NIHR Signal A self-completed questionnaire may help alert people with sleep apnoea to the need for proper diagnosis

Published on 23 March 2016

More use could be made of the STOP-Bang questionnaire as a self-completed ‘first check’ for detecting obstructive sleep apnoea or in selected people before surgery. The downside is that a high rate of false positives, identified by this review, means that many people in the community without the condition might test positive and receive unnecessary attention. This might not be a problem, as this common sleep-related breathing condition is under-diagnosed, but the consequences will need further evaluation. Sleep apnoea is associated with various health risks, including accidents due to daytime sleepiness, so once a firm diagnosis is made, people can benefit from the treatments available and anaesthetists can be prepared before surgery.

This review assessed the performance of the STOP-Bang questionnaire when used by people referred to sleep clinics, or before surgery. Compared with formal diagnosis in a sleep clinic, STOP-Bang demonstrated good sensitivity for detecting sleep apnoea in people with the condition (90%) but was not specific enough to be useful for making a diagnosis on its own (specificity 49%).

Questionnaires such as this could be a convenient first check for identifying an underdiagnosed condition, but is unlikely to take the place of a clinical assessment or reduce the use of sleep clinics for diagnosis. This study was conducted in hospital sleep clinics on people who are more likely to have sleep apnoea. The usefulness of the test in an unselected primary care population may be different and needs fuller assessment because false positives generated by use of the test could become a burden to the health system.

Other questionnaires exist. At present, UK guidance does not cover systematic screening for the condition, or advise which questionnaire is best for diagnosis or triage. Further research comparing the clinical and cost effectiveness and acceptability of different tools in UK settings and in primary care is needed before changing guidance or practice.

A self-completed questionnaire may help alert people with sleep apnoea to the need for proper diagnosis

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Why was this study needed?

Sleep apnoea is a condition where the throat relaxes during sleep and temporarily obstructs breathing, disturbing sleep. It is thought to affect up 1.5 million people in the UK, of whom 80% are undiagnosed. Research by the Office of Health Economics for the British Lung Foundation found that improving awareness, diagnosis and treatment of sleep apnoea could save the NHS up to £28 million and prevent up to 40,000 road traffic accidents a year.

Although sleep apnoea is common, its symptoms are not easy to detect yourself. A technique called polysomnography is used for reliable diagnosis, but is time-consuming, relies on sleep experts and is not available in all areas of the UK. It involves being monitored overnight at a sleep laboratory or using monitoring equipment at home, including breathing and blood oxygen sensors.

A simple, effective questionnaire could be a cheap and convenient way to identify people at risk of the condition, for example in primary care or before having surgery, so the reviewers here set out to see how accurate this one was. Other screening questionnaires exist, for example the Berlin scale, GASP (Graduated Apnoea Screening Protocol), and for sleepiness, the Epworth Sleepiness Scale. This review did not address comparisons between screening questionnaires, although previous reviews have shown mixed but generally favourable performance of STOP-Bang.

What did this study do?

This was a systematic review of 17 diagnostic test accuracy studies, including 9,206 participants. The findings of 11 studies of people referred to sleep laboratories and three studies of patients being screened before operations were pooled in meta-analysis. These two groups of people differed by risk of sleep apnoea (high for clinical referrals, compared with a lower risk for pre-operative patients), and in test availability (definitive overnight tests at sleep clinics, compared with need for rapid, accurate screening before surgery). However, the majority of the participants were middle aged men with high BMI.

The included studies examined STOP-Bang questionnaire performance by measuring the proportion detected compared with the most reliable diagnosis, directly measuring low oxygen breathing episodes during sleep, in a sleep laboratory (polysomnography).

The review was carried out to a high standard, using PRISMA guidelines. Applicability of the findings to UK care was limited by including only one, modestly sized UK study, which took place in a hospital.

What did it find?

