Brown Bag Seminar Industrial Economics

Access to information is vital to physicians who make critical treatment decisions that shape patients' lives. Although formal channels, such as professional training, medical databases, and clinical guidelines, are well-documented, little is known about informal learning, in which physicians acquire knowledge from peers or patients. In this paper, I study how patients act as carriers of clinical information that can influence the treatment behaviors of primary care physicians. When patients switch doctors, they bring with them not only medical histories but also expectations and experiences that can influence their new providers. I investigate whether the treatment styles they experienced at their previous clinics are adopted by their new physicians, thereby indirectly affecting how care is delivered to existing patients. Exploiting the quasi-random reassignment of patients after clinic closures, I find that receiving double the number of patients with antibiotic prescribing history increases the overall antibiotic prescribing intensity at the receiving clinic by 2 percent that cannot be explained by quality change or crowding out. The effect is more pronounced for broad-spectrum antibiotics, where doubling new patients with any type of antibiotic prescribing drives up prescribing by 4 percent. The findings suggest that practice styles, especially low-value prescribing styles,  can dissipate through patient movements. This paper provides novel insights into an informal but potentially impactful channel of medical knowledge diffusion, with practical implications for reducing variations in care quality and improving healthcare equality through better-informed clinical decision-making.