Surgical Screening Tool Uncovers Hidden Sleep Apnea

A quick, cheap, and highly accurate scoring system can identify surgical patients who may have the potentially life-threatening condition of obstructive sleep apnea (OSA).

Researchers at the University of Toronto (Canada) developed the STOP questionnaire, a self-administered screening tool consisting of four simple questions answerable with a yes or no. The questionnaire was given to 2467 patients, 27.5% classified as being at high risk of OSA. For validation, the score from the STOP questionnaire was evaluated versus the apnea-hypopnea index from monitored polysomnography; in all 211 patients underwent polysomnography, 34 for the pilot test and 177 for validation.

The test consists of four questions:

S: Do you snore loudly?
T: Do you often feel tired, fatigued, or sleepy during daytime?
O: Has anyone observed you stop breathing during sleep?
P: Do you have or are you being treated for high blood pressure?

If a patient answers yes to two or more of these questions, then he or she is ranked as being at high risk for OSA. The study results showed that in the validation group, the apnea-hypopnea index was 20 +/- 6. The sensitivities of the STOP questionnaire with apnea-hypopnea index greater than 5, greater than 15, and greater than 30 set as cutoff points were 65.6, 74.3, and 79.5%, respectively. When incorporating body mass index (BMI), age over 50, neck circumference, and male gender (all known risk factors for OSA) into the STOP questionnaire, sensitivities were increased to 83.6, 92.9, and 100% with the same apnea-hypopnea index cutoffs. In a companion study to the STOP questionnaire study, the researchers also validated two other screening tools that have been used previously but not definitively validated for surgical patients: the 11-question Berlin Questionnaire and the American Society of Anesthesiologists (ASA) checklist, which contains 12 checkable items for adults and 14 for children. According to the researchers, the validation of these three studies offers objective, reliable tools for detecting OSA in surgical patients. Both studies were published in the May 2008 issue of Anesthesiology.

"Identifying patients with OSA is the first step in preventing postoperative complications,” said lead author Francis Chung, M.D. "Untreated OSA patients are known to have a higher incidence of difficult intubation, postoperative complications, increased intensive care admissions, and greater duration of hospital stay.”


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