Estimating the effect of familiarity in surgical teams on procedure time under a causal graphical model

This study estimates the causal impact of surgical team familiarity on surgery duration across various procedures in a hospital, under an assumed Directed Acyclic Graph (DAG) structure. While existing literature indicates that greater familiarity among surgical team members, measured by their shared work experience, is linked to reduced surgery times, these studies typically focus on a specific type of surgical procedure and only suggest a correlational relationship. Our study is the first to examine the hospital-wide relationship between surgical team familiarity and procedure duration using a formal causal inference framework. To explore this relationship, team familiarity is measured based on interaction frequency, and data across procedures are standardized to facilitate analysis via structural causal modeling and regression analysis. An analysis of 33,374 procedures performed in a high-volume academic medical center in the US from January 2017 to November 2023 reveals a negative causal relationship between surgeon-scrub familiarity and surgery duration under our DAG assumptions. Specifically, increasing familiarity by one standard deviation leads to a reduction of 1.9 to 3.7 minutes in surgery duration. Similar, albeit smaller, effects are observed for surgeon-circulator familiarity, whereas no significant impact is found for scrub-circulator familiarity. To our knowledge, this is the first study to estimate the causal effect of surgical team familiarity across an entire hospital's surgical portfolio under the assumptions of a DAG, moving beyond prior correlational analyses limited to specific specialties or methods. Ultimately, the study reveals that improving team familiarity, particularly between surgeons and scrub nurses, could hold significant implications for improving surgical team efficiency. This is especially relevant in high-volume hospitals, where even minor time savings can accumulate significantly, underscoring the value of leveraging team familiarity to optimize performance in hospital operating rooms.