Published in SLEEP MATTERS – APRIL 2020 Edition- by the Sleep Apnoea Trust

There is a dilemma in the UK; there are no accurately researched and peer reviewed estimates of the numbers of people with obstructive sleep apnoea, diagnosed or undiagnosed.

This article is not to undermine or criticise those who have attempted to quantify the situation; it is based on our position as a patient support charity, constantly getting feedback from its members and dealing with the many Sleep Clinics throughout the UK. We also gain from one of our members being on the current NICE Guideline Committee and benefitting from the intense scrutiny of all published information related to sleep apnoea and its related afflictions.

Data measurement on anything to do with sleep apnoea is difficult to find, but the following is a record of respiratory sleep tests in England from NHS data between 2006 to 20191. During this period 1.45 million diagnostic sleep tests were completed in England. The data from Northern Ireland, Scotland and Wales has to be estimated, bringing that figure up to 1.8 million. Add to that the estimated 200,000 for those tested before 2006 and that brings the final figure up to 2 million tested.  It is then estimated that 50% of the sleep tests generate a CPAP prescription, and therefore 1 million people have been prescribed CPAP since treatment started in the UK in the early 1990s.

However, around 30% of those prescribed do not continue with their therapy2, so at present, there are approximately 700,000 people in the UK successfully established on CPAP.

As you can see, there are several estimates, but at least factual data is the starting point

When it comes to assessing how many of the UK population suffer from sleep apnoea, sadly, the starting point is based on an assessment in 1993 on a group of 603 people between 30 and 60 named the Wisconsin Sleep Cohort Study. The figures used for many years of 4% of middle-aged men and 2% of middle aged women were derived from a 1993 American research paper3.

NICE in TA139 March 20084, which mandated CPAP therapy free on the NHS for moderate and severe OSA confirmed these figures, so there was no question about their accuracy, despite being 15 years out of date and applying to a small group of people in America.

However, lurking in the background was the obesity crisis, with almost double figure rises in obesity. Almost no notice of its effect was detected despite the UK population putting on excessive weight for many years.

5% of the general population with OSAHS (OSA with symptoms) was confirmed as a general estimate across Europe in the 2013 EU Working Group study in driving and OSA5.

While recognising that obesity was the main driver of the increased prevalence, it was only studies on the data from the USA that showed evidence of the effect of the emerging obesity epidemic.

The excellent BLF (British Lung Foundation) study in 20146 estimated 1.5 million adults with 330,000 diagnosed and this report did warn about increasing obesity rates.

At this point we need to illustrate that the increasing levels of human weight have become the main causal effect of the increase in the UK.

Between 1993 and 2018, adult obesity and overweight levels had risen from 53% to 64% of the adult population7.Even worse, within those figures, obesity had doubled from 15% to 30%. One in every three people in the UK today is obese!

Reality hit SATA in June 2017, when, during a debate about anaesthetics at the CARE Convention in Warwick University, a leading anaesthetist stated that his hospital has introduced a screening policy, not based on the out of date 4% and 2%, but from their experience of it being three times those numbers. His justification was a research paper published by Dr Peppard et al in 2013, “Increased prevalence of Sleep Disordered Breathing (SDB) in Adults”8 in which he identified that between the ages of 30 and 70, 13% of men and 6% of women had moderate or severe OSA.

The data came from the same source as the 1993 figures, the Wisconsin Sleep Cohort Study in the USA as it existed in 2011!

These figures were confirmed by another paper from the UK and Ireland, “Epidemiological aspects of obstructive sleep apnoea” by Garvey et al.9

It was a shock for SATA and most people at the conference, but also a wake-up call. The SATA Committee discussed the implication of these results for the UK with our medical advisors. The obesity crisis in the UK is 10 years behind the reality in the USA from 2010. It also confirmed reports we were getting that waiting times for sleep tests were growing at many Sleep Clinics, but as always, it is widely variable across the UK.

We immediately changed our figures to these new percentages, but also added in an estimate that extended the age cover from 30 to 75 rather than 70 (as people are living longer) and using the term “up to 13% of adult men” and “up to 6% of adult women” to make some allowance for variations.

The figures surprised us as they resulted in a total of up to 3.9 million people in the UK who had moderate or severe OSA, well over double any previous estimates. We published them in the Chairman’s Report at the SATAday 2017 Conference and updated our website. They have never been challenged!

