What is the role of the STOP BANG (Sleep Apnea screening tool) questionnaire in screening for Obstructive Sleep Apnea (OSA)?

STOP-BANG Questionnaire for OSA Screening

The STOP-BANG questionnaire is a validated screening tool with high sensitivity but low specificity that should be used to identify patients at risk for obstructive sleep apnea, but it cannot be used as a standalone diagnostic test and must be followed by confirmatory polysomnography or home sleep apnea testing. 1

What is STOP-BANG?

The STOP-BANG questionnaire consists of eight dichotomous (yes/no) items, with each positive response contributing one point for a total score ranging from 0-8 2:

• Snoring
• Tiredness/fatigue during daytime
• Observed apnea
• High blood Pressure
• BMI >35 kg/m²
• Age >50 years
• Neck circumference >40 cm
• Male Gender

2, 3

Score Interpretation and Risk Stratification

Basic Scoring Approach

• Score 0-2: Low risk for moderate-to-severe OSA 4
• Score 3-4: Intermediate risk - requires additional stratification 2, 4
• Score 5-8: High risk for moderate-to-severe OSA 4

Enhanced Stratification for Scores 3-4

For patients with intermediate scores (3-4), classify as high risk for moderate-to-severe OSA if they meet any of these criteria 4:

• STOP score ≥2 + BMI >35 kg/m²
• STOP score ≥2 + male gender
• STOP score ≥2 + neck circumference >40 cm
• Serum bicarbonate (HCO₃⁻) ≥28 mmol/L 4, 5

Diagnostic Performance

Sensitivity and Specificity

The STOP-BANG questionnaire demonstrates high sensitivity but problematic specificity 1:

• Sensitivity: 66-79% for moderate-to-severe OSA (AHI ≥15), improving to 92.9-100% when combined with clinical parameters 6, 3
• Specificity: Only 27-37% at score ≥3, which improves to 79.7-85.2% when combined with serum bicarbonate ≥28 mmol/L 5
• Negative predictive value: 85% for moderate-to-severe OSA and 94.8% for severe OSA 6

Critical Limitation

All clinical prediction models, including STOP-BANG, result in more than 100 false negatives per 1,000 patients—a number deemed clearly excessive for standalone diagnostic use. 1

Clinical Applications

Preoperative Screening

STOP-BANG is particularly valuable in the perioperative setting 1:

• In surgical patients, the questionnaire correctly identified 92.5% and 93.1% of patients with moderate-severe OSA that were missed by anesthesiologists and surgeons respectively 1
• OSA increases risk of postoperative pulmonary complications 2.5-fold, and increases risk of myocardial infarction and atrial fibrillation 1
• Preoperative OSA screening is reasonable before noncardiac surgery, especially in patients with cardiovascular disease 1

General Population Screening

The questionnaire maintains moderate sensitivity (66.2-69.2%) and specificity (67.1-74.7%) in general population screening, with high negative predictive values making it useful for ruling out severe OSA 6

Mandatory Next Steps After Positive Screening

Never rely solely on STOP-BANG score for diagnosis—confirmatory testing is mandatory 2:

1. Gold standard: In-laboratory polysomnography (PSG) remains the definitive diagnostic test 2, 7
2. Alternative: Home sleep apnea testing (HSAT) may be considered for patients with high pretest probability when PSG is not readily available 2, 7

Improving Specificity: Two-Step Screening Process

To reduce false positives, use this algorithmic approach 5:

Step 1: Administer STOP-BANG questionnaire
Step 2: For patients with score ≥3, obtain serum bicarbonate level

• If HCO₃⁻ ≥28 mmol/L: High specificity (79.7-85.2%) for moderate-to-severe OSA, proceed urgently to confirmatory testing 5
• If HCO₃⁻ <28 mmol/L: Lower specificity, but still warrants confirmatory testing based on clinical context 5

Critical Pitfalls to Avoid

• Do not diagnose OSA based on STOP-BANG alone—the American Academy of Sleep Medicine explicitly states it should not be used as a standalone diagnostic tool due to limited specificity 1, 2
• Recognize the high false-positive rate—at score ≥3, specificity is only 27-37% without additional stratification 5
• Be aware of validation limitations—the questionnaire was primarily validated in middle-aged, predominantly male, obese surgical populations, which may affect accuracy in other demographics including adolescents and females 7
• Do not use lower BMI cutoffs for Asian populations—the original BMI cutoff of >35 kg/m² performs adequately and lower cutoffs (27.5 or 30) do not significantly improve performance 6