Categorical measurements of subjectiveness: is there still a role for the ASA classification? - Critical Care Science (CCS)
In 1941, Saklad proposed a classification system that attempted to assess and measure a patient’s physiologic reserve before a surgical procedure.() After undergoing a few modifications, it became widely known as the American Society of Anesthesiologists (ASA) physical status classification system.() It became widely used and became part of the routine pre-operative assessment in many countries (it is also used for billing reasons in the United States).() It is an apparently simple classification system that has been frequently shown to be associated with morbidity and mortality.
The ASA classification system was revolutionary in its field.() Contrary to modern prognostic scores,(,) the ASA relies on an apparently simple principle: outcome depends on the patient’s previous comorbidities and how those comorbidities affected the patient. If comorbidities affect the patient’s physiologic reserve, then less remains for withstanding surgical stress. As statistics interweaved into medicine, prognostication began to rely on more objective, “palpable” features. As a result, none of the most commonly used severity indexes applied in the modern intensive care units setting incorporate any measure of previous performance status,(,) despite the fact that performance status has been repeatedly shown to be have prognostic significance.(,) Even scoring systems aimed at predicting morbidity after surgery, such as POSSUM, P-POSSUM and SORT,(,) fail to account for performance status. There are some reasons for this. First, objective measurements are less prone to personal and local bias. For example, heart rate assessment is performed in the same manner everywhere, as is the case for blood pressure, pH, etc. In contrast, the ASA score varies widely from person to person, as it is subjective. Therefore, it is not surprising that the agreement between ASA scores obtained by different physicians and between ASA scores obtained at different time points is only moderate.(,)
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In 1941, Saklad proposed a classification system that attempted to assess and measure a patient’s physiologic reserve before a surgical procedure.() After undergoing a few modifications, it became widely known as the American Society of Anesthesiologists (ASA) physical status classification system.() It became widely used and became part of the routine pre-operative assessment in many countries (it is also used for billing reasons in the United States).() It is an apparently simple classification system that has been frequently shown to be associated with morbidity and mortality.
The ASA classification system was revolutionary in its field.() Contrary to modern prognostic scores,(,) the ASA relies on an apparently simple principle: outcome depends on the patient’s previous comorbidities and how those comorbidities affected the patient. If comorbidities affect the patient’s physiologic reserve, then less remains for withstanding surgical stress. As statistics interweaved into medicine, prognostication began to rely on more objective, “palpable” features. As a result, none of the most commonly used severity indexes applied in the modern intensive care units setting incorporate any measure of previous performance status,(,) despite the fact that performance status has been repeatedly shown to be have prognostic significance.(,) Even scoring systems aimed at predicting morbidity after surgery, such as POSSUM, P-POSSUM and SORT,(,) fail to account for performance status. There are some reasons for this. First, objective measurements are less prone to personal and local bias. For example, heart rate assessment is performed in the same manner everywhere, as is the case for blood pressure, pH, etc. In contrast, the ASA score varies widely from person to person, as it is subjective. Therefore, it is not surprising that the agreement between ASA scores obtained by different physicians and between ASA scores obtained at different time points is only moderate.(,)
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