Co-payments for prescription drugs and the demand for doctor visits--evidence from a natural experiment.

The German health care reform of 1997 provides a natural experiment for evaluating the price sensitivity of demand for physicians' services. As a part of the reform, co-payments for prescription drugs were increased step up to 200%. However, certain groups of people were exempted from the increase, providing a natural control group against which the changed demand for physicians' services of the treated, those subject to increased co-payments, can be assessed. The differences-in-differences estimates indicate that increased co-payments reduced the number of doctor visits by about 10% on an average.