Patients with an ASA Physical Status of IV had an 89-fold higher odds of 30-day mortality following outpatient surgery compared to healthy patients.
Observational (n=2,089,830)
Yes
Does the ASA Physical Status Classification predict 30-day medical complications and mortality in patients undergoing outpatient surgery?
The ASA Physical Status Classification is a reliable, independent predictor of 30-day medical complications, readmissions, and mortality following ambulatory surgery, suggesting high-risk patients may be better suited for inpatient settings.
Odds Ratio: 89 (95% CI 55–143)
p-value: p=<0.001
BACKGROUND: Seventy percent of surgical procedures are currently performed in the outpatient setting. Although the American Society of Anesthesiologists (ASA) Physical Classification ability to predict risk has been evaluated for in-patient surgeries, an evaluation in outpatient surgeries has yet to be performed. The major goal of the current study is to determine if the ASA classification is an independent predictor for morbidity and mortality for outpatient surgeries. METHODS: The 2005 through 2016 NSQIP Participant Use Data Files were queried to extract all patients scheduled for outpatient surgery. ASA PS class was the primary independent variable of interest. The primary outcome was 30-day medical complications, defined as having one or more of the following postoperative outcomes: (1) deep vein thrombosis, (2) pulmonary embolism, (3) reintubation, (4) failure to wean from ventilator, (5) renal insufficiency, (6) renal failure, (7) stroke, (8) cardiac arrest, (9) myocardial infarction, (10) pneumonia, (11) urinary tract infection, (12) systemic sepsis or septic shock. Mortality was also evaluated as a separate outcome. RESULTS: A total of 2,089,830 cases were included in the study. 24,777 (1.19%) patients had medical complications and 1,701 (0.08%) died within 30 days. ASA PS IV patients had a much greater chance of dying when compared to healthy patients, OR (95%CI) of 89 (55 to 143), P < 0.001. Nonetheless, over 30,000 ASA PS IV patients had surgery in the outpatient setting. Multivariable analysis demonstrated a stepwise independent association between ASA PS class and medical complications (C statistic = 0.70), mortality (C statistic = 0.74) and readmissions (C statistic = 0.67). Risk stratifying ability was maintained across surgical procedures and anesthesia techniques. CONCLUSIONS: ASA PS class is a simple risk stratification tool for surgeries in the outpatient setting. Patients with higher ASA PS classes subsequently developed medical complications or mortality at a greater frequency than patients with lower ASA PS class after outpatient surgery. Our results suggest that the ambulatory setting may not be able to match the needs of high-risk patients.
Foley et al. (2021) conducted an observational in Outpatient surgery (n=2,089,830). ASA Physical Status IV vs. ASA Physical Status I (healthy patients) was evaluated on 30-day mortality (OR 89, 95% CI 55-143, p=<0.001). Patients with an ASA Physical Status of IV had an 89-fold higher odds of 30-day mortality following outpatient surgery compared to healthy patients.