A Simple and Reliable Tool: STOP-BANG in Assessing Obstructive Sleep Apnea.
Introduction
The STOP-BANG questionnaire is a tool that screens for obstructive sleep apnea (OSA, not for central sleep apnea) and is one of the most recognized screening tools for OSA. It is a screening tool, thus not diagnostic, and depending on the outcome, advise the assessor on the next step. MD Calc mentions that one of the pitfalls is that the STOP-BANG questionnaire does not fully work for the obstetrical population, a subgroup found to be at an increased risk of OSA. The screening tool was created by Frances Chung (MBBS, LMCC, FRCPC). Dr Chung is a professor in the department of anaesthesia at the University of Toronto, Canada. She is also a clinical researcher at the Krembil Research Institute and a senior staff anesthesiologist at the University Health Network-Mount Sinai Hospital. Dr Chung’s research interests include obstructive sleep apnea as well as ambulatory and geriatric anaesthesia.
STOP-BANG
S – Snoring
The first question of the questionnaire is to ask the patient if they snore. It is essential to somehow subjectively quantify the loudness of the snoring as it can give a general idea of the snoring. For example, is it louder than talking, is it loud enough to be heard through a door, or is it so loud that no one near can sleep?
No 0, Yes +1
T – tiredness
Patients suffering from OSA typically present with lethargy, tiredness or sleepiness during the day. This is due to its pathophysiology (explained below), where a patient oscillates between sleep and wakefulness. Eckert DJ and Malhotra A noted that in severe cases, patients might wake up 56 times per hour (waking up does not describe being completely awake and aware, just breaking the sleep cycle as many patients are completely unaware).
No 0, Yes +1
O – Observed
Ask the patient if anyone has observed them having an apnea episode. An apnea episode is when someone, while they sleep, completely stop breathing for longer than intended (this can range from a few to 90 seconds). After an apnea, the person typically wakes up (not fully conscious but enough to disrupt sleep).
No 0, Yes +1
P – pressure (blood pressure)
Is there any evidence of high blood pressure? Is the patient being treated for high blood pressure?
No 0, Yes +1
B – Body Mass Index (BMI)
A BMI below ≤35 kg/m² corresponds to 0 points.
A BMI greater than >35 kg/m² corresponds to 1 point.
A – Age
Below ≤50 years corresponds to 0 points.
Above >50 years corresponds to 1 point.
N – Neck circumference
A neck circumference below ≤40 cm corresponds to 0 points.
Above >40 cm corresponds to 1 point.
G – Gender
Male - 1 point.
Female - 0 points.
Interpretation
0-2: low risk of OSA
3-8: high risk of OSA
Why is OSA important to screen
One in four men over the age of 30 years have some degree of sleep apnoea. It is a treatable condition where the main focus of treatment is lifestyle modifications (increasing physical activity, losing weight and cutting back on alcohol/smoking) and using a CPAP machine. Obstructive sleep apnea occurs when a person’s throat is partially or completely blocked, resulting in a person to stop breathing. The person thus wakes up often unaware, and when they do wake up, they feel tired and not rested. A person may have interrupted sleep up to hundreds of times per night. Having a lack of sleep and continuous stress from disrupted sleep have been linked to many complications.
The pathophysiology of OSA can be a bit complicated, but essentially this occurs:
There is an anatomical predisposition to airway collapse, such as increased adipose tissue, compromised craniofacial structures, decreased lung volume, or airway oedema.
A person sleeps → there is a decrease in the tonic activity of upper airway dilator muscles.
The upper airway closes → leads to ↓ O2 + ↑ CO2 + ↓pH in the blood.
Chemoreceptors (peripheral and central) feedback to the medulla and the hypothalamus.
↑ sympathetic output → arousal from sleep (the person wakes up) → resumption of airflow.
Normalisation of O2, CO2 and pH.
However, the ventilator may overshoot → resulting in hypocapnia, which is picked up by the chemoreceptors.
Results in ↓ motor input to airway / respiratory muscles.
This leads to apnoea once again, where the cycle keeps repeating.
Apart from the lack of sleep, which is linked to bad health, a significant complication of OSA is that it can cause cardiovascular problems such as high blood pressure, irregular heart rhythms, heart attacks and essentially can lead to heart failure. In addition, stress hormones can be released due to the constant changes in sleeping and awake state. Furthermore, OSA has been linked to increasing the risks of metabolic syndrome, diabetes, strokes, poor memory and lack of concentration, headaches, psychological changes (moodiness, depression and personality change), lack of interest in sex, and impotence in men. It is thus essential to be diagnosed and treated for OSA.
OSA is accentuated with people who are/have:
Older
Male
Snores
Overweight
Family history of sleep apnea
Certain medications
Alcohol, sedatives or tranquillizers
Allergies
Upper respiratory tract infections, sinusitis et cetera.
Large neck
Smoking
Malformation of the airway passage includes a tumour, septum deviation, large tongue, goitre, etc.
The next step
Talk to your GP if you experience these symptoms and perpetual sleepiness. Your GP may refer you to a specialist and a sleep study. A sleep study is beneficial as it measures brain signals, oxygen levels in the blood, sleep position and limb movements, heart rate, breathing and snoring.
After a proper diagnosis, treatment may begin, which includes lifestyle modifications and the use of a CPAP machine. You may be referred to the dietician (helping in having the correct diet), dentist (dental devices), psychologist (helping in achieving goals), sports physiotherapist and the surgeon team (in case of anatomical obstructions).
Published 15th June 2021. Last reviewed 1st December 2021.
Reference
Better Health authors. Sleep apnea. Better Health website. https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/sleep-apnoea. Reviewed October, 2021. Accessed December 1, 2021.
Dempsey JA, Veasey SC, Morgan BJ, O'Donnell CP. Pathophysiology of sleep apnea. Physiol Rev. 2010;90(1): 47-112. doi:10.1152/physrev.00043.2008
Eckert DJ, Malhotra A. Pathophysiology of adult obstructive sleep apnea. Proc Am Thorac Soc. 2008;5(2):144-153. doi:10.1513/pats.200707-114MG
Health Direct authors. Sleep Apnea. Health Direct website. https://www.healthdirect.gov.au/sleep-apnoea. Reviewed January, 2020. Accessed December 1, 2021.
Mayo Clinic authors. Sleep Apnoea. Mayo Clinic website. https://www.mayoclinic.org/diseases-conditions/sleep-apnea/symptoms-causes/syc-20377631. Reviewed July, 2020. Accessed December 1, 2021.
Meyer MJ. STOP-BANG Score for Obstructive Sleep Apnea. MD Calc website. https://www.mdcalc.com/stop-bang-score-obstructive-sleep-apnea#evidence. Accessed November 27, 2021.
