Patient compliance the key to treating OSA

Obstructive Sleep Apnoea (OSA) syndrome is a very common disorder, affecting approximately 4% of men and 2% of women in the middle-aged workforce. The hallmark repetitive narrowing of the pharynx during sleep and consequent sleep fragmentation and oxygen desaturation, lead to numerous short and long term sequelae.

The immediate effects of this disorder are excessive daytime sleepiness and deficits in neurocognitive performance, both of which directly impact on quality of life as well as having implications for safety (e.g. driving). In the longer term, there is growing evidence that untreated OSA increases the risk of cardiovascular morbidity and mortality, through conditions such as hypertension, myocardial infarction, and stroke.

More recently, with an emerging epidemic of obesity and diabetes, potentially important links to OSA are receiving attention. The high prevalence and significant health consequences of the disorder give rise to a major public health problem, and the financial burden of OSA and related sleep disorders has been recognised.

Lifestyle changes, such as weight loss, avoidance of alcohol and positional changes in bed may assist in the treatment of snoring, although OSA is more difficult to treat in this manner. The standard treatment - continuous positive airway pressure (CPAP) - has been demonstrated to provide major clinical benefit to patients with OSA. In particular, clinical trials have identified a significant reduction in daytime sleepiness, improvement in neurocognitive performance and quality of life, and small but clinically important reductions in blood pressure. Longer-term benefits on cardiovascular risk factors remain to be shown. These benefits are most evident in patients with more severe forms of the disorder.

In milder disease, it seems that the benefits of alleviating OSA are offset by the obtrusive nature of CPAP therapy. Hence, whilst CPAP it is an extremely efficacious treatment in patients who use it, its effectiveness in the clinical setting is hampered by low rates of compliance. This is largely related to difficulties with tolerance and side-effects. Research studies indicate that patients who continue to use CPAP average only 4-5 hours per night, on approximately 70% of nights, which is unlikely to be sufficient to optimise clinical benefit. More problematical is that large, but unspecified, numbers are known to have abandoned CPAP treatment altogether. Consequently, there are concerns that as many as half of mild to moderate OSA patients may no longer be receiving appropriate treatment.

These difficulties with CPAP therapy have initiated a search for simpler and effective treatment alternatives. An important alternative is oral appliance therapy, usually in the form of mandibular advancement splints (MAS). The growing enthusiasm for their use in clinical practice is supported by research evidence showing that such treatment can be used to effectively manage a substantial number of OSA patients, particularly with mild to moderate OSA.

Beyond improvements in symptoms such as snoring, witnessed apnoeas and daytime sleepiness, early studies have identified a positive effect on blood pressure and aspects of neurocognitive performance, similar to that seen with CPAP therapy. Recently updated practice parameters from the American Academy of Sleep Medicine recognise the important role of this treatment and endorse MAS devices as an alternative treatment to CPAP.

A number of rigorous clinical studies have directly compared MAS and CPAP, and whilst CPAP is more efficacious at reducing sleep-disordered breathing, the health benefits of the respective treatments appear to be similar. Importantly, oral appliances tend to be preferred by patients, and this has potentially important implications for treatment compliance and long term health benefits.