• Journal: JAMA Surgery

• PMID: 35857304

• Type of study: Retrospective cohort study

• Objective

  • To evaluate the association between anesthesiologist staffing ratios and surgical patient morbidity and mortality

• Methods

  • Retrospective cohort study

  • Used MPOG Database

    • Multicenter Perioperative Outcomes Group

  • Population

    • > 18 years old

    • Team-model (anesthesiologist supervising CRNAs)

    • General anesthesia

    • 2010 - 2017

    • Exclusions

      • Cases with > 25% resident involvement (due to required staffing ratio of 1:2 or 1:1)

      • Cases with anesthesiology assistants

      • Cardiac surgery, liver transplant, cataracts, OB procedures

      • Night/weekend cases

  • Staffing coverage divided into 4 groups using time-weighted average

    • 1 (1 anesthesiologist covering 1 case)

    • 1-2 (>1 to no more than 2 cases covered at the same time)

    • 2-3 (>2 to no more than 3 cases covered at the same time)

    • 3-4 (>3 to no more than 4 cases covered at the same time)

  • Composite outcome

    • 30-day mortality + 6 classes of morbidity

      • Cardiac

      • Respiratory

      • GI

      • Urinary

      • Bleeding

      • Infectious

• Results

  • Increasing staffing ratios was associated with increased postoperative morbidity and mortality

    • Compared to the 1-2 group, the 2-3 group had a 4% relative increase and the 3-4 group had a 14% relative increase in morbidity and mortality

• Strengths

  • MPOG database

  • Large # of subjects

  • Propensity score matching 

  • Generalizable to major health centers in USA

• Weaknesses

  • Non-randomized

  • Questionable generalizability to non-CRNA supervision types of practice

  • Did not include CRNA level of skill/years of practice 

  • Exclusion of resident data

  • Exclusion of important surgeries

  • Lacked specificity on outcomes 

• Key Point: A higher number of ORs concurrently covered by an anesthesiologist is associated with increased morbidity and mortality

JAMA Surg. 2022 Jul 20:e222804