STOP-Bang Questionnaire

A Practical Approach to Screen for Obstructive Sleep Apnea
      There exists a high prevalence of OSA in the general population, a great proportion of which remains undiagnosed. The snoring, tiredness, observed apnea, high BP, BMI, age, neck circumference, and male gender (STOP-Bang) questionnaire was specifically developed to meet the need for a reliable, concise, and easy-to-use screening tool. It consists of eight dichotomous (yes/no) items related to the clinical features of sleep apnea. The total score ranges from 0 to 8. Patients can be classified for OSA risk based on their respective scores. The sensitivity of STOP-Bang score ≥ 3 to detect moderate to severe OSA (apnea-hypopnea index [AHI] > 15) and severe OSA (AHI > 30) is 93% and 100%, respectively. Corresponding negative predictive values are 90% and 100%. As the STOP-Bang score increases from 0 to 2 up to 7 to 8, the probability of moderate to severe OSA increases from 18% to 60%, and the probability of severe OSA rises from 4% to 38%. Patients with a STOP-Bang score of 0 to 2 can be classified as low risk for moderate to severe OSA whereas those with a score of 5 to 8 can be classified as high risk for moderate to severe OSA. In patients whose STOP-Bang scores are in the midrange (3 or 4), further criteria are required for classification. For example, a STOP-Bang score of ≥ 2 plus a BMI > 35 kg/m2 would classify that patient as having a high risk for moderate to severe OSA. In this way, patients can be stratified for OSA risk according to their STOP-Bang scores.

      Key Words

      Abbreviations:

      AHI (apnea-hypopnea index), NPV (negative predictive value), PPV (positive predictive value), PSG (polysomnogram), STOP-Bang (snoring, tiredness, observed apnea, high BP, BMI, age, neck circumference, and male gender)
      OSA is the most common type of sleep-disordered breathing. In OSA, repetitive episodes of partial and complete pharyngeal collapse cause a reduction or total cessation of airflow during sleep. The condition is associated with hypertension, cerebrovascular disease, myocardial infarction, diabetes, long-term cognitive impairment, and increased all-cause mortality.
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      This chronic sleep disturbance results in daytime sleepiness and fatigue that impedes a patient’s ability to function, thereby negatively affecting his or her quality of life. The current prevalence rate of moderate to severe OSA (apnea-hypopnea index [AHI] ≥ 15 events/h) is about 10% to 20%.
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      This estimated prevalence rate represents a substantial increase over the past 2 decades.
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      Increased prevalence of sleep-disordered breathing in adults.
      Since these apnea and hypopnea events occur during sleep, most patients with OSA may not be aware that they have the condition. It has been estimated that up to 80% of individuals with moderate to severe OSA may remain undiagnosed and, more alarmingly, untreated.
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      Estimation of the clinically diagnosed proportion of sleep apnea syndrome in middle-aged men and women.
      The prevalence of OSA specifically found in surgical patients differs among various populations. The prevalence rate is approximately 70% in patients undergoing bariatric surgery
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      Obstructive sleep-related breathing disorders in patients evaluated for bariatric surgery.
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      The impact of sleep apnea on postoperative utilization of resources and adverse outcomes.
      and 7.2% among patients undergoing a variety of surgeries.
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      • et al.
      Derivation and validation of a simple perioperative sleep apnea prediction score.
      Since 60% of surgical patients with moderate to severe OSA were not recognized or diagnosed preoperatively,
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      the point estimates from these studies may actually be an underestimation.
      Because of the potentially serious adverse consequences associated with untreated OSA in the general and surgical population, prompt diagnosis and treatment of unrecognized OSA is critical. The reference standard for diagnosis of OSA is an overnight polysomnogram (PSG). However, the procedure is time-consuming, labor-intensive, and costly. Growing awareness of sleep apnea has extended the already long waiting lists in many sleep laboratories.
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      • Wheatley J.
      Access to diagnosis and treatment of patients with suspected sleep apnea.
      As a result, patients with OSA are currently left waiting a mean of 11.6 months before being able to initiate medical therapy (CPAP) and 16.2 months before being able to initiate surgical therapy in Ontario, Canada.
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      • Wong E.
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      Moreover, PSG requires the expertise of sleep medicine specialists, who may not be readily available at many hospitals and medical centers. All of these factors exacerbate delays that can prevent prompt diagnosis and treatment of OSA, which further emphasizes the vital need for a simple, practical, and reliable method of identifying and triaging patients at high risk of OSA. In an effort to deal with this issue, a number of screening tests were developed to identify high-risk patients.
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      Many are lengthy and complicated, and require upper airway assessment, which makes them inconvenient to use and vulnerable to variability among clinicians performing the upper airway assessment.

