The American Society of Anesthesiologists physical status (ASA-PS) classification system is used worldwide to classify patients based on comorbid conditions before general anesthesia. Despite its popularity, the ASA-PS classification system has been shown to have poor interrater reliability due to its subjective definitions, especially when applied to the pediatric population. We hypothesized that the clarification of ASA-PS definitions to better reflect pediatric conditions would improve the accuracy of ASA-PS applied to this population.
A stratified, randomized sample of 120 pediatric surgical cases was collected from a tertiary-care pediatric hospital. A team of senior anesthesiologists reclassified ASA-PS within this patient sample using the suggested pediatric-specific ASA-PS definitions. Interrater reliability was measured using intraclass correlation (ICC) and Fleiss κ statistic. In addition, a qualitative study component using small focus groups of senior anesthesiologists identified areas of ambiguity within the ASA-PS system.
Among the 90 reclassifications within each ASA-PS group, 42.2% (n = 38) of ASA-PS I were upgraded to ASA-PS II, and 36.7% (n = 33) of ASA-PS II were upgraded to ASA-PS III. In addition, 28.9% (n = 26) of ASA-PS III were upgraded to ASA-PS IV, and 24.4% (n = 22) of ASA-PS IV were downgraded to III. ICC across the reclassified ASA-PS categories was 0.77 (95% confidence interval [CI], 0.71–0.83; P < .001) demonstrating strong overall agreement. Fleiss κ statistic was lowest in ASA-PS II and III patients (κ = 0.41 and κ = 0.30, respectively) indicating lower agreement beyond chance within these subgroups. Focus groups revealed common themes such as active sequelae of disease, active versus well-controlled presence of comorbidities, and the possible inclusion of functional limitations as important considerations.
The ASA-PS classification system has several benefits including ease-of-use, simplicity, and flexibility. However, revising the ASA-PS system to provide better guidance for pediatric patients could be valuable. While this study demonstrates good interrater reliability with the included ASA-PS pediatric definitions, further work is needed to clarify accurate assignment of ASA-PS within the midrange of the scale (ASA-PS II and III) and explore its implementation in other institutions.
From the *Department of Anesthesiology, Critical Care and Pain Medicine
†Complex Care Service, Division of General Pediatrics, Boston Children’s Hospital, Boston, Massachusetts.
Accepted for publication May 7, 2019.
The authors declare no conflicts of interest.
Reprints will not be available from the authors.
Address correspondence to Lynne R. Ferrari, MD, Department of Anesthesiology, Critical Care and Pain Medicine, Boston Children’s Hospital, 300 Longwood Ave, Boston, MA 02115. Address e-mail to firstname.lastname@example.org.