That is something that hasn't been studied much. There are estimates, but so far the results differ greatly.
For example, some studies in the United States show that if more drugs were covered by the plan, there would be fewer hospitalizations. In fact, this argument is being used to state that more and more new drugs should be covered. However, the reality is something very different. The number of hospitalizations is significantly lower when there is greater access to drugs, particularly for lower-income individuals.
It is clear that the costs will drop when patients better follow their treatment. We see it fairly systematically, even though it sometimes means fewer choices when it comes to drugs. A new study—and I can send you a copy—was recently published by CVS, an American chain of pharmacies. It shows that, in terms of health outcomes, using a more restrictive formulary to reduce costs can make access to some drugs more difficult for certain patients. That creates a problem. Moreover, health outcomes are improved through better adherence to treatment than for other patients.
So a more limited formulary does not have an impact on the overall population, but can make a difference in specific cases.