  • Pooled findings from the 11 sleep clinic studies (85% prevalence of sleep apnoea) found that the proportion of people correctly detected by the questionnaire, set at a three or more cut-off, was 90% (95% confidence interval [CI] 88% to 91%). The definition of sleep apnoea was made on a subsequent recording of apnoea-hypopnoea index [AHI] of 5 or more on polysomnography.
  • In these sleep clinic studies the pooled specificity was 49% (95% CI 45% to 54%). This is the chance that someone without the condition is correctly detected as being free from sleep apnoea. The result suggests that more than half (51%) of people without sleep apnoea might be unnecessarily referred for further tests following the questionnaire.
  • Pooled findings from the three pre-operative studies (a lower prevalence of 68% compared to sleep clinics) found similar results: sensitivity 84% and specificity 43% for sleep apnoea (two studies).
  • In one general population study (with the lowest prevalence of 12.7% for moderate-to-severe sleep apnoea) the sensitivity was 88% to detect moderate-to-severe OSA, the specificity remained at 30% but the positive predictive value fell to 16%. This means that for those testing positive on the questionnaire only 16% actually will turn out to have sleep apnoea if tested in a sleep lab later.
  • In general, the higher the STOP-Bang score cut-off, the higher the probability of having moderate to severe sleep apnoea, but this varied by study setting and underlying prevalence of the condition. For example, in pooled results from the sleep clinic studies, a STOP-Bang score of 3 had a 25% likelihood of having severe sleep apnoea, whereas the pooled results from pre-operative studies showed that people with a score of 3 had a15% likelihood of having severe sleep apnoea.

What does current guidance say on this issue?

NICE guidance from 2008 states that diagnosis of sleep apnoea should be carried out by a specialist service. It does not cover population screening for the condition, which is not as yet a policy assessed or recommended by the UK National Screening Committee.

US guidance from 2014 on the management of people undergoing surgery, notes that the performance of sleep apnoea screening questionnaires varied widely between studies. It recommends drawing diagnostic information from sources such as clinical examination, medical history and sleep studies if sleep apnoea is suspected.

What are the implications?

A simple, effective questionnaire such as STOP-Bang could help identify people at risk of this under-diagnosed condition, but over half of people who test positive using the tool in any setting do not have sleep apnoea. If the questionnaire is used in primary care, without a clinical suspicion of sleep apnoea, many people many people may be referred onwards to scarce specialist sleep clinic resources.

So far there has been limited UK-based research. Most studies assessing the performance of sleep apnoea screening questionnaires have been carried out in North America. Before implementing in the NHS, further research is needed to investigate how the tool performs in UK settings, such as in primary care and in healthy populations before planned surgery. Comparison of STOP-Bang’s performance against other scales is also needed to assess their relative clinical and cost effectiveness and acceptability in the UK.

Citation and Funding

Nagappa M, Liao P, Wong J, et al. Validation of the STOP-Bang questionnaire as a screening tool for obstructive sleep apnea among different populations: a systematic review and meta-analysis. PLoS One. 2015;10(12):e0143697.

This work was supported by University Health Network Foundation and Department of Anesthesia, Toronto Western Hospital, University Health Network, University of Toronto.
No funding bodies had any role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Bibliography

Abrishami A, Khajehdehi A, Chung F. A systematic review of screening questionnaires for obstructive sleep apnea. Can J Anesth. 2010;57:423–38.

BLF. Obstructive sleep apnoea (OSA) [internet]. London: British Lung Foundation; 2014.

Cowan DC, Allardice G, MacFarlane D, et al. Predicting sleep disordered breathing in outpatients with suspected OSA. BMJ open. 2014;4(4):e004519.

Gross JB, Apfelbaum JL, Caplan RA, et al. Practice guidelines for the perioperative management of patients with obstructive sleep apnea. An updated report by the American Society of Anesthesiologists Task Force on perioperative management of patients with obstructive sleep apnea. Anesthesiology. 2014;120:268–86.

Johns MW. A new method for measuring daytime sleepiness: The Epworth Sleepiness Scale. Sleep 1991; 14:540-5.

Netzer NC, Stoohs RA, Netzer CM, et al. Using the Berlin Questionnaire to identify patients at risk for the sleep apnoea syndrome. Ann Intern Med. 1999;131(7):485-91.

NHS Choices. Obstructive sleep apnoea [internet]. Leeds: NHS Choices; 2014.

NICE. Continuous positive airway pressure for the treatment of obstructive sleep apnoea/hypopnoea syndrome. TA139. London: National Institute for Health and Care Excellence; 2008.

