Hospital Volume and Operative Mortality for General Surgery Operations Performed Emergently in Adults

Abstract and Introduction

Abstract

Objective: This study aimed to answer 2 questions: first, to what degree does hospital operative volume affect mortality for adult patients undergoing 1 of 10 common emergency general surgery (EGS) operations? Second, at what hospital operative volume threshold will nearly all patients undergoing an emergency operation realize the average mortality risk?

Background: Nontrauma surgical emergencies are an underappreciated public health crisis in the United States; redefining where such emergencies are managed may improve outcomes. The field of trauma surgery established regionalized systems of care in part because studies demonstrated a clear relationship between hospital volume and survival for traumatic emergencies. Such a relationship has not been well-studied for nontrauma surgical emergencies.

Methods: Retrospective cohort study of all acute care hospitals in California performing nontrauma surgical emergencies. We employed a novel use of an ecological analysis with beta regression to investigate the relationship between hospital operative volume and mortality.

Results: A total of 425 acute care hospitals in California performed 165,123 EGS operations. Risk-adjusted mortality significantly decreased as volume increased for all 10 EGS operations (P < 0.001 for each); the relative magnitude of this inverse relationship differed substantially by procedure. Hospital operative volume thresholds were defined and varied by operation: from 75 cases over 2 years for cholecystectomy to 7 cases for umbilical hernia repair.

Conclusions: Survival rates for nontrauma surgical emergencies were improved when operations were performed at higher-volume hospitals. The use of ecological analysis is widely applicable to the field of surgical outcomes research.

Introduction

Inadequate timely availability of definitive operative interventions for patients with nontrauma surgical emergencies in the United States has been termed a "crisis" in emergency surgical care (ESC).^[1–3] The scope of this crisis is on par with major medical conditions considered public health problems, including diabetes mellitus, coronary artery disease, and cancer.^[4] The lack of access to decisive surgical treatment for readily curable surgical diagnoses has worsened over time, driven by the growing, aging US population and the increasing shortage of surgeons to cover emergency operations.^[5,6] Multiple surgical and medical organizations in the United States have expressed the need to find solutions to the ESC crisis, but as of now, no consensus decision or recommendation has been made.^[1–3,7]

One potential solution is the complete restructuring of emergency surgical systems of care in the United States, which would include changing how such emergencies are triaged and redefining when and where they are managed. Such a drastic departure from our current systems of delivery for surgical care must be empirically driven, but to date there is little direct evidence to support or initiate such change. It was exactly such evidence that catalyzed the regionalization of trauma surgery 35 years ago, and trauma systems continue to mature, evolve, and be investigated today.^[8–15]

One body of research which helped to validate the creation of regionalized trauma systems was establishing that there is a clear relationship between the volume of trauma patients a hospital treats and its outcomes for those patients.^[16–18] To date, however, there conflicting studies on the importance of the hospital volume-to-outcomes relationship for emergency general surgery (EGS) operations.^[19,20] Establishing this relationship could lead to data-driven support for the restructuring and regionalization of the entire system of ESC and potentially improve outcomes.

Volume-outcome relationships have been studied extensively in patients having elective, nonemergent operations. This research has shown that increased hospital operative volume^[21–27] and increased individual surgeon volume^[27–29] leads to better outcomes. These relationships have been generalized to exist for emergent operations. This generalization, however, may not be valid, as the EGS patient population is vastly different from its elective counterpart.^[30,31]

This study aimed to answer 2 questions: first, to what degree does hospital operative volume impact mortality for adult patients undergoing 1 of 10 common EGS operations? Second, at what hospital operative volume threshold will nearly all patients undergoing an emergency operation realize the average mortality risk? We hypothesized that increased hospital volume would be associated with decreased mortality across a range of 10 emergency operations, and that this inverse relationship would cross a volume threshold beyond which there was a very high likelihood that an institution was performing at or above the average mortality rate.

Annals of Surgery. 2020;272(2):288-303. © 2020 Lippincott Williams & Wilkins