Purpose: Reduced sodium consumption lowers high blood pressure, which is a major risk factor for heart attack and stroke. Several countries, therefore, are considering strategies to decrease population sodium intake. We examined the cost-effectiveness of two strategies to reduce dietary sodium intake among US adults: 1) government collaboration with food manufacturers to cut sodium in processed foods and 2) a salt tax.
Method: We developed a Markov state transition model, estimating transition probabilities using published data from the Framingham Heart Study and other sources. Disease states modeled were acute myocardial infarction (MI), acute stroke, “well” (no history of MI or stroke), and “CVD” (history of MI or stroke). Adults aged 40-85 years entered the model either in the well or CVD state. Direct medical costs were assessed from a societal perspective and utilities estimated from the published literature. For the base case analysis, we estimated that a strategy of collaboration with industry to cut sodium in food would cost $0.1/per person/month and decrease sodium intake by 9.5%, based on the UK’s experience with this strategy. A salt tax that increased the cost of salty foods by 40% was estimated to decrease sodium intake by 6% with negligible costs. Future costs and benefits were discounted at 3%.
Result: Over 10 years, collaboration with industry to cut sodium in processed foods averts 232,860 strokes and 272,662 MIs, gains 434,209 QALYs, and saves society $11B. The tax on salt averts 150,411 strokes, 176,867 MIs, gains 155,526 QALYs, and saves society $8B. Most of the cost savings are from fewer people entering the CVD state, not from the cost of acute events. Industry collaboration yields more QALYs at a lower cost compared to the tax because we assume industry collaboration is more effective at cutting sodium intake than the tax. The two strategies could be combined to achieve greater benefits. The results are most sensitive to cost of CVD state, though both strategies remain cost saving when varying medical costs in the well and CVD state across plausible ranges.
Conclusion: Strategies to reduce sodium consumption on a population level are likely to be cost saving and increase QALYs. Industry collaboration to cut sodium in processed foods and a salt tax could be combined for greater benefits.
Candidate for the Lee B. Lusted Student Prize Competition