Last updated on 27th September 2017
I have already written a couple of posts on sleep apnea -"Sleep apnea - what is it, how common is it and how does it affect mortality & physical health?" and "Sleep apnea - how does it affect psychological health?". In this third & last post of the sequence, I'll explore how we can recognise sleep apnea and what we can do about it.
How is it recognized? Probably the first thing is to realise that sleep apnea is a common disorder that is important for health ... and to look out for warning signs such as weight, neck thickness, age & poor health behaviours. Interestingly an exploratory paper last year - "A pilot study of the inability to fit hands around neck as a predictor of obstructive sleep apnea" - reported that if there was "inability to place the hands around the neck with digits touching in the anterior and posterior" then "The positive predictive power (for sleep apnea) was 100% and the negative predictive power was 31.6%." However a much better validated way of screening for sleep apnea (although more time consuming) is to use a questionnaire. There are various options and, as indicated by the 2010 paper "A systematic review of screening questionnaires for obstructive sleep apnea", the STOP-BANG seems a good choice.
The STOP-BANG is an 8-item instrument - its name is an acronym for the 8 questions about Snoring, Tiredness, Observed apnea episodes, high blood Pressure, BMI, Age, Neck size, and Gender. There is an excellent website providing lots of useful information about the questionnaire. You can fill in the questionnaire itself online which helps when it comes to calculating one's BMI and, more importantly, it leads directly to an estimate of your risk of having sleep apnea. There are also numerous STOP-BANG questionnaires downloadable from the internet, including one that I put together (available as a Word doc and as a PDF file). The STOP-BANG website provides wonderful (although slightly hard to navigate) access to a wealth of research linked to the questionnaire, including sub-sections on the upper airway & perioperative medicine (both more relevant for anaesthetists), and sleep disordered breathing, STOPBang validation & STOPBang abstracts. Full text papers that are more noteworthy for "generalists" like me are this year's "STOP-Bang questionnaire: a practical approach to screen for obstructive sleep apnea", last year's systematic review "Validation of the STOP-Bang questionnaire as a screening tool for obstructive sleep apnea among different populations: a systematic review and meta-analysis" ,
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.
More to follow ...