      The STOP and STOP-Bang Questionnaire

      The snoring, tiredness, observed apnea, high BP (STOP) and snoring, tiredness, observed apnea, high BP-BMI, age, neck circumference and gender (STOP-Bang) questionnaires (e-Appendix 1) were developed in response to the need for a concise, user-friendly OSA screening tool in preoperative clinics.
      • Chung F.
      • Yegneswaran B.
      • Liao P.
      • et al.
      STOP questionnaire: a tool to screen patients for obstructive sleep apnea.
      The STOP questionnaire includes four questions related to snoring, tiredness, observed apnea and high blood pressure, and shows a moderately high level of sensitivity (65.6%) and specificity (60%) in detecting OSA (AHI > 5) in surgical patients.
      • Chung F.
      • Yegneswaran B.
      • Liao P.
      • et al.
      STOP questionnaire: a tool to screen patients for obstructive sleep apnea.
      For moderate to severe OSA (AHI > 15), the sensitivity and specificity of the STOP questionnaire are 74% and 53%, respectively. For severe OSA (AHI > 30), sensitivity is 80% and specificity is 49%.
      • Chung F.
      • Yegneswaran B.
      • Liao P.
      • et al.
      STOP questionnaire: a tool to screen patients for obstructive sleep apnea.
      The STOP-Bang questionnaire includes the four questions used in the STOP questionnaire plus four additional demographic queries,
      • Chung F.
      • Yegneswaran B.
      • Liao P.
      • et al.
      STOP questionnaire: a tool to screen patients for obstructive sleep apnea.
      for a total of eight dichotomous (yes/no) questions related to the clinical features of sleep apnea (snoring, tiredness, observed apnea, high blood pressure, BMI, age, neck circumference and male gender). For each question, answering “yes” scores 1, a “no” response scores 0, and the total score ranges from 0 to 8. The components of STOP questionnaire were selected based on the factor analysis of 14 candidate questions designed to reflect snoring, daytime tiredness, observed breathing cessation, and high BP.
      • Chung F.
      • Yegneswaran B.
      • Liao P.
      • et al.
      STOP questionnaire: a tool to screen patients for obstructive sleep apnea.
      The “Bang” items were chosen based on univariate analysis of item predictive performance. The diagnostic OR to detect OSA (AHI > 5 events/h) was 1.949 (95% CI, 0.792-4.798) for BMI > 35 kg/m2; 4.024 (95% CI, 2.023-8.003) for age > 50 years; 4.943 (95% CI, 1.963-12.446) for neck circumference > 40 cm, and 2.767 (95% CI, 1.419-5.396) for male gender (F. C., unpublished data, February 2014).
      The questionnaire can be completed quickly and easily (usually within 1-2 min), and overall response rates are typically high (90%-100%).
      • Chung F.
      • Yegneswaran B.
      • Liao P.
      • et al.
      STOP questionnaire: a tool to screen patients for obstructive sleep apnea.
      The questionnaire has demonstrated a high sensitivity using a cutoff score of ≥ 3: 84% in detecting any sleep apnea (AHI > 5 events/h), 93% in detecting moderate to severe sleep apnea (AHI > 15 events/h), and 100% in detecting severe sleep apnea (AHI > 30 events/h).
      • Chung F.
      • Yegneswaran B.
      • Liao P.
      • et al.
      STOP questionnaire: a tool to screen patients for obstructive sleep apnea.
      Corresponding specificities were 56.4%, 43%, and 37%.
      • Chung F.
      • Yegneswaran B.
      • Liao P.
      • et al.
      STOP questionnaire: a tool to screen patients for obstructive sleep apnea.
      If patients score 0 to 2 on the STOP-Bang questionnaire, they are considered to be at low risk of OSA, and the possibility of those patients having moderate to severe sleep apnea can be confidently ruled out.
      Because of its ease of use, efficiency, and high sensitivity, the STOP-Bang questionnaire has been widely adopted and validated in various populations and among patients with assorted medical conditions. It has been applied in sleep
      • Farney R.J.
      • Walker B.S.
      • Farney R.M.
      • Snow G.L.
      • Walker J.M.
      The STOP-Bang equivalent model and prediction of severity of obstructive sleep apnea: relation to polysomnographic measurements of the apnea/hypopnea index.

      Boynton G, Vahabzadeh A, Hammoud S, Ruzicka DL, Chervin RD. Validation of the STOP-BANG questionnaire among patients referred for suspected obstructive sleep apnea [published online ahead of print September 23, 2013]. J Sleep Disord Treat Care. http://dx.doi.org/10.4172/2325-9639.1000121.

