026 - A multi-level social network model which accounts for physician movement between hospitals during step-wedge trials

The projection of bipartite networks of patients linked to physicians to a shared-patient physician network allows researchers to study the way the physician ecosystem influences health services. Such networks can be constructed from insurance claims such as in Medicare data or from electronic medical records, etc. Previous research has investigated how these networks associate with patient care, outcomes, as well as research trial outcomes. In this work, we investigate whether the structure of physician-physician networks contains markers that associate with a physician's willingness to participate in a research trial.

At 34 select hospitals across the country, 349 hospitalists associated with Sound Physicians medical working group were asked to participate in clinical research. Of those, 164 (46.99%) agreed to participate. Participants were invited using a step-wedge trial design, between September 1 of 2020 and February 1 of 2021. We identified Medicare claims for 305 (87.39%) of the invited physicians and constructed a unipartite physician network connecting physicians with 15 or more shared patients in 2019.

Due to the COVID-19 pandemic, waves of high-infection rates across the country caused massive disruption to hospital systems and infrastructure.
We hypothesized that physician's movement between hospitals would increase during this period. In addition to the above physician network, we also constructed networks where nodes are hospitals and are connected if they have at least one physician billing at both hospitals. Hence, in this work, we propose a multi-level network methodology which considers both the physician shared-patient network as well as a hospital level shared-physician network.

Networks were built for each month between December 1, 2018 and May 31, 2021 using patient encounters provided by Sound Physicians. We defined the start of pandemic months as March 1, 2020. We found that the during pandemic, hospital networks were more densely connected (p=0.041) and had smaller diameter (p=0.006) reflecting the increase in the extent to which physicians practiced at multiple hospitals.

This dual increase of physician-sharing between hospitals and of physicians practicing at multiple hospitals increases the possibility that hospital-specific attitudes towards research participation may diffuse to hospitals with physician overlap. In ongoing work, we are evaluating the extent to which both physician-level and hospital-level network factors associated with likelihood of trial participation.

The social network of physician colleagues both with hospitals and across hospitals may influence their willingness to participate in research trials. Further study of this phenomenon from a social network perspective may provide insights on how to leverage physician-physician networks to encourage higher rates of research participation.

Social network analysis

Physician sharing networks

Step wedge trials

Multi-level network analysis 

Mid-Level

Knowledge

International Conference on Health Policy Statistics 2023