Professional norms and physician behavior: Homo oeconomicus or homo hippocraticus?

Professional norms such as the Hippocratic Oath have governed physician practice since ancient times. In this paper, we address the question of how professional norms affect the trade-offs of physicians between their own profit, the patient, and the cost of medical care to society as a whole. There exists no reliable empirical evidence on this question, and it is unlikely that observational studies will be able to uncover causal relationships. We therefore employ a controlled experiment to study the behavior of individuals in a situation in which decisions and incentives resemble those of physicians. Our subjects are 132 medical students from two large German universities.

Specifically, our novel experimental task allows us to observe how subjects trade off between three quantities: their own profit; the payoff of a receiver (the patient); and the contributions of a group of payers (the taxpayer or the collective of insured individuals). The task is designed so that we can manipulate the efficiency of the payment mechanism, which translates the sum of contributions into the decider's and receiver's payoffs. We then adopt a conceptual priming approach and augment the experimental task with randomized treatments that vary the salience of the Hippocratic Oath as a professional norm. Before seeing the choice task, all subjects answer a questionnaire on their socio-economic background and their occupational choice. At the end of this survey, one third of our subjects are shown a modern version of the Hippocratic Oath embedded in a survey question. In the control group (two thirds of the subjects), this particular question is not asked (while the overall length of the survey is roughly the same). This research design allows us to separate the impact of professional norms on deciders' behavior from that of other-regarding preferences for receivers and payers.

Each subject plays 12 distributional games. We find that subjects strongly react to financial incentives. They show concerns for both the receiver's payoff as well as the costs to the payers. The size of the effects are strongest for the own payout, weaker for the receiver, and weakest for the payers. We also find sizeable effects of the professional norm manipulation: There is a strong positive effect of the Hippocratic Oath on the average amount of the good provided. This implies that the professional norm benefits the receiver (the patient) and harms the payer (society). It reduces the deciders' degree of selfishness. Finally, the relative increase in the good’s provision under the Hippocratic Oath is larger when it is more inefficient to provide the good.

These are striking results - they highlight that prospective physicians, just like individuals in many experimental studies before, exhibit a combination of selfish and other-regarding preference, and that they detect efficiency losses and aim to reduce then. Importantly, however, all these effects are dampened by a professional norm that puts all the weight on the receiver (the patient).