      • Luo J.
      • Huang R.
      • Zhong X.
      • Xiao Y.
      • Zhou J.
      Value of STOP-Bang questionnaire in screening patients with obstructive sleep apnea hypopnea syndrome in sleep disordered breathing clinic.
      • Ong T.H.
      • Raudha S.
      • Fook-Chong S.
      • Lew N.
      • Hsu A.A.
      Simplifying STOP-BANG: use of a simple questionnaire to screen for OSA in an Asian population.
      • El-Sayed I.H.
      Comparison of four sleep questionnaires for screening obstructive sleep apnea.
      • Yu Y.
      • Mei W.
      • Cui Y.
      [Primary evaluation of the simplified Chinese version of STOP-Bang scoring model in predicting obstructive sleep apnea hypopnea syndrome].
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      • Driver H.S.
      • Stewart S.C.
      • Fitzpatrick M.F.
      Comparing a combination of validated questionnaires and level III portable monitor with polysomnography to diagnose and exclude sleep apnea.
      • Vana K.D.
      • Silva G.E.
      • Goldberg R.
      Predictive abilities of the STOP-Bang and Epworth Sleepiness Scale in identifying sleep clinic patients at high risk for obstructive sleep apnea.
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      • Macfarlane D.
      • et al.
      Predicting sleep disordered breathing in outpatients with suspected OSA.
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      • van Hasselt C.A.
      Evaluation and validation of four translated Chinese questionnaires for obstructive sleep apnea patients in Hong Kong.
      and medical clinics,
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      Screening for obstructive sleep apnea among individuals with severe mental illness at a primary care clinic.
      surgical patients,
      • Guralnick A.S.
      • Pant M.
      • Minhaj M.
      • Sweitzer B.J.
      • Mokhlesi B.
      CPAP adherence in patients with newly diagnosed obstructive sleep apnea prior to elective surgery.
      • Chung F.
      • Subramanyam R.
      • Liao P.
      • Sasaki E.
      • Shapiro C.
      • Sun Y.
      High STOP-Bang score indicates a high probability of obstructive sleep apnoea.
      the general population,
      • Cruces-artero C.
      • Martin-miguel M.
      • Hervesbeloso C.
      • et al.
      Validation of the STOP and STOP BANG questionnaire in primary health care [abstract].
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      • Sherrill D.L.
      • Quan S.F.
      Identification of patients with sleep disordered breathing: comparing the four-variable screening tool, STOP, STOP-Bang, and Epworth Sleepiness Scales.
      pregnant patients,
      • Goldfarb I.T.
      • Sparks T.N.
      • Ortiz V.E.
      • Kaimal A.
      Association between a positive screen on the STOP-BANG obstructive sleep apnea tool and preeclampsia [abstract].
      individuals with mental illness,
      • Annamalai A.
      • Palmese L.B.
      • Chwastiak L.A.
      • Srihari V.H.
      • Tek C.
      High rates of obstructive sleep apnea symptoms among patients with schizophrenia.
      highway bus drivers,
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      • Demir A.
      • Ardic S.
      Comparison of four established questionnaires to identify highway bus drivers at risk for obstructive sleep apnea in Turkey.
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      Excessive daytime sleepiness among Turkish public transportation drivers: A risk for road traffic accidents?.
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      • Dania M.G.
      High-risk of obstructive sleep apnea and excessive daytime sleepiness among commercial intra-city drivers in Lagos metropolis.
      and patients with renal failure.
      • Nicholl D.D.
      • Ahmed S.B.
      • Loewen A.H.
      • et al.
      Diagnostic value of screening instruments for identifying obstructive sleep apnea in kidney failure.

      Association Between STOP-Bang Scores and Predictive Probability of OSA

      Although the high sensitivity of the STOP-Bang questionnaire makes it useful as an OSA screening tool, it is possible that the modest specificity (43% to detect moderate to severe sleep apnea) will yield a high false-positive rate.
      • Chung F.
      • Yegneswaran B.
      • Liao P.
      • et al.
      STOP questionnaire: a tool to screen patients for obstructive sleep apnea.
      This, in turn, could result in unnecessary referral to sleep clinics for polysomnography, as well as increase the cost of care for surgical patients owing to additional perioperative monitoring. To address these issues effectively and help curb unnecessary treatment or expenses, we further investigated the relationship between STOP-Bang scores and the predicted probability of OSA specifically in surgical patients.
      • Chung F.
      • Subramanyam R.
      • Liao P.
      • Sasaki E.
      • Shapiro C.
      • Sun Y.
      High STOP-Bang score indicates a high probability of obstructive sleep apnoea.
      We discovered that as the STOP-Bang scores increased from 0 to 2 up to 7 to 8, the probability of moderate to severe OSA increased from 18% to 60% and the probability of severe OSA rose from 4% to 38% (Table 1).
      • Chung F.
      • Subramanyam R.
      • Liao P.
      • Sasaki E.
      • Shapiro C.
      • Sun Y.
      High STOP-Bang score indicates a high probability of obstructive sleep apnoea.
      Table 1STOP-Bang Scores and Predicted Probabilities for Any OSA, Moderate-to-Severe OSA, and Severe OSA in a Surgical Population
      (Adapted with permission Chung et al.
      • Chung F.
      • Subramanyam R.
      • Liao P.
      • Sasaki E.
      • Shapiro C.
      • Sun Y.
      High STOP-Bang score indicates a high probability of obstructive sleep apnoea.
      )
      STOP-Bang ScoreAny OSA (AHI > 5)Moderate/Severe OSA (AHI > 15)Severe OSA (AHI > 30)
      0-20.46 (0.39-0.53)0.18 (0.13-0.24)0.04 (0.02-0.08)
      30.72 (0.65-0.78)0.36 (0.29-0.43)0.13 (0.09-0.19)
      40.73 (0.66-0.79)0.42 (0.34-0.49)0.18 (0.13-0.25)
      50.77 (0.69-0.84)0.50 (0.42-0.59)0.30 (0.23-0.39)
      60.79 (0.68-0.87)0.57 (0.45-0.69)0.32 (0.22-0.44)
      7 and 80.86 (0.72-0.93)0.60 (0.44-0.73)0.38 (0.29-0.53)
      Data are given as probability (95% CI).
      AHI = apnea-hypopnea index; STOP-Bang = snoring, tiredness, observed apnea, high BP, BMI, age, neck circumference, and male gender.
      In total, the relationship between the various STOP-Bang scores and the predicted probability of OSA has been investigated through four studies: two conducted with patients referred to sleep clinics
      • Farney R.J.
      • Walker B.S.
      • Farney R.M.
      • Snow G.L.
      • Walker J.M.
      The STOP-Bang equivalent model and prediction of severity of obstructive sleep apnea: relation to polysomnographic measurements of the apnea/hypopnea index.
      • Luo J.
      • Huang R.
      • Zhong X.
      • Xiao Y.
      • Zhou J.
      STOP-Bang questionnaire is superior to Epworth sleepiness scales, Berlin questionnaire, and STOP questionnaire in screening obstructive sleep apnea hypopnea syndrome patients.
      and two with surgical patients.
      • Guralnick A.S.
      • Pant M.
      • Minhaj M.
      • Sweitzer B.J.
      • Mokhlesi B.
      CPAP adherence in patients with newly diagnosed obstructive sleep apnea prior to elective surgery.
      • Chung F.
      • Subramanyam R.
      • Liao P.
      • Sasaki E.
      • Shapiro C.
      • Sun Y.
      High STOP-Bang score indicates a high probability of obstructive sleep apnoea.
      Figure 1 features the results of pooled data from these studies. In both sleep clinic (Fig 1A, 1B) (N = 1,852) and surgical patients (Fig 1C, 1D) (N = 957), the probability of moderate OSA (AHI, 15-30) (Fig 1A, 1C) stayed almost the same in patients with STOP-Bang scores of 3, 4, and 5, and then gradually decreased at STOP-Bang scores of 6 and 7/8. In contrast, the probability of severe OSA (AHI > 30) (Fig 1B, 1D) steadily increased as the STOP-Bang score increased from 3 to 7 or 8. The data indicate that as the STOP-Bang score increases, the probability of severe OSA increases but the probability of moderate OSA does not.
      Figure thumbnail gr1
      Figure 1Relationship between SBQ score and the probability of OSA. A, SBQ score and probability of moderate OSA (apnea-hypopnea index [AHI] > 15-30) in sleep clinic patients. B, SBQ score and probability of severe OSA (AHI > 30) in sleep clinic patients. C, SBQ score and probability of moderate OSA (AHI > 15-30) in surgical patients. D, SBQ score and probability of severe OSA (AHI > 30) in surgical patients. (A) and (B) are based on the meta-analysis of two studies in sleep clinics.
      • Farney R.J.
      • Walker B.S.
      • Farney R.M.
      • Snow G.L.
      • Walker J.M.
      The STOP-Bang equivalent model and prediction of severity of obstructive sleep apnea: relation to polysomnographic measurements of the apnea/hypopnea index.
      • Chung F.
      • Yang Y.
      • Brown R.
      • Liao P.
      Alternative scoring models of STOP-Bang questionnaire improve specificity to detect undiagnosed obstructive sleep apnea.
      (C) and (D) are based on the meta-analysis of two studies in surgical patients.
      • Guralnick A.S.
      • Pant M.
      • Minhaj M.
      • Sweitzer B.J.
      • Mokhlesi B.
      CPAP adherence in patients with newly diagnosed obstructive sleep apnea prior to elective surgery.
      • Chung F.
      • Subramanyam R.
      • Liao P.
      • Sasaki E.
      • Shapiro C.
      • Sun Y.
      High STOP-Bang score indicates a high probability of obstructive sleep apnoea.
      SBQ = STOP-Bang questionnaire; STOP-Bang = snoring, tiredness, observed apnea, high BP, BMI, age, neck circumference, and male gender.

