The ASA Physical Status Classification: Inter-observer Consistency

TLDR

The ASA physical status classification system has been shown to be inconsistently applied by anesthetists. This study examines the validity and usefulness of the ASA system and argues for a more precise scoring system. A survey of 97 Hong Kong specialist anesthetists, based on 10 hypothetical patients, collected ASA assignments and analyzed inter‑observer agreement. Agreement ranged from 31% to 85%, with fair overall correlation (κ 0.21–0.40), and inconsistencies mirrored those seen 20 years ago and were greater between locally and overseas‑trained specialists (P < 0.05).

Abstract

The American Society of Anesthesiologists (ASA) physical status classification system has previously been shown to be inconsistently applied by anaesthetists. One hundred and sixty questionnaires were sent out to all specialist anaesthetists in Hong Kong. Ten hypothetical patients, identical to those of a similar study undertaken 20 years ago, each with different types and degrees of physical disability were described. Respondents were asked about their country of training and type of anaesthetic practice and to assign an ASA classification status for each patient. Ninety-seven questionnaires were returned (61%) after two mailings. Agreement for each patient within groups, between groups and overall comparisons were made. Percentage of agreement was between 31 to 85%. Overall correlation was only fair in all groups (Kappa indices: 0.21–0.4). We found that the current pattern of inter-observer inconsistency of classification was similar to that 20 years ago and exaggerated between locally and overseas trained specialists (P&lt;0.05). The validity of the ASA system, its usefulness and the need for a new, more precise scoring system is discussed.