Ramachandran SK, Josephs LA. A meta-analysis of clinical screening tests for obstructive sleep apnea. Anesthesiology. 2009;110:928–39.

Rejón-Parrilla JC, Garau M, Jon Sussex J. Obstructive sleep apnoea health economics report. London: British Lung Foundation, Office for Health Economics; 2014.

Why was this study needed?

Sleep apnoea is a condition where the throat relaxes during sleep and temporarily obstructs breathing, disturbing sleep. It is thought to affect up 1.5 million people in the UK, of whom 80% are undiagnosed. Research by the Office of Health Economics for the British Lung Foundation found that improving awareness, diagnosis and treatment of sleep apnoea could save the NHS up to £28 million and prevent up to 40,000 road traffic accidents a year.

Although sleep apnoea is common, its symptoms are not easy to detect yourself. A technique called polysomnography is used for reliable diagnosis, but is time-consuming, relies on sleep experts and is not available in all areas of the UK. It involves being monitored overnight at a sleep laboratory or using monitoring equipment at home, including breathing and blood oxygen sensors.

A simple, effective questionnaire could be a cheap and convenient way to identify people at risk of the condition, for example in primary care or before having surgery, so the reviewers here set out to see how accurate this one was. Other screening questionnaires exist, for example the Berlin scale, GASP (Graduated Apnoea Screening Protocol), and for sleepiness, the Epworth Sleepiness Scale. This review did not address comparisons between screening questionnaires, although previous reviews have shown mixed but generally favourable performance of STOP-Bang.

What did this study do?

This was a systematic review of 17 diagnostic test accuracy studies, including 9,206 participants. The findings of 11 studies of people referred to sleep laboratories and three studies of patients being screened before operations were pooled in meta-analysis. These two groups of people differed by risk of sleep apnoea (high for clinical referrals, compared with a lower risk for pre-operative patients), and in test availability (definitive overnight tests at sleep clinics, compared with need for rapid, accurate screening before surgery). However, the majority of the participants were middle aged men with high BMI.

The included studies examined STOP-Bang questionnaire performance by measuring the proportion detected compared with the most reliable diagnosis, directly measuring low oxygen breathing episodes during sleep, in a sleep laboratory (polysomnography).

The review was carried out to a high standard, using PRISMA guidelines. Applicability of the findings to UK care was limited by including only one, modestly sized UK study, which took place in a hospital.

What did it find?

  • Pooled findings from the 11 sleep clinic studies (85% prevalence of sleep apnoea) found that the proportion of people correctly detected by the questionnaire, set at a three or more cut-off, was 90% (95% confidence interval [CI] 88% to 91%). The definition of sleep apnoea was made on a subsequent recording of apnoea-hypopnoea index [AHI] of 5 or more on polysomnography.
  • In these sleep clinic studies the pooled specificity was 49% (95% CI 45% to 54%). This is the chance that someone without the condition is correctly detected as being free from sleep apnoea. The result suggests that more than half (51%) of people without sleep apnoea might be unnecessarily referred for further tests following the questionnaire.
  • Pooled findings from the three pre-operative studies (a lower prevalence of 68% compared to sleep clinics) found similar results: sensitivity 84% and specificity 43% for sleep apnoea (two studies).
  • In one general population study (with the lowest prevalence of 12.7% for moderate-to-severe sleep apnoea) the sensitivity was 88% to detect moderate-to-severe OSA, the specificity remained at 30% but the positive predictive value fell to 16%. This means that for those testing positive on the questionnaire only 16% actually will turn out to have sleep apnoea if tested in a sleep lab later.
  • In general, the higher the STOP-Bang score cut-off, the higher the probability of having moderate to severe sleep apnoea, but this varied by study setting and underlying prevalence of the condition. For example, in pooled results from the sleep clinic studies, a STOP-Bang score of 3 had a 25% likelihood of having severe sleep apnoea, whereas the pooled results from pre-operative studies showed that people with a score of 3 had a15% likelihood of having severe sleep apnoea.

What does current guidance say on this issue?

NICE guidance from 2008 states that diagnosis of sleep apnoea should be carried out by a specialist service. It does not cover population screening for the condition, which is not as yet a policy assessed or recommended by the UK National Screening Committee.

