Correlation of ASA Scale with Complications, Outcomes, and Revision

The American Society of Anesthesiologists (ASA) physical status scale is a classification tool to estimate a patient’s physical fitness before surgery [1]. It was introduced in 1941 and has undergone modifications in 1961, 1980, and 2014. Initially, there were four classes of physical fitness and two extra classes for emergency surgery, illustrated by examples to improve correct classification. In the original ASA scale, ASA 1 was ‘no organic pathology, or a patient in whom the pathological process is localized and does not cause any systemic disturbance or abnormality’. ASA 2 was ‘a moderate but definite systemic disturbance, caused either by the condition that is to be treated by surgical intervention or which is caused by other existing pathological processes’. ASA 3 denotes ‘severe systemic disturbance from any cause or causes; the severity is a matter of clinical judgement’. ASA 4 was reserved for ‘extreme systemic disorders which have already become an imminent threat to life regardless of treatment’; this class was intended for patients in extremely poor physical state. Classes 5 and 6 were for ASA 1–2, resp. 3–4 in need of emergency surgery.