ASA Physical Status Classification System - Limitations and Proposed Modifications

Limitations and Proposed Modifications

These definitions appear in each annual edition of the ASA Relative Value Guide. There is no additional information that can be helpful to further define these categories. It is logical to expect a missing class between ASA 2 and ASA 3 for a systemic disease which is neither mild nor severe, but is of moderate nature. It is also not clear what will be the ASA classification of a patient who is suffering simultaneously from two, three or more systemic diseases (which might be of different severity).

Different authors give different versions of this ASA definition. It is because this classification is vague and far from perfect. Many authors try to explain it on the basis of 'functional limitation' or 'anxiety' of patient which are not mentioned in the actual definition. Often different anesthesia providers assign different grades to the same patient. The word 'systemic' in this classification creates a lot of confusion. For example, heart attack (myocardial infarction), though grave, is a 'local' disease and is not a 'systemic' disease, so a patient with recent (or old) heart attack, in the absence of any other systemic disease, does not truly fit in any category of the ASA classification, yet has poor post-surgery survival rates. Similarly cirrhosis of the liver, COPD, severe asthma, peri-nephric abscess, badly infected wounds, intestinal perforation, skull fracture etc. are not systemic diseases. These, and other severe heart, liver, lung, intestinal or kidney diseases, although they greatly affect physical status of patient and risk for poor outcomes, cannot be labelled as “systemic disease” (which means a generalized disorder of the whole body like hypertension or diabetes mellitus). Local diseases can also change physical status but has not been mentioned in ASA classification.

This classification system assumes that age of the patient has no relation to physical fitness, which is not true. Neonates and the elderly, even in the absence of any systemic disease, tolerate otherwise similar anesthetics poorly in comparison to young adults. Similarly this classification ignores patients with malignancy (cancer). This classification system could not be improved to a more elaborated and scientific form, probably because it is often used for cost reimbursement.

Although more complex scoring systems like APACHE II exist, they are time-consuming to calculate, and do not have the same utility for ease of communication between surgeons, anesthesiologists, and insurers.

Some anesthesiologists now propose that like an 'E' modifier for emergency, a 'P' modifier for pregnancy should be added to the ASA score.

Also, the ASA classification doesn't describe the general health status of the patient when excluding the condition that indicates the surgery. In fact, there are hospitals (e.g. Uppsala University Hospital) that do exclude the condition indicating the surgery. Thus, in such hospitals, ASA 1 may still refer to a patient in a severe medical emergency, such as for example a moribund patient due to a traumatic aortic rupture (which indicates the surgery) but otherwise being healthy.