MD, MS; Alan M. Garber, MD, PhD
Sodium consumption raises blood pressure, increasing the risk for heart attack and stroke. Several countries, including the United States, are considering strategies to decrease population sodium intake.
To assess the cost-effectiveness of 2 population strategies to reduce sodium intake: government collaboration with food manufacturers to voluntarily cut sodium in processed foods, modeled on the United Kingdom experience, and a sodium tax.
A Markov model was constructed with 4 health states: well, acute myocardial infarction (MI), acute stroke, and history of MI or stroke.
Medical Panel Expenditure Survey (2006), Framingham Heart Study (1980 to 2003), Dietary Approaches to Stop Hypertension trial, and other published data.
U.S. adults aged 40 to 85 years.
Incremental costs (2008 U.S. dollars), quality-adjusted life-years (QALYs), and MIs and strokes averted.
Collaboration with industry that decreases mean population sodium intake by 9.5% averts 513Â 885 strokes and 480Â 358 MIs over the lifetime of adults aged 40 to 85 years who are alive today compared with the status quo, increasing QALYs by 2.1 million and saving $32.1 billion in medical costs. A tax on sodium that decreases population sodium intake by 6% increases QALYs by 1.3 million and saves $22.4 billion over the same period.
Results are sensitive to the assumption that consumers have no disutility with modest reductions in sodium intake.
Efforts to reduce population sodium intake could result in other dietary changes that are difficult to predict.
Strategies to reduce sodium intake on a population level in the United States are likely to substantially reduce stroke and MI incidence, which would save billions of dollars in medical expenses.
Department of Veterans Affairs, Stanford University, and National Science Foundation.
Sodium restriction lowers blood pressure, which in turn reduces heart disease, but most persons cannot voluntarily reduce their sodium intake. Population strategies, such as voluntary reduction of food sodium content by manufacturers or taxing sodium, may be more effective.
This cost-effectiveness analysis suggests that either population strategy would lead to dramatic decreases in the number of strokes and myocardial infarctions and would save the health system billions of dollars.
The analysis does not account for unintended consequences of reducing sodium, such as a compensatory increase in consumption of calories.
Population strategies to reduce sodium intake could lead to dramatic improvements in health and could save billions of dollars.
The model represents the clinical events that can occur at 1-month intervals. Persons in the well state have never had a heart attack or stroke, whereas persons in the CVD state have a history of heart attack or stroke. During each 1-month period, a person in the well or CVD state is at risk for acute MI, acute stroke, or noncardiac death. Persons remain in the acute MI or acute stroke state for up to 1 month and either die of MI or stroke or move to the CVD state. Persons in the CVD state may not return to the well state. CVD = cardiovascular disease; MI = myocardial infarction.
Appendix Table 1.
Appendix Table 2.
Appendix Table 3.
For collaboration with industry, we plot the estimated effects of a 9.5% decrease in population sodium intake as well as the effects if greater decreases in population sodium intake are achieved (20% and 40%). QALY = quality-adjusted life-year.
Appendix Table 4.
We have plotted the percentage of simulations from the probabilistic sensitivity analysis that achieved different levels of costs savings for collaboration with industry versus doing nothing. For example, there is a 98% chance of any cost savings with collaboration compared with doing nothing, a 78% chance of saving at least $10 billion, and a 40% chance of saving at least $30 billion. The probability of cost savings is the same with and without inclusion of a quality-of-life impairment due to the reduced-sodium diet.
Assume a lifetime quality-of-life impairment with the reduced-sodium diet. For each simulation, the computer selects a set of values from the distribution of each variable in the model and estimates the costs and QALYs for the intervention and the status quo. Incremental costs and QALYs are calculated by subtracting the intervention estimate from doing nothing. This method of sensitivity analysis allows all variables in the model to vary across their estimated distributions with each simulation. The mean reduction of sodium intake for collaboration with industry is 9.5%. The Appendix describes the distributions used. In 54% of simulations, collaboration with industry both saves money and gains QALYs (lower-right quadrant). QALY = quality-adjusted life-year.
Appendix Table 5.
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Smith-Spangler CM, Juusola JL, Enns EA, Owens DK, Garber AM. Population Strategies to Decrease Sodium Intake and the Burden of Cardiovascular Disease: A Cost-Effectiveness Analysis. Ann Intern Med. ;152:481–487. doi: 10.7326/0003-4819-152-8-201004200-00212
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Published: Ann Intern Med. 2010;152(8):481-487.
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