SATA has reviewed more data than can possibly be comprehended and it is clear that the current estimate in the 2018 Nice SDB Scoping Document10 of 2.5 million with undiagnosed OSAHS is closer to reality but still underestimating what is a rapidly developing situation linked directly to the obesity epidemic. We challenged that figure in the 2018 NICE Consultation11 and do so again now, as it is not sufficiently factoring in the rising obesity levels.

Today, on the factual data currently available in England, 29% of adults are obese and 35% are overweight. In simple terms 2 out of every 3 adults have a BMI greater than 25kg/m2 (Parliamentary Briefing Paper No 3336, Aug 2019)7. According to the NHS, 67% of men and 61% of women are overweight and obese in England alone; this trend will continue for some time.12

Therefore SATA is sticking with its figures and has updated them taking into account the latest available population figures.

We now estimate that:

  • up to 4 million people have moderate or severe OSAS (OSA with symptoms such as excessive sleepiness during waking hours)
  • up to 6 million people have mild OSA, some with excessive sleepiness (Peppard 2013 8)
  • therefore up to 10 million people have Obstructive Sleep Apnoea, some with the most common symptom of excessive sleepiness during waking hours
  • we estimate that 700,000 people out of the 1 million diagnosed are currently using CPAP regularly.

The NHS works on big numbers to plan its resources to keep us all healthy and well treated. In order to plan the staff, facilities and budgets to support sleep apnoea patients, like any business, someone, somewhere has to estimate what the market is and what it will be in coming years.

The obesity epidemic is the biggest threat to public health in the UK.

The USA figures are from 2011 and with the 10 year lag, we may hit these levels in 2021 – NEXT YEAR!

The difference between NICE’s current undiagnosed 2.5 million OSAS, when added to the 1 million prescribed CPAP making 3.5 million and SATA’s up to 4 million moderate and severe is not so wide.

In terms of costs, the answer is simple. An undiagnosed patient with moderate or severe OSA will cost the NHS twice that of a patient diagnosed and treated with CPAP. Using the BLF 20146 cost estimates it reckoned 80% of 1.5 million were undiagnosed and this was costing the NHS £28 million a year. Based on this, then, with 3 million still to diagnose, the current cost to the NHS is £96 million.

With mild OSA coming in at 6 million, based on Peppard’s 2013 figures8, of whom a number will have symptoms, it is time for the NHS to plan to deal with a much higher level of sleep apnoea patients. Treating them will, as NICE TA139 proved conclusively, save money, by preventing the development of expensive comorbidities

We take comfort that, with the new NICE Guideline due later this year, the NHS is getting ahead of the game and this will help all those engaged in resourcing what is required to meet the ever increasing demand.


2Identifying poor compliance with CPAP in obstructive sleep apnoea: DipansuGhoshaVictoriaAllgarb

3The occurrence of sleep-disordered breathing among middle-aged adults. Young  DOI:10.1056/NEJM199304293281704


5 “New Standards and Guidelines for Drivers with Obstructive Sleep Apnoea Syndrome”  EU working group 2013



8 Increased prevalence of Sleep Disordered Breathing (SDB) in Adults-Peppard 2013 DOI:10.1093/aje/kws342

9 “Epidemiological aspects of obstructive sleep apnoea” by Garvey et al (DOI: 10.3978? j.issn.2072-1439.2015.04.52).




“Obstructive sleep apnoea and comorbidities: a dangerous liaison”

A review of a review!

We have all been there. Our Sleep Apnoea has finally been diagnosed, we have got a CPAP machine and are ready to start treatment. All of us will have heard our sleep doctors and nurses advise us about the increased risk of things like heart disease or stroke associated with our condition but, in reality, it is lack of sleep that is the overwhelming problem and the thing that we really want to be sorted out.

But what about those other conditions? Can those really be associated with OSA? Is there anything else that could be associated with or made worse by our condition?

The answer is “yes”!

Will CPAP help with those problems as well?

The answer is less clear – “yes in some cases, maybe in others”!

In fact, the association of OSA with a range of conditions (co-morbidities) including heart and blood pressure problems (cardiovascular disease), stroke (cerebrovascular disease) and conditions like diabetes (metabolic diseases) was recognized many years ago but what has not been clear has been whether OSA is a result of these conditions or at least associated with them, or if it is actually the cause (or at least one of the causes). There have always been problems in confirming which of these is true.

A recent review has attempted to shed light on some of these problems and has identified many of the risks associated with untreated OSA. Entitled “Obstructive Sleep Apnea and Comorbidities: a dangerous liaison” the review appeared earlier this year in the journal Multidisciplinary Respiratory Medicine” (the full title and authorships are given at the end of this article). A great deal of work has been done in recent years on these co-morbidities and this review draws together the results of the most important of these studies on the most common and/or important of the possible co-morbidities.

