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, 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 policy is directed toward patients, one toward physicians, and one toward both patients and physicians. For each policy, I describe the observable characteristics of patients induced into treatment. Although the policy with the highest return is directed toward patients, the policies differ substantially with respect to the population affected. Therefore, a policy with lower return that targets better the desired population may be preferred to the policy with the highest return.