      Alternative Models for Scoring the STOP-Bang Questionnaire

      For ease of use, all items on the STOP-Bang questionnaire are treated equally for scoring purposes, using a count of 0 or 1. The items on the questionnaire do not share an equal predictive weight for OSA.
      • Ramachandran S.K.
      • Josephs L.A.
      A meta-analysis of clinical screening tests for obstructive sleep apnea.
      • Chung F.
      • Yegneswaran B.
      • Liao P.
      • et al.
      STOP questionnaire: a tool to screen patients for obstructive sleep apnea.
      In the “Bang” components, BMI > 35 kg/m2, neck circumference > 40 cm, and male gender are more predictive than being of aged > 50 years.
      • Chung F.
      • Yang Y.
      • Brown R.
      • Liao P.
      Alternative scoring models of STOP-Bang questionnaire improve specificity to detect undiagnosed obstructive sleep apnea.
      Whereas previous studies showed that the prevalence of sleep apnea tends to increase with age, the severity of sleep apnea—as indicated by both the number of events and the minimum oxygen saturation—actually decreases with age.
      • Bixler E.O.
      • Vgontzas A.N.
      • Ten H.T.
      • Tyson K.
      • Kales A.
      Effects of age on sleep apnea in men: I. Prevalence and severity.
      The predictive performance of specific combinations of items has also been explored.
      • Chung F.
      • Yang Y.
      • Brown R.
      • Liao P.
      Alternative scoring models of STOP-Bang questionnaire improve specificity to detect undiagnosed obstructive sleep apnea.
      Compared with the specificity of 31% for detecting moderate to severe OSA using a combination of any three positive items on the STOP-Bang questionnaire, the following three combinations significantly improve the specificity to detect any OSA (AHI > 5), moderate to severe OSA (AHI > 15), and severe OSA (AHI > 30) at the expense of sensitivity: (1) STOP score ≥ 2 plus BMI > 35 kg/m2; (2) STOP score ≥ 2 plus neck circumference > 40 cm (16 in); and (3) STOP score ≥ 2 plus male gender.
      • Chung F.
      • Yang Y.
      • Brown R.
      • Liao P.
      Alternative scoring models of STOP-Bang questionnaire improve specificity to detect undiagnosed obstructive sleep apnea.
      The specificity to detect moderate to severe OSA increases as follows based on those different combinations: to 85% for the combination of a STOP score ≥ 2 plus BMI > 35 kg/m2; to 79% for the combination of a STOP score ≥ 2 plus neck circumference > 40 cm (16 in); and to 77% for the combination of a STOP score ≥ 2 plus male. These valuable data can assist in accurately identifying more patients with moderate to severe OSA (Table 2).
      Table 2Predictive Performance of Combination of Two Items From STOP and One From Bang for Identifying Patients With Moderate to Severe Obstructive Sleep Apnea (Apnea-Hypopnea Index > 15)
      (Adapted with permission Chung et al.
      • Chung F.
      • Yang Y.
      • Brown R.
      • Liao P.
      Alternative scoring models of STOP-Bang questionnaire improve specificity to detect undiagnosed obstructive sleep apnea.
      )
      CutoffSensitivitySpecificityPPVNPV
      STOP-Bang ≥ 387.3 (81.8-91.6)30.7 (25.7-36.1)43.8 (38.8-48.8)79.7 (71.5-86.4)
      STOP ≥ 2 + Bang ≥ 171.6 (64.7-77.8)46.1 (40.5-51.7)45.0 (39.5-50.7)72.4 (65.7-78.4)
      STOP ≥ 2 + BMI > 35 kg/m220.8 (15.4-27.2)85.0 (80.6-88.7)46.1 (35.4-57.0)63.5 (58.7-68.0)
      STOP ≥ 2 + Neck > 40 cm33.5 (27.0-40.6)79.0 (74.1-83.3)49.6 (40.8-58.4)65.8 (60.8-70.5)
      STOP ≥ 2 + male gender40.1 (33.2-47.3)76.8 (71.8-81.3)51.6 (43.4-59.8)67.5 (62.4-72.3)
      STOP ≥ 2 + age > 50 y59.4 (52.2-66.3)56.1 (50.5-61.6)45.5 (39.3-51.8)69.1 (63.1-74.7)
      Data are presented as average (95% CI).
      Bang = BMI, age, neck circumference, and male gender; NPV = negative predictive value; PPV = positive predictive value; STOP = snoring, tiredness, observed apnea, and high BP.