To quote directly from the review: “Several recent studies reported that such co-morbidities occur commonly in OSA patients. The distribution of co-morbidities differed between men and women, with diabetes and ischemic heart disease (disease caused by poor blood supply) being more prevalent in men with OSA, and high blood pressure (hypertension) and depression being more prevalent in women with OSA compared to non-OSA subjects”. The authors note that “according to some studies, the co-morbidity burden progressively increases with OSA severity”.

These co-morbidities are themselves all complex conditions and it can be very difficult to determine what is causing what! In addition, the many different studies on these factors have different focuses with OSA being the centre of only some. This means that it can be difficult to make direct comparisons between them. Taken together these may cloud the identification of the role of OSA or of CPAP treatment.

Effects of CPAP treatment

Many of the studies on co-morbidities in OSA patients included in the review did examine the effects of CPAP treatment. Different studies showed different results but overall, they seem to show that the occurrence of co-morbidities in OSA patients could identify subgroups of patients at high risk, who might benefit from CPAP treatment. Several studies have tried to determine whether there are differing clinical characteristics of patients with OSA (compared to those who do not have the condition) and of different types of patient within the OSA group. For example, a cluster of patients with few OSA symptoms but a high co-morbidity burden has been reported by most studies published so far; such a cluster at least partly overlaps with the cluster of elderly OSA patients. Recent analyses pointed to disturbed sleep and hypoxia (reduced oxygen supply) as risk factors for cardiovascular events or death, and regular CPAP use appeared to exert a protective effect.

Cardiovascular and cerebrovascular diseases

Systemic hypertension

This condition is high blood pressure in the vessels that carry blood from the heart to the body’s tissues and is the blood pressure that is measured in your doctor’s surgery. The reviewers note that this condition has been the most studied co-morbidity in OSA. They point out that a positive relationship has been shown between OSA severity and blood pressure and that resistant hypertension (poor control of blood pressure by three antihypertensive drugs) is frequent in OSA patients. Analyses of several studies showed that, on average, blood pressure decreased by only a small amount during CPAP treatment, but the effect varied according to OSA severity, compliance with CPAP treatment and baseline blood pressure values. The reviewers state that, in general, treatment of blood pressure with drugs is necessary in hypertensive OSA patients, because CPAP alone is not enough.

Cardiovascular events and/or death.

The reviewers examined several studies that addressed the question of OSA and cardiovascular disease and death. They noted differences between the results of different studies, mainly depending on whether the studies were purely observational and dealt with all types of patient with OSA, or if they involved specially designed trials of treatments for patients with a known high cardiovascular risk. The former type of study confirmed the general association of untreated OSA with overall and cardiovascular mortality and that the raised risk of this type of disease in patients with severe OSA could be reduced by CPAP treatment. However, more targeted studies on the effects of CPAP in patients with known coronary or cerebrovascular disease (stroke etc.) failed to show any protective effect of CPAP treatment.

The authors of the review suggest that the selection of patients with different characteristics in the different types of study might explain the different results.


They also note that “Good compliance to CPAP (i.e. average nightly use of at least four hours) was associated with some protection, especially for occurrence of stroke”. Several of the studies reviewed reported an increased risk of stroke in snorers and OSA patients, but the reviewers note that the role of CPAP treatment in reducing strokes and in recovery from strokes is not clear. While CPAP treatment “may reduce the risk of stroke” they consider that “more studies are necessary to evaluate the possible protective effects of CPAP on survival after stroke”.


Arrhythmias (irregular heartbeats) are frequent in OSA patients, especially atrial fibrillation (the most common serious abnormal heart rhythm) and CPAP treatment is reported to have a protective effect in this condition. However, its protective effects on ventricular arrhythmias (less common but much more serious) are less clear.

Metabolic diseases

Metabolic syndrome & Diabetes

The relationship between OSA and metabolism (the chemical reactions in the body) is complex and the subject of much research, particularly with the world-wide epidemic of obesity (with which OSA is often associated) and the increasing occurrence of type 2 diabetes.  The review authors note that metabolic syndrome, a pre-diabetic state associated with central obesity (abdominal obesity) and increased cardiovascular risk, is very common in OSA patients.  OSA may play a role in the development of insulin resistance (a pre-diabetic state) through intermittent hypoxia (oxygen shortage in the tissues) and sleep loss or fragmentation. Short-term CPAP treatment for 8 hours per night improves insulin resistance, so prolonged nightly treatment with CPAP may be needed to modify the way our bodies deal with glucose (and hence reduce the risks of diabetes) in OSA.