US guidance from 2014 on the management of people undergoing surgery, notes that the performance of sleep apnoea screening questionnaires varied widely between studies. It recommends drawing diagnostic information from sources such as clinical examination, medical history and sleep studies if sleep apnoea is suspected.

What are the implications?

A simple, effective questionnaire such as STOP-Bang could help identify people at risk of this under-diagnosed condition, but over half of people who test positive using the tool in any setting do not have sleep apnoea. If the questionnaire is used in primary care, without a clinical suspicion of sleep apnoea, many people many people may be referred onwards to scarce specialist sleep clinic resources.

So far there has been limited UK-based research. Most studies assessing the performance of sleep apnoea screening questionnaires have been carried out in North America. Before implementing in the NHS, further research is needed to investigate how the tool performs in UK settings, such as in primary care and in healthy populations before planned surgery. Comparison of STOP-Bang’s performance against other scales is also needed to assess their relative clinical and cost effectiveness and acceptability in the UK.

Citation and Funding

Nagappa M, Liao P, Wong J, et al. Validation of the STOP-Bang questionnaire as a screening tool for obstructive sleep apnea among different populations: a systematic review and meta-analysis. PLoS One. 2015;10(12):e0143697.

This work was supported by University Health Network Foundation and Department of Anesthesia, Toronto Western Hospital, University Health Network, University of Toronto.
No funding bodies had any role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Bibliography

Abrishami A, Khajehdehi A, Chung F. A systematic review of screening questionnaires for obstructive sleep apnea. Can J Anesth. 2010;57:423–38.

BLF. Obstructive sleep apnoea (OSA) [internet]. London: British Lung Foundation; 2014.

Cowan DC, Allardice G, MacFarlane D, et al. Predicting sleep disordered breathing in outpatients with suspected OSA. BMJ open. 2014;4(4):e004519.

Gross JB, Apfelbaum JL, Caplan RA, et al. Practice guidelines for the perioperative management of patients with obstructive sleep apnea. An updated report by the American Society of Anesthesiologists Task Force on perioperative management of patients with obstructive sleep apnea. Anesthesiology. 2014;120:268–86.

Johns MW. A new method for measuring daytime sleepiness: The Epworth Sleepiness Scale. Sleep 1991; 14:540-5.

Netzer NC, Stoohs RA, Netzer CM, et al. Using the Berlin Questionnaire to identify patients at risk for the sleep apnoea syndrome. Ann Intern Med. 1999;131(7):485-91.

NHS Choices. Obstructive sleep apnoea [internet]. Leeds: NHS Choices; 2014.

NICE. Continuous positive airway pressure for the treatment of obstructive sleep apnoea/hypopnoea syndrome. TA139. London: National Institute for Health and Care Excellence; 2008.

Ramachandran SK, Josephs LA. A meta-analysis of clinical screening tests for obstructive sleep apnea. Anesthesiology. 2009;110:928–39.

Rejón-Parrilla JC, Garau M, Jon Sussex J. Obstructive sleep apnoea health economics report. London: British Lung Foundation, Office for Health Economics; 2014.

Validation of the STOP-Bang Questionnaire as a Screening Tool for Obstructive Sleep Apnea among Different Populations: A Systematic Review and Meta-Analysis

Published on 15 December 2015

Nagappa, M.,Liao, P.,Wong, J.,Auckley, D.,Ramachandran, S. K.,Memtsoudis, S.,Mokhlesi, B.,Chung, F.