      The STOP-Bang Questionnaire and Serum Bicarbonate

      Chronic daytime hypercapnia (PaCO2 ≥ 45 mm Hg) is found in 10% to 38% of patients with OSA,
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      Obesity hypoventilation syndrome: a state-of-the-art review.
      and as the severity of OSA increases, the risk of chronic daytime hypercapnia may also increase.
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      • Aboussouan L.
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      Determinants of hypercapnia in obese patients with obstructive sleep apnea: a systematic review and metaanalysis of cohort studies.
      Serum bicarbonate (HCO3-) may increase in moderate to severe OSA without meeting criteria of overt chronic daytime hypercapnia, as documented in obesity hypoventilation syndrome.
      • Kaw R.
      • Hernandez A.V.
      • Walker E.
      • Aboussouan L.
      • Mokhlesi B.
      Determinants of hypercapnia in obese patients with obstructive sleep apnea: a systematic review and metaanalysis of cohort studies.
      Obesity hypoventilation syndrome is defined by daytime hypercapnia and hypoxemia (PaCO2 > 45 mm Hg and PaO2 < 70 mm Hg) in an obese patient (BMI > 30 kg/m2) who has sleep-disordered breathing and which occurs in the absence of any other cause of hypoventilation.
      • Mokhlesi B.
      Obesity hypoventilation syndrome: a state-of-the-art review.
      Since nocturnal intermittent hypercapnia resulting from to obstructive apnea or hypopnea may lead to renal HCO3 retention to compensate for acute respiratory acidosis,
      • Norman R.G.
      • Goldring R.M.
      • Clain J.M.
      • et al.
      Transition from acute to chronic hypercapnia in patients with periodic breathing: predictions from a computer model.
      it may subsequently result in elevated serum HCO3. Our findings indicate that serum HCO3 is significantly correlated to AHI,
      • Chung F.
      • Chau E.
      • Yang Y.
      • Liao P.
      • Hall R.
      • Mokhlesi B.
      Serum bicarbonate level improves specificity of STOP-Bang screening for obstructive sleep apnea.
      and the addition of serum HCO3 ≥ 28 mmol/L to a STOP-Bang score ≥ 3 improves the specificity to predict moderate to severe OSA but decreases its sensitivity.
      • Chung F.
      • Chau E.
      • Yang Y.
      • Liao P.
      • Hall R.
      • Mokhlesi B.
      Serum bicarbonate level improves specificity of STOP-Bang screening for obstructive sleep apnea.
      Under that condition (a STOP-Bang score of ≥ 3 plus HCO3 ≥ 28 mmol/L), the specificity for detecting moderate to severe OSA increases from 30% to 82%, and from 28% to 80% for detecting severe OSA.
      • Chung F.
      • Chau E.
      • Yang Y.
      • Liao P.
      • Hall R.
      • Mokhlesi B.
      Serum bicarbonate level improves specificity of STOP-Bang screening for obstructive sleep apnea.

