STOP-BANG Score Calculator

Patients with undiagnosed or untreated OSA face a significantly increased risk of perioperative complications. The collapsible upper airway that characterises OSA makes these patients vulnerable at multiple points during the surgical journey.

• Airway management: OSA is associated with difficult mask ventilation and difficult intubation. Anatomical features contributing to OSA (retrognathia, large tongue base, short thyromental distance, increased neck circumference) overlap with predictors of difficult airway management.
• Opioid sensitivity: OSA patients have heightened sensitivity to opioid-induced respiratory depression. Even standard doses of postoperative opioids can precipitate prolonged apnoeas and desaturation.
• Postoperative respiratory events: Oxygen desaturation, re-intubation, ICU transfer, and cardiac arrhythmias are all more frequent in OSA patients, particularly after upper abdominal and airway surgery.
• Postoperative monitoring: High-risk patients may require continuous pulse oximetry, supplemental oxygen, CPAP continuation, and avoidance of supine positioning postoperatively.

Society of Anesthesia and Sleep Medicine (SASM) guidelines recommend screening all surgical patients with STOP-BANG and implementing OSA-specific perioperative protocols for those who screen positive.

OSA is an independent risk factor for several cardiovascular conditions. The intermittent hypoxia, intrathoracic pressure swings, and sympathetic surges associated with repetitive apnoeic episodes drive a cascade of pathophysiological changes including endothelial dysfunction, systemic inflammation, and oxidative stress.

• Hypertension: OSA is the most common identifiable cause of secondary or resistant hypertension. Treatment with CPAP has been shown to modestly reduce blood pressure, particularly in patients with severe OSA and good CPAP adherence.
• Atrial fibrillation: OSA is associated with a 2–4 fold increased risk of AF and higher recurrence rates after cardioversion or ablation. Screening for OSA is recommended in AF management guidelines.
• Heart failure: Both OSA and central sleep apnoea are prevalent in patients with heart failure. OSA may worsen cardiac function through increased afterload and sympathetic activation.
• Stroke: Moderate-to-severe OSA approximately doubles stroke risk, and OSA is highly prevalent (60–80%) among stroke survivors.

These associations underscore the importance of screening beyond the perioperative setting — STOP-BANG can be applied in cardiology, hypertension, and stroke clinics.

A positive STOP-BANG screen should be followed by objective testing to confirm and grade OSA severity. Two main testing modalities are available:

• In-laboratory polysomnography (PSG): The reference standard. Records EEG, EOG, EMG, airflow, respiratory effort, oxygen saturation, ECG, body position, and limb movements. Provides the AHI, respiratory disturbance index (RDI), and data on sleep architecture. Recommended when there is suspicion of comorbid sleep disorders (central sleep apnoea, periodic limb movement disorder, narcolepsy) or when HSAT is inconclusive.
• Home sleep apnoea testing (HSAT): A simplified, portable test typically measuring airflow, respiratory effort, and oxygen saturation. Appropriate for patients with a high pretest probability of moderate-to-severe OSA (i.e., STOP-BANG ≥ 5) without significant comorbidities. HSAT may underestimate severity because total sleep time is estimated rather than measured, and it cannot identify central apnoeas reliably.

OSA severity is graded by the AHI: mild (5–14 events/hour), moderate (15–29 events/hour), and severe (≥ 30 events/hour). Treatment decisions incorporate both AHI and symptom burden.

Treatment of OSA is guided by severity, symptom burden, patient preference, and comorbidities. CPAP (continuous positive airway pressure) remains the first-line treatment for moderate-to-severe OSA and is the standard of care in the perioperative setting for known OSA patients.

• CPAP: Delivers positive pressure via a nasal or full-face mask, acting as a pneumatic splint for the upper airway. Highly effective when used consistently. Adherence remains the primary challenge — approximately 50% of patients discontinue CPAP within 1–3 years.
• Mandibular advancement devices (MAD): Custom-fitted oral appliances that protrude the mandible forward, increasing the retroglossal airway space. Recommended for mild-to-moderate OSA or for patients who cannot tolerate CPAP. Less effective than CPAP for severe disease.
• Positional therapy: Effective in patients with predominantly supine-dependent OSA. Devices or techniques to maintain lateral sleeping position can reduce AHI significantly in selected patients.
• Surgical options: Uvulopalatopharyngoplasty (UPPP), maxillomandibular advancement, and hypoglossal nerve stimulation are options for selected patients who fail conservative therapy. Bariatric surgery may be considered when severe obesity is the primary driver of OSA.
• Weight management: Weight loss of ≥ 10% can substantially reduce AHI and may resolve mild OSA entirely. This is a key adjunctive treatment in overweight and obese patients.

