Questionnaire Accurately Spots Surgical, Clinic Apnea Patients

OA study has confirmed that in both sleep clinic patients and surgical patients, the higher the score on the STOP-Bang questionnaire, the greater the probability that patients will suffer from moderate-to-severe or severe obstructive sleep apnea (OSA).

Frances Chung, MBBS, professor of anesthesiology at the University Health Network, University of Toronto, Ontario, and the developer of the questionnaire (Figure), previously validated the instrument for surgical patients in 2008. She and her team strengthened that validation with a new meta-analysis.

Snoring?
Tired?
Observed stop breathing, or choking/gasping?
Pressure (high blood pressure)?
Body mass index >35 kg/m²?
Age >50 years?
Neck size large?
Gender, male?

Figure. Components of the STOP-Bang questionnaire. High OSA risk is a yes to 5 to 8 of the questions.

“Patients in the clinical setting may want to know their chances of having OSA based on their STOP-Bang score, so that’s what we were looking for here,” said Mahesh Nagappa, MD, a clinical fellow at Toronto Western Hospital, in Ontario, Canada. Diagnosing patients who may develop OSA is important given its increased risk for complications; polysomnography is accurate, but time-consuming and costly.

To help confirm the efficacy of the STOP-Bang questionnaire in predicting moderate to severe and severe OSA, the investigators searched the literature for relevant English-language studies for 2008 to 2014. There were 340 citations, of which five prospective studies were deemed relevant for analysis. Studies were included if 1) the STOP-Bang questionnaire was used as a screening tool for moderate to severe and severe OSA in adults, 2) the accuracy of the STOP-Bang questionnaire was validated by polysomnography, 3) data were available on the apnea-hypopnea index (≥15) or respiratory disturbance index and 4) participants were likely to suffer moderate to severe and severe OSA.

A total of 2,792 patients were included in the analysis, comprising three studies in sleep clinic patients (n=1,835) and two in surgical patients (n=957). The researchers found that in sleep clinic patients, the probability of moderate to severe OSA was 52% with a STOP-Bang score of 3. This risk increased incrementally with STOP-Bang scores of 4 (62%), 5 (72%), 6 (82%) and 7/8 (92%). The same pattern existed for severe OSA, with STOP-Bang scores of 4, 5, 6 and 7/8 corresponding to OSA incidence of 35%, 45%, 55% and 75%, respectively.

“The same pattern existed for the surgical population as well,” Dr. Nagappa said at the 2015 annual meeting of the Canadian Anesthesiologists’ Society (abstract 82753). Indeed, the probability of moderate to severe OSA in surgical patients with a STOP-Bang score of 3 was 40%. This rose incrementally with increasing STOP-Bang scores of 4 (48%), 5 (60%), 6 (68%) and 7/8 (80%). A similar relationship was found for severe OSA, with STOP-Bang scores of 4, 5, 6 and 7/8 corresponding to OSA rates of 25%, 35%, 45% and 65%, respectively.

“What are the clinical implications of this?” Dr. Nagappa asked. “It helps us to categorize patients according to STOP-Bang score. For example, if a patient has a score of 0 to 2, they’ll have very little chance of suffering moderate to severe OSA. On the other extreme, if the STOP-Bang scores are very high—such as more than 5—the chances of having OSA are much greater.”

Such categorizations will help streamline the diagnosis and treatment of OSA, allowing for more efficient use of resources. “When the STOP-Bang score is high, we can tell the patient that the chances of having OSA are also high, and the anesthesiologist can plan perioperative management, as per OSA guidelines,” he added. “Perioperative management will comprise short-acting, rapid-recovery agents with minimal respiratory depression. Postoperative monitoring is essential. We can always confirm OSA findings by polysomnography after surgery. Elective surgery patients we suspect to be suffering from severe OSA will be sent to polysomnography and sleep consult for CPAP [continuous positive airway pressure therapy].”

The strong correlation between STOP-Bang score and OSA has brought about changes in the way clinicians use polysomnography. “If we use STOP-Bang alone, we might miss a few patients,” Dr. Nagappa said. “We may also have a few false-positives. So STOP-Bang should not replace polysomnography. But in the perioperative setting, we can mitigate the need for polysomnography by using STOP-Bang.”