      Two-Step Strategy for Using STOP-Bang Questionnaire

      Based on these data,
      • Chung F.
      • Subramanyam R.
      • Liao P.
      • Sasaki E.
      • Shapiro C.
      • Sun Y.
      High STOP-Bang score indicates a high probability of obstructive sleep apnoea.
      • Chung F.
      • Yang Y.
      • Brown R.
      • Liao P.
      Alternative scoring models of STOP-Bang questionnaire improve specificity to detect undiagnosed obstructive sleep apnea.
      • Chung F.
      • Chau E.
      • Yang Y.
      • Liao P.
      • Hall R.
      • Mokhlesi B.
      Serum bicarbonate level improves specificity of STOP-Bang screening for obstructive sleep apnea.
      we propose a two-step algorithm (Fig 2 ) to use the STOP-Bang questionnaire to identify patients effectively with a high probability of moderate to severe sleep apnea. As shown in Figure 2, the first step is to check the STOP-Bang score. If a patient scores 0 to 2 on the STOP-Bang questionnaire, he or she is unlikely to have moderate to severe OSA. Conversely, a patient with a STOP-Bang score of 5 to 8 has a high probability of having moderate to severe OSA (Table 1).
      • Chung F.
      • Subramanyam R.
      • Liao P.
      • Sasaki E.
      • Shapiro C.
      • Sun Y.
      High STOP-Bang score indicates a high probability of obstructive sleep apnoea.
      The second step is for patients falling in the middle: those with STOP-Bang scores of 3 or 4. These patients can be further classified as having a higher risk for moderate to severe OSA if one of the following conditions is met: (1) the combination of a STOP score of ≥ 2 plus BMI > 35 kg/m2; (2) a STOP score of ≥ 2 plus male gender; (3) a STOP score of ≥ 2 plus neck circumference > 40 cm (16 in); or (4) a STOP-Bang score of ≥ 3 plus serum HCO3 ≥ 28 mmol/L. This two-step algorithm needs to be further validated prospectively.
      Figure thumbnail gr2
      Figure 2STOP-Bang algorithm with a two-step scoring strategy. See legend for expansion of abbreviation.

      STOP-Bang Questionnaire in the General Population and in Bus Drivers

      Studies in primary care patients demonstrate that the STOP-Bang questionnaire has predictive performance similar to that seen in surgical and sleep clinic patients.
      • Cruces-artero C.
      • Martin-miguel M.
      • Hervesbeloso C.
      • et al.
      Validation of the STOP and STOP BANG questionnaire in primary health care [abstract].
      • Silva G.E.
      • Vana K.D.
      • Goodwin J.L.
      • Sherrill D.L.
      • Quan S.F.
      Identification of patients with sleep disordered breathing: comparing the four-variable screening tool, STOP, STOP-Bang, and Epworth Sleepiness Scales.
      Silva et al
      • Silva G.E.
      • Vana K.D.
      • Goodwin J.L.
      • Sherrill D.L.
      • Quan S.F.
      Identification of patients with sleep disordered breathing: comparing the four-variable screening tool, STOP, STOP-Bang, and Epworth Sleepiness Scales.
      evaluated the STOP-Bang questionnaire in 4,770 participants in the Sleep Heart Health Study. The prevalence of moderate to severe OSA (respiratory disturbance index [RDI] ≥ 15 events/h) and severe OSA (RDI ≥ 30 events/h) in this population was 13% and 7%, respectively. The sensitivity of a STOP-Bang score ≥ 3 was 89% to detect moderate to severe OSA (RDI ≥ 15 events/h) and 93% to detect severe OSA (RDI ≥ 30 events/h). Specificities were 30% and 29%, respectively. Positive predictive values (PPV) were lower: 16% and 9%, respectively. Negative predictive values (NPV) were higher: 95% and 98%, respectively.
      • Silva G.E.
      • Vana K.D.
      • Goodwin J.L.
      • Sherrill D.L.
      • Quan S.F.
      Identification of patients with sleep disordered breathing: comparing the four-variable screening tool, STOP, STOP-Bang, and Epworth Sleepiness Scales.
      The relatively low PPV and high NPV were probably related to the relatively low OSA prevalence in the study population. In another study of 178 patients with 60% with OSA (AHI ≥ 5 events/h), the sensitivity of the STOP-Bang questionnaire to detect OSA (AHI ≥ 5 events/h) was 96% whereas the specificity was 24%, PPV was 66%, and NPV was 81%.
      • Cruces-artero C.
      • Martin-miguel M.
      • Hervesbeloso C.
      • et al.
      Validation of the STOP and STOP BANG questionnaire in primary health care [abstract].
      Further research is needed to investigate the association between STOP-Bang scores and OSA probability in the general population.
      The STOP-Bang questionnaire has also been evaluated for its ability to detect moderate to severe OSA in highway bus drivers.
      • Firat H.
      • Yuceege M.
      • Demir A.
      • Ardic S.
      Comparison of four established questionnaires to identify highway bus drivers at risk for obstructive sleep apnea in Turkey.
      The prevalence of moderate to severe OSA among the highway bus drivers was 54%. Compared with other questionnaires (Berlin, STOP, and OSA50), the STOP-Bang questionnaire had the highest sensitivity and NPV and was more helpful as a screening test to identify drivers at risk for OSA.
      • Firat H.
      • Yuceege M.
      • Demir A.
      • Ardic S.
      Comparison of four established questionnaires to identify highway bus drivers at risk for obstructive sleep apnea in Turkey.
      The sensitivity and specificity of a STOP-Bang score ≥ 3 to detect moderate to severe OSA were 87% and 49%, respectively. The PPV and NPV was 66% and 76%, respectively.
      • Firat H.
      • Yuceege M.
      • Demir A.
      • Ardic S.
      Comparison of four established questionnaires to identify highway bus drivers at risk for obstructive sleep apnea in Turkey.

