Obstructive Sleep Apnea and Perioperative Outcomes: We Should Not Confuse the Probability With the Established Diagnosis.

Abstract

To the Editor We read with interest the recently published work by Szeto et al.1 The authors assessed the outcomes and safety among patients with obstructive sleep apnea (OSA) undergoing surgical procedures in an ambulatory facility. We commend the authors for addressing important questions regarding the care of OSA patients in the ambulatory setting. However, we have some methodological concerns. The authors have categorized their patients into low, moderate, or high risk according to the Snoring, Tired, Observed apnea, high blood Pressure, BMI >35 kg m-2, Age over 50 years, Neck circumference >40 cm, male Gender (STOP-Bang) score. The reference standard for the diagnosis of OSA uses polysomnography measures, including the Apnea-Hypopnea Index (AHI). However, obtaining a recent polysomnography in all patients undergoing ambulatory surgery is a challenge. Hence, several screening scores have been proposed to assess the risk of OSA, STOP-Bang being probably the most frequently used. In a recent study comparing 4 screening scores (STOP-Bang, perioperative sleep apnea prediction [P-SAP], OSA 50, and DES-OSA), in a European surgical population, we found that a STOP-Bang ≥5 has a sensitivity of 81% and a specificity of 47% for the detection of OSA patients.2 Thus, 19% of the patients with a severe OSA have a STOP-Bang score <5, and 53% of the patients with a STOP-Bang score ≥5 did not suffer from severe OSA. Hence, it must be kept in mind that exclusively using the STOP-Bang score to categorize patients regarding OSA can lead to misclassification. In addition, the authors excluded from their study patients with an American Society of Anesthesiologists (ASA) physical status of IV. This suggests that some patients with OSA, and probably the most severe, were excluded from the study by Szeto et al.1 Only severe OSA patients (AHI >30 events/h) appear to exhibit a higher risk of postoperative complications.3 Thus, excluding ASA IV patients may have contributed to an underestimation of risks associated with OSA patients. Nevertheless, patients with an ASA physical status IV are seldom eligible for ambulatory surgery. We think that the article by Szeto et al1 would have benefited from a title like “Outcomes and Safety Among Patients With Suspected Obstructive Sleep Apnea Undergoing Cancer Surgery Procedures in a Freestanding Ambulatory Surgical Facility.” We agree that most patients with suspected OSA are eligible for ambulatory surgery. However, the aforementioned limitations should be kept in mind when developing and publishing guidelines on preoperative identification of patients with OSA and/or on preoperative management of such patients. Eric P. Deflandre, MD, PhD, FCCP, FAHADepartment of Anesthesia and ICMClinique Saint-Luc de BougeNamur, BelgiumDepartment of Ambulatory SurgeryClinique Saint-Luc de BougeNamur, BelgiumDepartment of Anesthesia and ICMUniversity of LiegeLiege, Belgium[email protected] Jean-Francois H. Brichant, MD, PhDDepartment of Anesthesia and ICMUniversity of LiegeLiege, Belgium