Using Examples Best When Classifying ASA Physical Status

Despite being an important part of clinical practice for more than five decades, the American Society of Anesthesiologists (ASA) physical status classification system occasionally is criticized for its subjective nature, a trait that can lead to inconsistent assignments among health care professionals.

This problem can be ameliorated, a recent study has found, with the use of ASA-approved class-specific examples, which help anesthesia and nonanesthesia providers alike substantially increase their ability to determine the correct ASA class (Table 1).

Table 1. ASA Physical Status Classifications and Examples ASA PS Classification Definition Examples ASA I A normal healthy patient Healthy, nonsmoking, no or minimal alcohol use ASA II A patient with mild systemic disease Mild diseases only without substantive functional limitations. Examples include (but not limited to): current smoker, social alcohol drinker, pregnancy, obesity (30 < BMI < 40), well-controlled DM/HTN, mild lung disease ASA III A patient with severe systemic disease Substantive functional limitations; one or more moderate to severe diseases. Examples include (but not limited to): poorly controlled DM or HTN, COPD, morbid obesity (BMI ≥40), active hepatitis, alcohol dependence or abuse, implanted pacemaker, moderate reduction of ejection fraction, ESRD undergoing regularly scheduled dialysis, premature infant PCA <60 wk, history (>3 mo) of MI, CVA, TIA or CAD/stents ASA IV A patient with severe systemic disease that is a constant threat to life Examples include (but not limited to): recent (<3 mo) MI, CVA, TIA or CAD/stents; ongoing cardiac ischemia or severe valve dysfunction; severe reduction of ejection fraction; sepsis; DIC; ARD; or ESRD not undergoing regularly scheduled dialysis ASA V A moribund patient who is not expected to survive without the operation Examples include (but not limited to): ruptured abdominal/thoracic aneurysm, massive trauma, intracranial bleed with mass effect, ischemic bowel in the face of significant cardiac pathology or multiple organ/system dysfunction ASA VI A declared brain-dead patient whose organs are being removed for donor purposes   ARD, acid reflux disease; ASA, American Society of Anesthesiologists; BMI, body mass index; CAD, coronary artery disease; COPD, chronic obstructive pulmonary disease; CVA, cerebral vascular accident; DIC, disseminated intravascular coagulation; DM, diabetes mellitus, ESRD, end-stage renal disease; HTN, hypertension; MI, myocardial infarction; PCA, postconceptual age; PS, physical status; TIA, transient ischemic attack

“Part of the reason behind the 2014 development of the examples that accompany the ASA physical status classification system stems from the fact that the system is not used exclusively by professionals trained in anesthesia care,” stated Erin Hurwitz, MD, who was assistant professor of anesthesiology at The University of Texas Medical Branch at Galveston when the study was performed.

“So, if you are assigning a patient an ASA I or II physical status and undervaluing comorbidities that actually make them an ASA III, you may be putting patient safety at risk in certain situations.”

To help determine the utility of the examples in improving class assignment, Dr. Hurwitz and her colleagues recruited 779 anesthesia (from 41 states) and 110 nonanesthesia providers (from 18 states) into this Web-based study. As part of the questionnaire, participants were first asked to assign an ASA physical status level to 10 hypothetical cases using only the ASA definitions for reference.

“In the second part of the survey,” Dr. Hurwitz told Anesthesiology News, “they were given the same 10 cases in a different order. Except this time, they were also given a table that included the published examples and again asked to assign an ASA physical status classification.”

Anesthesia providers included physician anesthesiologists, anesthesiology residents and fellows, nurse anesthetists and anesthesiology assistants. “For nonanesthesia providers, we targeted areas in medicine that utilized the ASA physical status,” she said, “including gastroenterologists, pulmonary critical care physicians, interventional radiologists, oral-maxillofacial surgeons and nurses.”

ASA Class Examples Not Widely Known

As Dr. Hurwitz reported at the 2015 annual meeting of the American Society of Anesthesiologists (abstract A1278), clinicians of all stripes saw significant improvement in their ability to correctly identify a patient’s ASA physical status class when they used the examples (Table 2).

Table 2. Accuracy of ASA Physical Status Designations Provider Number Definition Only (No. Correct/10 Cases) Examples and Definitions (No. Correct/10 Cases) All anesthesia providers 779 5.8±1.6 7.7±1.7 All nonanesthesia providers 110 5.4±1.7 7.9±1.7 Anesthesiologists 524 5.9±1.6 7.7±1.7 Residents/fellows 90 5.8±1.8 7.7±1.8 Nurse anesthetists 125 5.4±1.6 7.5±1.8 Anesthesiologist assistants 37 5.4±1.2 7.5±1.9 Nonanesthesiologist physicians 69 5.7±1.5 7.9±1.8 Nurses 35 4.9±1.9 8.0±1.3

“When only the definitions were used, in only about half the cases did clinicians give the correct ASA physical status assignment,” Dr. Hurwitz explained. “But when the examples were added, the mean correct score went up to almost eight out of 10 cases.” Of note, only three of the 10 cases were correctly assigned at least 65% of the time when definitions alone were used. This climbed to nine of 10 when the examples were added (Figure).

Figure. Correct ASA physical status assignments with and without use of examples.

This kind of improvement should help level the playing field between health care providers who often interpret the same clinical situations very differently. “One of the criticisms of the ASA physical status system is that it’s somewhat subjective in nature,” Dr. Hurwitz told Anesthesiology News. “What constitutes a severe systemic disease to one provider may be something very different to another. So, this is a way to see if adding some objectivity can help improve consistency—and I think it does.”

Given these results, Dr. Hurwitz thought it important that clinicians familiarize themselves with the examples. “In talking to anesthesiologists, I have found that there are many people who are unaware that the published examples currently exist,” she explained. The examples are available on the ASA’s website atwww.asahq.org/​resources/​clinical-information/​asa-physical-status-classification-system.

Robert E. Johnstone, MD, professor of anesthesiology at West Virginia University in Morgantown, noted that the investigation confirms that adding examples improves the consistency of judging patient physical status. “A weakness of the study is that no final authority exists to determine physical status [PS], so comparisons with a ‘correct’ value are suspect, especially in gray areas,” said Dr. Johnstone. “Is a healthy person who trips while jogging and breaks some ribs a PS I [healthy], II [minor injury] or III [functionally impaired – cannot take a deep breath]? Any could be correct.” Some anesthesiologists, he added, think the magnitude or risk of the surgery plus the patient’s age also should factor into the physical status.

“The more consistency in physical status assignments the better, because work assignments, quality assessments and finances are affected,” Dr. Johnstone added. “Some clinicians work in ambulatory surgical units where only patients with PS I, II or III are allowed. Quality assessments are adjusted for physical status. Finally, some insurers pay extra for anesthetics involving higher physical status patients.”