PLoS One Volume 10 , 2015

BACKGROUND: Diagnosing obstructive sleep apnea (OSA) is clinically relevant because untreated OSA has been associated with increased morbidity and mortality. The STOP-Bang questionnaire is a validated screening tool for OSA. We conducted a systematic review and meta-analysis to determine the effectiveness of STOP-Bang for screening patients suspected of having OSA and to predict its accuracy in determining the severity of OSA in the different populations. METHODS: A search of the literature databases was performed. Inclusion criteria were: 1) Studies that used STOP-Bang questionnaire as a screening tool for OSA in adult subjects (>18 years); 2) The accuracy of the STOP-Bang questionnaire was validated by polysomnography-the gold standard for diagnosing OSA; 3) OSA was clearly defined as apnea/hypopnea index (AHI) or respiratory disturbance index (RDI) >/= 5; 4) Publications in the English language. The quality of the studies were explicitly described and coded according to the Cochrane Methods group on the screening and diagnostic tests. RESULTS: Seventeen studies including 9,206 patients met criteria for the systematic review. In the sleep clinic population, the sensitivity was 90%, 94% and 96% to detect any OSA (AHI >/= 5), moderate-to-severe OSA (AHI >/=15), and severe OSA (AHI >/=30) respectively. The corresponding NPV was 46%, 75% and 90%. A similar trend was found in the surgical population. In the sleep clinic population, the probability of severe OSA with a STOP-Bang score of 3 was 25%. With a stepwise increase of the STOP-Bang score to 4, 5, 6 and 7/8, the probability rose proportionally to 35%, 45%, 55% and 75%, respectively. In the surgical population, the probability of severe OSA with a STOP-Bang score of 3 was 15%. With a stepwise increase of the STOP-Bang score to 4, 5, 6 and 7/8, the probability increased to 25%, 35%, 45% and 65%, respectively. CONCLUSION: This meta-analysis confirms the high performance of the STOP-Bang questionnaire in the sleep clinic and surgical population for screening of OSA. The higher the STOP-Bang score, the greater is the probability of moderate-to-severe OSA.

STOP-Bang is a self-reportable tool which includes four subjective items scored one point for yes (STOP: Snoring, Tiredness, Observed apnoea and high blood Pressure) and four demographics items (Bang: BMI, age, neck circumference, gender). The Maximum possible score is eight.

  • S—“Do you Snore loudly (louder than talking or loud enough to be heard through closed doors)?”
  • T—“Do you often feel Tired, fatigued, or sleepy during daytime?”
  • O—“Has anyone Observed you stop breathing during your sleep?”
  • P—“Do you have or are you being treated for high blood Pressure?”
  • B — BMI more than 35kg/m2?
  • A — Age over 50 years old?
  • N — Neck circumference > 16 inches (40cm)?
  • G — Gender: Male?

Results are interpreted as:

  • High risk of sleep apnoea: Score 5 to 8
  • Intermediate risk of sleep apnoea: Score 3 to 4
  • Low risk of sleep apnoea: Score 0 to 2

Obstructive sleep apnoea is a condition where the walls of the throat relax and close off the airways during sleep. This interruption to normal breathing can happen many times a night, leading to low oxygen levels in the blood and daytime sleepiness. The condition is more common in older people, males and overweight people. The symptoms typically include snoring and daytime sleepiness.

The severity of sleep apnoea is determined by how often breathing apnoea or hypopnoea episodes occur per hour, measured using the apnoea-hypopnoea index (AHI).

Severity is assessed as:

  • mild – AHI reading of 5 to 14 episodes an hour
  • moderate – AHI reading of 15 to 30 episodes an hour
  • severe – AHI reading of more than 30 episodes an hour

Expert commentary

These authors conclude that the simple STOP-Bang score is of value to detect moderate to severe sleep apnoea. Although, a limitation of the review was that the data analysed were from sleep clinic populations, which are by definition selected for a high probability of a sleep disorder, as well as surgical populations. This limits the ability to extrapolate to the utility of the questionnaire.

Improving access to the diagnosis and treatment of sleep apnoea is likely to reduce the burden of sleep apnoea on the individual and provide significant health care savings.

Mary Morrell, Professor of Sleep and Respiratory Physiology, Faculty of Medicine, National Heart and Lung Institute, Imperial College London

Expert commentary

Sleep apnoea is rising in incidence and is a significant contributor to cardio-metabolic sequelae. The STOP-Bang Questionnaire has previously been validated, but this meta-analysis draws together data from over 9000 patients, and strengthens the pretext that it provides a ready and robust method of screening for sleep apnoea. The pooled data demonstrates a stratification of likely risk with a rising total score, and adds further to its value. There is broad agreement from all the studies that this is now a tool that can be applied to a wide variety of settings, both clinical and non clinical, and is of particular value when used in pre-assessment clinics for surgical planning, especially where there is limited access to comprehensive investigations for sleep apnoea.

Peter Venn, Consultant in Sleep Medicine and Anaesthesia, Queen Victoria Hospital NHS Foundation Trust, East Grinstead