Global assessment of surgical skills (GASS): validation of a new instrument to measure global technical safety in surgical procedures

Abstract

Background: Broad implementation of the American Board of Surgery's entrustable professional activities initiative will require assessment instruments that are reliable and easy to use. Existing assessment instruments of general laparoscopic surgical skills have limited reliability, efficiency, and validity across the spectrum of formative (low-stakes) and summative (high-stakes) assessments. A novel six-item global assessment of surgical skills (GASS) instrument was developed and evaluated with a focus upon safe versus unsafe surgical practice scoring rubric.

Methods: The GASS was developed by iterative engagement with expert laparoscopic surgeons and includes six items (economy of motion, tissue handling, appreciating operative anatomy, bimanual dexterity, achievement of hemostasis, overall performance) with a uniform three-point scoring rubric ("poor-unsafe", "adequate-safe", "good-safe"). To test inter-rater reliability, a cross-sectional study of four bariatric surgeons with experience ranging from 4 to 28 years applied the GASS and the global operative assessment of laparoscopic skills (GOALS) to 30 consecutive Roux-en-Y gastric bypass procedure operative videos. Inter-rater reliability was assessed for a simplified dichotomous "safe" versus "unsafe" scoring rubric using Gwet's AC₂.

Results: The GASS inter-rater reliability was very high across all six domains (0.88-1.00). The GASS performed comparably to the GOALS inter-rater reliability scores (0.96-1.00). The economy of motion and bimanual dexterity items had the highest percentage of unsafe ratings (9.2% and 5.8%, respectively).

Conclusion: The GASS, a novel six-item instrument of general laparoscopic surgical skills, was designed with a simple scoring rubric (poor-safe, adequate-safe, good-safe) to minimize rater burden and focus feedback to trainees and promotion evaluations on safe surgical performance. Initial evaluation of the GASS is promising, demonstrating high inter-rater reliability. Future research will seek to assess the GASS against a broader spectrum of laparoscopic procedures.

Keywords: Clinical competence; Gastric bypass; General surgery; Process assessment, health care; Surgical procedures, operative; Video tape recording.