Data on the effects of CPAP on the complications of diabetes are scarce but the reviewers suggest that treatment of OSA may help to prevent severe consequences. This is because untreated OSA in diabetic patients is associated with an increased occurrence of several potentially serious conditions including neuropathy (nerve damage), peripheral arterial disease (narrowing of vessels other than those which supply the heart and brain), diabetic retinopathy (damage to the retina of the eye) and diabetic nephropathy (kidney disease). They summarise their review of the literature on this topic by stating that “OSA may worsen metabolic abnormalities, and regular and effective OSA treatment could play a protective role, especially when people make lifestyle changes and actively lose weight. Screening for OSA in diabetic patients should be systematically done, since CPAP treatment for at least four hours each night may be protective, especially when diabetic complications are also present”.

Kidney diseases

Kidney diseases and OSA share common risk factors, like high blood pressure, diabetes, obesity and advanced age. Each of these factors may contribute to the onset and progression of the others. Although studies have not consistently reported an association between OSA and alterations in kidney function, some studies have suggested that reduced kidney function and chronic kidney disease is more common among patients with OSA. Most papers on the effects of OSA treatment on kidney function showed positive effects of CPAP. In summary, there is some evidence that OSA may worsen kidney function, and CPAP may exert beneficial effects.

Respiratory problems

Chronic Obstructive Pulmonary Disease (COPD)

OSA affects breathing and one might expect a relationship between the condition and lung disease. The authors of the review point out that both OSA and COPD are common conditions and may occur in the same patient. If they do, their association is known as “overlap syndrome”. In OSA patients, occurrence of the overlap syndrome increases with age, unsurprising as COPD is more common in older subjects. Recent observational studies have reported increased mortality in overlap patients compared to OSA patients without COPD, and a protective effect of CPAP treatment. The review authors state that they consider that better understanding the details of the condition of individual patients with overlap syndrome is needed to optimize treatment of both diseases.


The reviewers examined possible interactions between OSA and asthma, noting that these common conditions are often associated. OSA symptoms frequently occur in asthmatic patients who also report daytime sleepiness, poor asthma control and reduced quality of life. They reported that much of the available literature shows that OSA is more common in asthmatics than in individuals without asthma and that OSA often leads to a worsening of the condition.

Analysis of the published material showed that mild to moderate OSA occurred in 49% of patients with difficult-to-treat asthma, and that patients with severe asthma frequently showed an increased severity of OSA, poor sleep quality and daytime sleepiness. In patients with suspected or confirmed OSA, some studies highlighted the association of asthma and obesity, especially in women. However, the overall situation is far from clear, as some studies have shown a positive relationship between severity of OSA and severity of asthma symptoms while others have not.  Further studies are needed to clarify the relationship between these two conditions, and to assess whether CPAP treatment could be a useful part of asthma treatment in OSA patients, especially in cases of poorly controlled asthma.


Numbers of studies have been undertaken in recent years to determine if there is any association between OSA and cancer. Once again, the reviewers note that the situation not clear. Some studies reported increased incidence of cancer in groups of OSA patients; others did not. Their conclusion is that, although most studies indicate OSA may increase cancer risk, firm evidence is lacking, and further studies are required.


In their conclusions the authors point out that co-morbidities are common in OSA patients, and OSA can potentially lead to worse outcomes of these conditions “justifying the hypothesis of a dangerous liaison between OSA and co-morbidities”. Interestingly they also conclude that “although the possible protective role of OSA treatment is still uncertain, it could differ among different clinical types of OSA patients”.

They consider that although personalized medicine is slowly developing in the OSA field, there is a need to determine the best treatment for different individuals.  In particular, they draw attention to the need to consider the role of co-morbidities in elderly OSA patients and in women with OSA, given the differences in disturbances to normal body function and the symptoms displayed that are shown by members of these two groups, as compared to those shown by middle-aged men who have been studied most commonly so far. They end by stating that they consider that careful assessment of co-morbidities should become standard clinical practice for OSA patients.


Bonsignore MR., Baiamonte P., Mazzuca E., Castrogiovanni A. and Marrone O. Obstructive sleep apnea and comorbidities: a dangerous liaison. Multidisciplinary Respiratory Medicine (2019) 14:8.