      STOP-Bang Questionnaire in Obese Patients

      The prevalence of OSA is high in the obese population. In morbidly obese surgical patients (BMI ≥ 35 kg/m2), 84% had OSA (AHI > 5 events/h), 47% had moderate to severe OSA (AHI > 15 events/h), and 27% had severe OSA (AHI > 30 events/h).
      • Chung F.
      • Yang Y.
      • Liao P.
      Predictive performance of the STOP-Bang score for identifying obstructive sleep apnea in obese patients.
      We evaluated the predictive performance of the STOP-Bang questionnaire for OSA in obese (BMI ≥ 30 kg/m2) and morbidly obese (BMI ≥ 35 kg/m2) surgical patients.
      • Chung F.
      • Yang Y.
      • Liao P.
      Predictive performance of the STOP-Bang score for identifying obstructive sleep apnea in obese patients.
      Although STOP-Bang ≥ 3 is very sensitive (sensitivity range, 91%-100%) to detect OSA in obese and morbidly obese patients, the specificity is low (from 7%-28%), yielding high false-positive rates. A STOP-Bang score cutoff of 4 provides a better balance of sensitivity and specificity in the obese population. In morbidly obese patients, a STOP-Bang score ≥ 4 retained high sensitivity across the entire spectrum of OSA severity, with a sensitivity of 90% for detecting severe OSA,
      • Chung F.
      • Yang Y.
      • Liao P.
      Predictive performance of the STOP-Bang score for identifying obstructive sleep apnea in obese patients.
      whereas a STOP-Bang score ≥ 6 demonstrated a specificity of 81% for detecting severe OSA.
      • Chung F.
      • Yang Y.
      • Liao P.
      Predictive performance of the STOP-Bang score for identifying obstructive sleep apnea in obese patients.

      OSA Screening: Benefits and Challenges

      The high prevalence of undiagnosed OSA requires a reliable, efficient, and easily used screening tool. The STOP-Bang questionnaire has been widely adopted to fulfill this need. As the STOP-Bang score increases, the probability of severe OSA rises. Using the STOP-Bang questionnaire, sleep clinicians can quickly and reliably identify those at risk of severe OSA and prioritize patients for polysomnography or out-of-center sleep testing. Similarly, surgical patients can be stratified for OSA severity according to their STOP-Bang scores.
      Several studies show that screening OSA with STOP-Bang questionnaire identifies patients with an increased incidence of postoperative complications.
      • Vasu T.S.
      • Doghramji K.
      • Cavallazzi R.
      • et al.
      Obstructive sleep apnea syndrome and postoperative complications: clinical use of the STOP-BANG questionnaire.
      • Corso R.M.
      • Petrini F.
      • Buccioli M.
      • et al.
      Clinical utility of preoperative screening with STOP-Bang questionnaire in elective surgery.
      • Chia P.
      • Seet E.
      • Macachor J.D.
      • Iyer U.S.
      • Wu D.
      The association of pre-operative STOP-BANG scores with postoperative critical care admission.
      Data from a prospective study of 3,452 patients show that patients identified as being at high risk of OSA by the STOP-Bang questionnaire had a higher rate of postoperative complications (9% vs 2% in patients with a low risk of OSA), difficult intubation (20% vs 9%), and difficult mask ventilation (23% vs 7%).
      • Corso R.M.
      • Petrini F.
      • Buccioli M.
      • et al.
      Clinical utility of preoperative screening with STOP-Bang questionnaire in elective surgery.
      The STOP-Bang score was positively associated with postoperative critical care admission.
      • Chia P.
      • Seet E.
      • Macachor J.D.
      • Iyer U.S.
      • Wu D.
      The association of pre-operative STOP-BANG scores with postoperative critical care admission.
      A prospective cohort study showed that untreated OSA was independently associated with more cardiopulmonary complications, particularly unplanned reintubations and myocardial infarction.
      • Abdelsattar Z.M.
      • Hendren S.
      • Wong S.L.
      • Campbell Jr., D.A.
      • Ramachandran S.K.
      The impact of untreated obstructive sleep apnea on cardiopulmonary complications in general and vascular surgery: a cohort study.
      In another retrospective study,
      • Mutter T.C.
      • Chateau D.
      • Moffatt M.
      • Ramsey C.
      • Roos L.L.
      • Kryger M.
      A matched cohort study of postoperative outcomes in obstructive sleep apnea: Could preoperative diagnosis and treatment prevent complications?.
      a diagnosis of OSA and prescription of CPAP therapy were associated with a reduction in postoperative cardiovascular complications. In a randomized controlled trial, perioperative auto-titrating positive airway pressure has been shown to prevent postoperative worsening of OSA and desaturation in patients newly diagnosed with OSA.
      • Liao P.
      • Luo Q.
      • Elsaid H.
      • Kang W.
      • Shapiro C.
      • Chung F.
      Perioperative auto-titrated continuous positive airway pressure treatment in surgical patients with obstructive sleep apnea: a randomized controlled trial.
      However, the randomized controlled trials did not show that the incidence of postoperative complications was reduced by perioperative auto-titrating positive airway pressure treatment,
      • Liao P.
      • Luo Q.
      • Elsaid H.
      • Kang W.
      • Shapiro C.
      • Chung F.
      Perioperative auto-titrated continuous positive airway pressure treatment in surgical patients with obstructive sleep apnea: a randomized controlled trial.
      • O’Gorman S.M.
      • Gay P.C.
      • Morgenthaler T.I.
      Does auto-titrating positive airway pressure therapy improve postoperative outcome in patients at risk for obstructive sleep apnea syndrome? A randomized controlled clinical trial.
      probably because of the small sample size (177 in the study of Liao et al
      • Liao P.
      • Luo Q.
      • Elsaid H.
      • Kang W.
      • Shapiro C.
      • Chung F.
      Perioperative auto-titrated continuous positive airway pressure treatment in surgical patients with obstructive sleep apnea: a randomized controlled trial.
      and 86 in the study of O’Gorman et al
      • O’Gorman S.M.
      • Gay P.C.
      • Morgenthaler T.I.
      Does auto-titrating positive airway pressure therapy improve postoperative outcome in patients at risk for obstructive sleep apnea syndrome? A randomized controlled clinical trial.
      ) and poor compliance with CPAP in these studies.
      • Guralnick A.S.
      • Pant M.
      • Minhaj M.
      • Sweitzer B.J.
      • Mokhlesi B.
      CPAP adherence in patients with newly diagnosed obstructive sleep apnea prior to elective surgery.
      • Liao P.
      • Luo Q.
      • Elsaid H.
      • Kang W.
      • Shapiro C.
      • Chung F.
      Perioperative auto-titrated continuous positive airway pressure treatment in surgical patients with obstructive sleep apnea: a randomized controlled trial.
      • O’Gorman S.M.
      • Gay P.C.
      • Morgenthaler T.I.
      Does auto-titrating positive airway pressure therapy improve postoperative outcome in patients at risk for obstructive sleep apnea syndrome? A randomized controlled clinical trial.
      • Nagappa M.
      • Mokhlesi B.
      • Wong J.
      • Wong D.T.
      • Kaw R.
      • Chung F.
      The effects of continuous positive airway pressure on postoperative outcomes in obstructive sleep apnea patients undergoing surgery: a systematic review and meta-analysis.
      Further research is needed to identify barriers to CPAP compliance in the perioperative setting.
      Currently no data are available to evaluate the impact of preoperative OSA screening and corresponding perioperative care measures on perioperative outcomes. We need to investigate prospectively whether a perioperative pathway incorporating preoperative OSA screening, perioperative OSA precautions, and postoperative treatment of OSA improves perioperative outcomes in patients with OSA.
      OSA is independently associated with a higher rate of long-term cardiovascular events after coronary artery bypass.
      • Uchoa C.H.
      • Danzi-Soares Nde J.
      • Nunes F.S.
      • et al.
      Impact of obstructive sleep apnea on cardiovascular events after coronary artery bypass surgery.
      Effective OSA screening in a preoperative clinic, followed by the initiation of CPAP treatment, may yield long-term health benefits.
      • Mehta V.
      • Subramanyam R.
      • Shapiro C.M.
      • Chung F.
      Health effects of identifying patients with undiagnosed obstructive sleep apnea in the preoperative clinic: a follow-up study.

