A Coevolution Model of Defensive Medicine, Litigation and Medical Malpractice Insurance

We model the interactions between physicians and patients, subject to clinical and legal risks, by means of an evolutionary game. In each instant of time, there is a large number of random pairwise encounters between members of the two populations. In each encounter, a physician heals a patient. The outcome of the healing process is uncertain and may result in patient harm; if that happens, the patient may sue the physician for medical malpractice. Physicians have to choose between two alternative treatments, D and ND, with different levels of benefits and risks. The treatment D is less risky than the alternative treatment ND, but has the disadvantage of providing a lower expected benefit to the patient. Therefore its provision corresponds to practicing “negative” defensive medicine.