Several OSA screening questionnaires exist. The STOP-BANG has emerged as the most widely validated and recommended, but understanding alternatives helps contextualise its strengths and limitations.

• STOP questionnaire: The four-question precursor to STOP-BANG (Snoring, Tiredness, Observed apnoeas, Pressure). Simpler to administer but substantially less sensitive than STOP-BANG, particularly for moderate-to-severe OSA.
• Epworth Sleepiness Scale (ESS): An eight-item questionnaire assessing daytime sleepiness (not OSA specifically). The ESS measures symptom burden but has poor sensitivity and specificity for predicting OSA on polysomnography. It is complementary to STOP-BANG — a high STOP-BANG with a high ESS suggests both high OSA probability and significant symptom impact.
• Berlin Questionnaire: A 10-item questionnaire categorising patients by snoring behaviour, daytime somnolence, and hypertension/obesity. More complex to administer and score than STOP-BANG. Comparable sensitivity but lower specificity in most head-to-head comparisons.
• NoSAS Score: A newer scoring system (Neck circumference, Obesity, Snoring, Age, Sex) that uses weighted components. Shows promising discrimination in some populations but has less validation data than STOP-BANG, particularly in the perioperative setting.

Current SASM and ASA guidelines endorse STOP-BANG as the preferred screening tool for the perioperative context due to its combination of high sensitivity, ease of administration, and extensive validation.

The most common error is interpreting a high STOP-BANG score as equivalent to a diagnosis of OSA. STOP-BANG is a screening instrument with intentionally high sensitivity — it is designed to cast a wide net and minimise false negatives. The trade-off is a significant false-positive rate: a substantial proportion of patients scoring 3–4 will have a normal AHI on polysomnography.

A positive screen should prompt further evaluation (sleep study), not automatic labelling of the patient as having OSA. Conversely, in the perioperative setting, a positive screen can and should trigger precautionary measures even before formal diagnosis, because the consequences of unrecognised OSA during anaesthesia are potentially serious.

Because three of the eight criteria are demographic (age > 50, male sex, BMI > 35), certain patient groups will automatically score 2–3 points without any sleep-related symptoms. An overweight male patient over 50 with treated hypertension scores 4 by demographics alone — placing him in the intermediate-risk category regardless of whether he has any sleep-related symptoms.

This demographic loading reduces specificity in older, male, and obese populations. The BANG refinement (counting the number of positive BANG criteria in intermediate scorers) can help improve specificity. Additionally, clinicians should always weigh the STOP components (symptom-based) more heavily when making clinical decisions about referral urgency — a patient with witnessed apnoeas and excessive daytime sleepiness warrants more urgent evaluation than an asymptomatic patient scoring on demographics alone.

Four of the eight STOP-BANG items rely on patient self-report (snoring, tiredness, observed apnoeas, hypertension). Patients who sleep alone may be unaware of loud snoring or apnoeic episodes. Cultural factors, health literacy, and the tendency to minimise symptoms can all affect accuracy. Daytime tiredness is non-specific and overlaps with many other conditions including depression, anaemia, hypothyroidism, and poor sleep hygiene.

Where possible, corroborate the snoring and observed apnoea items with a bed partner or family member. If the patient sleeps alone and is unsure, the clinician should consider this an uncertain rather than negative response and exercise clinical judgement about the overall risk profile.

A positive STOP-BANG score is only clinically useful if it changes management. Screening patients before surgery but failing to implement OSA-specific precautions negates the benefit of screening. Common failures include: not communicating the result to the anaesthetist, not adjusting the analgesic plan, not arranging postoperative monitoring, and not ensuring CPAP availability for patients with known OSA.

Perioperative OSA protocols should include: preoperative discussion of airway management strategy, use of multimodal analgesia to minimise opioids, regional or neuraxial anaesthesia where appropriate, extubation when fully awake, avoidance of supine positioning in recovery, continuous pulse oximetry for at least the first postoperative night, and CPAP application for patients with diagnosed OSA or high STOP-BANG scores.

The STOP-BANG score assigns points for male sex and BMI > 35, which can lead to lower scores in women and non-obese patients who nevertheless have clinically significant OSA. Approximately 6% of women and a significant proportion of lean individuals with unfavourable craniofacial anatomy have moderate-to-severe OSA that may be missed by the questionnaire.

Clinicians should maintain a low threshold for further evaluation when patients present with symptoms suggestive of OSA — particularly witnessed apnoeas, choking awakenings, or refractory hypertension — even if the STOP-BANG score falls in the low-risk range. No screening tool is perfect, and clinical suspicion should always take precedence over a numerical score.