Explaining the causal effect of adherence to medication on cholesterol through the marginal patient

This paper investigates the relation between adherence to prescribed medication and reduction of cholesterol in Italy, by taking into account the possible sorting of patients into treatment and the heterogeneity of the effect. As predicted by a theoretical model, I find that patients who benefit most from medication are more likely to adhere to prescribed regime than those who benefit least. These results are used to study the effects of three hypothetical policies that aim at increasing the share of patients adherent to prescribed medication: one is directed towards patients, one towards physicians, and one is a policy mix. For each policy, the observable characteristics of patients switched into treatment are described. Although the most effective policy is directed towards patients, the policies differ substantially with respect to the population affected. Therefore, a less effective policy that targets best the desired population may be preferred to the most effective policy. Back of the envelope calculations suggest that even the most expensive policy would be cost-effective.