The economic theory of cost-effectiveness thresholds in health: Domestic and international implications.

Public health insurers often use an implicit or explicit cost-effectiveness threshold to determine which health products and services should be insured. We challenge the convention of a single threshold. For competitively provided products and services, prices are determined by cost; but for products with market power, patentees will increase the price according to the perceived threshold. As a result, a change in the threshold affects the prices of all patented products, including those which would have been developed even at a lower threshold. The insurer can increase efficiency by reducing the threshold for patented products, even accounting for the effect on innovation. We also model a multi-country setting, in which thresholds for patented products will fall below the globally cooperative solution because each country does not recognize the positive externality of its own spending on innovative medicines. We show that this tragedy of the commons problem can be partly corrected through referencing other countries' thresholds, but only when the countries have similar willingness to pay.