Epworth and STOP-BANG: The Evidence Behind the Tool

A 48-year-old bus driver from Mangaluru comes to the OPD for his blood pressure. He is on three drugs and it is still 156/98. He snores, his wife says, “like a lorry climbing a ghat”, and twice she has seen him stop breathing in his sleep. His BMI is 31 and his neck measures 42 cm. You hand him the Epworth questionnaire and he scores 8. “So he is not sleepy,” says the intern. “Can we forget about sleep apnoea?” This is an illustrative case, not a real patient.

By the end of this article you will know why the answer is no, and what the two scores on this tool each tell you.

1. Two Scores, Two Questions

The Epworth Sleepiness Scale measures how readily a person dozes in ordinary situations. STOP-BANG estimates the probability of moderate to severe obstructive sleep apnoea. They overlap only in the T item, for tiredness.

“Are tired and sleepy not the same?” No. A patient with anaemia or depression may be exhausted and still unable to nap. And sleepiness has many causes besides apnoea, while apnoea often exists without sleepiness. Our driver is the second kind.

2. Reading the Epworth Score

The total runs from 0 to 24. The tool uses the bands published on the official Epworth website:

The Indian guideline, INOSA 2014, defines excessive sleepiness as a score above 10, with a sensitivity of 49 per cent and a specificity of 80 per cent for sleep apnoea. Look at that sensitivity: half of the patients with apnoea are not sleepy by this measure. Our driver’s 8 is in the higher normal band.

3. Why a Normal Epworth Score Does Not Rule Out Apnoea

The doubt goes back to the scale’s own beginning (Johns 1991). As the tool used to say:

In the original Epworth paper, people who simply snored scored no higher than controls.

And it holds in our own patients. In a Delhi sleep clinic, STOP-BANG of 3 or more still detected 89 per cent of moderate to severe apnoea in patients with an Epworth score below 10, and those non-sleepy patients carried the same burden of cardiovascular and metabolic disease (Narwade 2024). So the intern’s instinct is understandable, and it is the common mistake: a low Epworth score answers the sleepiness question, not the apnoea question.

4. Scoring STOP-BANG

Each of the eight items scores one point: Snoring, Tiredness, Observed apnoea, high blood Pressure, BMI above 35, Age above 50, Neck above 40 cm and male Gender. The tool groups the total by Chung’s practical approach of 2016:

• 0 to 2 is low risk; 3 to 4 intermediate; 5 to 8 high.
• A total of 3 to 4 becomes high risk with 2 or more STOP items plus male sex, a BMI above 35 or a neck above 40 cm.
• A total of 3 or more with a serum bicarbonate of 28 mmol/L or more is also high risk. The bicarbonate also rises with diuretics, vomiting and chronic hypercapnia, so read it against the rest of the picture.

Our driver snores (1), his apnoeas have been seen (1), he has high blood pressure (1), his neck is above 40 cm (1) and he is a man (1). He is not tired by his own account, his BMI is below 35 and he is 48. That is 5: high risk.

“How reassuring is a low score?” Quite. A total of 3 or more detects 93 per cent of moderate to severe and 100 per cent of severe apnoea in surgical patients. That is why a low score is reassuring and a high one is not a diagnosis.

5. The BMI Item in Indian Patients

The B item scores only above 35, a figure few Indian patients reach, although apnoea occurs at lower BMI in Asians. In a multinational surgical cohort, a threshold above 27.5 was proposed for patients of Indian and Chinese ethnicity (Waseem 2021). How strong is that evidence? The tool used to give the cohort’s own numbers:

Only 14 of its 161 Indian patients had a BMI above 35, the improvement in discrimination was not statistically significant, and none of the centres was in India.

So the tool scores the published threshold of 35 and prints the alternative total at 27.5 beside it. It does not choose between them. On the alternative threshold our driver, at a BMI of 31, scores 6. The same study found a total of 4 or more the best balance of sensitivity and specificity in every ethnic group. The Asian cut-offs for overweight (23) and obesity (25) describe body habitus and are not part of STOP-BANG.

“How do I measure the neck?” Around the neck at the level of the Adam’s apple. The 2008 derivation and the 2016 practical approach score a neck above 40 cm; the current form on the official STOP-BANG website asks whether the collar is 16 inches or 40 cm or larger. The two readings differ only at exactly 40 cm, and the tool flags that case.

6. Where the Screen Matters Most

• Before surgery. STOP-BANG was derived in pre-operative clinics, and INOSA 2014 names it the most appropriate questionnaire there. Where a sleep study would delay surgery, INOSA allows it to be deferred, with a positive airway pressure device on standby and close post-operative monitoring.
• Resistant hypertension. Sleep apnoea with an apnoea-hypopnoea index above 15 was found in 64 per cent of patients with resistant hypertension, the commonest secondary cause in that series (Pedrosa 2011). Our driver is that patient.
• Hypothyroidism. INOSA asks that it be excluded as a secondary cause in anyone suspected of sleep apnoea.
• Driving. INOSA recommends that medical examiners refer drivers, pilots and heavy machinery operators with snoring, sleepiness or obesity for evaluation. The Form 1-A medical certificate under the Central Motor Vehicles Rules carries no item on sleep.

Back to Our Patient

His Epworth score of 8 says he is not unusually sleepy. His STOP-BANG of 5 says his risk of moderate to severe apnoea is high. He drives a bus, his blood pressure is resistant to three drugs, and he needs a sleep study. Check his thyroid function too. The questionnaire did its work; the low Epworth score did not close the question.

Try This

A 55-year-old woman with a BMI of 29 and a neck of 36 cm snores loudly and has treated hypertension. She is often tired, and nobody has seen her stop breathing. Her Epworth score is 12. What do the two scores say? Illustrative case.

Answer. Her Epworth of 12 is mild excessive daytime sleepiness on the website bands, and above 10 by INOSA. Her STOP-BANG is snoring 1, tiredness 1, pressure 1 and age 1: a total of 4, intermediate risk. She has three STOP items, but none of male sex, a BMI above 35 or a neck above 40 cm, so it stays intermediate. On the alternative BMI threshold of 27.5, she scores 5. A serum bicarbonate of 28 mmol/L or more would make her high risk.

Take-Home Points

• Epworth measures sleepiness; STOP-BANG estimates the risk of apnoea. They answer different questions.
• A normal Epworth score does not rule out sleep apnoea.
• A STOP-BANG below 3 is reassuring; 5 or more is high risk, not a diagnosis.
• In Indian patients the BMI item rarely scores; look at the alternative total the tool prints at 27.5.
• Screen before surgery, in resistant hypertension and in anyone who drives for a living.

For the blood pressure side of this patient, see Hypertension in the OPD: The Evidence Behind the Pathway; for the operation, Pre-Surgical Risk: The Evidence Behind the Pathway.

Declaration: the author built and maintains the tool. It is free to use, and is still in administrator preview, pending clinical review. The Epworth Sleepiness Scale is copyright of Dr Murray Johns and is licensed through Mapi Research Trust; its eight situations are not reproduced here. The figures in this article are those the tool carried in its Evidence tab on 5 November 2026, each from the source the tool names. The illustrative cases follow the tool’s rules; check the tool’s result for a real patient.

References

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