      Limitations

      When using the STOP-Bang questionnaire, several key points should be taken into account. Although the STOP-Bang questionnaire has been validated in different populations, a selection bias might be present in some of the validation studies. For example, most patients in sleep clinics were referred because they were already suspected of having sleep-related issues. In studies targeting surgical patients, a self-selection bias from patients themselves may have occurred in that patients with preexisting sleep symptoms might be more willing to consent to an overnight PSG. Generally speaking, younger patients were more likely to decline the studies.
      • Chung F.
      • Yegneswaran B.
      • Liao P.
      • et al.
      STOP questionnaire: a tool to screen patients for obstructive sleep apnea.
      As a result of these potential selection biases, the high prevalence of OSA in the study populations may affect interpretation of the predictive parameters by presenting a seemingly inflated PPV. Although the STOP-Bang questionnaire is validated in multiple populations, it was less useful in identifying OSA patients in two distinct groups: the veteran population
      • Kunisaki K.M.
      • Brown K.E.
      • Fabbrini A.E.
      • Wetherbee E.E.
      • Rector T.S.
      STOP-BANG questionnaire performance in a Veterans Affairs unattended sleep study program.
      and patients with renal failure.
      • Nicholl D.D.
      • Ahmed S.B.
      • Loewen A.H.
      • et al.
      Diagnostic value of screening instruments for identifying obstructive sleep apnea in kidney failure.
      To ensure effective screening, validation of the STOP-Bang questionnaire in the specific target population is recommended. Since measurement tapes may not be consistently available in the physician’s office, and because of potential issues with measurement variability in neck circumference, these challenges may affect accuracy of the STOP-Bang score.

      Conclusions

      Studies have demonstrated that the STOP-Bang questionnaire is a concise, effective, and reliable OSA screening tool. It can facilitate efficient allocation of resources in both diagnosing and treating previously unrecognized OSA. The probability of moderate to severe OSA increases in direct proportion to the STOP-Bang score, which makes the questionnaire an easily used tool for identifying patients at high risk for OSA. Patients with a STOP-Bang score of 0 to 2 can be classified as being at low risk for moderate to severe OSA. Those with a STOP-Bang score of 5 to 8 can be classified as being at high risk for moderate to severe OSA. In patients with a STOP-Bang score of 3 or 4, the specific combinations of positive items should be examined further to ensure proper classification. If a combination of a STOP score ≥ 2 plus (BMI > 35 kg/m2 or male gender or neck circumference > 40 cm) or a STOP-Bang score ≥ 3 plus serum HCO3 ≥ 28 mmol/L is found, these patients can be further classified as being at high risk of moderate to severe OSA.

      Acknowledgments

      Author contributions: F. C. helped design the study, conduct the study, and write the manuscript and had overall responsibility for the study. H. R. A. helped design the study and write the manuscript. P. L. helped design the study, analyze the data, and write the manuscript.
      Financial/nonfinancial disclosures: None declared.
      Additional information: The e-Appendix can be found in the Supplemental Materials section of the online article.

      Supplementary Data

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