Open Access
Feature Article

Obstructive sleep apnoea – navigating the system

Open Access
Feature Article

Obstructive sleep apnoea – navigating the system

CLAIRE M. ELLENDER, CERYS JONES, CRAIG HUKINS

Figures

© chameleonsey/ istockphoto.com Models used for illustrative purposes only
© chameleonsey/ istockphoto.com Models used for illustrative purposes only
Dr Ellender is a Respiratory and Sleep Physician at the Princess Alexandra Hospital, Metro South Hospital and Health Service, Brisbane; and Senior Lecturer at the Faculty of Medicine, Princess Alexandra Southside Clinical Unit, University of Queensland, Brisbane. Dr Jones is a General Practitioner at Eastbound Medical Clinic, Bentleigh East, Melbourne, Vic. Dr Hukins is a Respiratory and Sleep Physician at the Princess Alexandra Hospital, Metro South Hospital and Health Service, Brisbane; and Associate Professor at the Faculty of Medicine, Princess Alexandra Southside Clinical Unit, University of Queensland, Brisbane, Qld.

Additionally, severe OSA is associated with a 25% increased relative risk for developing cancer, controlling for confounders.5 

Epidemiology

Across all populations, at least 14% of men and 5% of women will have some of sort of OSA.6,7 OSA has been increasing in prevalence in recent years.8

Data from the Bettering the Evaluation and Care of Health (BEACH) program has shown that sleep disturbance is within the top 30 reasons for attendance in general practice.9 

Risk factors

The common risk factors for OSA are age greater than 65 years, obesity, male sex and anatomical features such as retrognathia.3 Obese adults (body mass index [BMI] greater than 30 kg/m2) have as high as a 45% risk of OSA, compared with a 25% risk in those who are overweight (BMI 25 to 29.9 kg/m2).10 There is a strong association between OSA and other chronic diseases such as heart failure and end-stage kidney disease.

Advertisement

Presenting features and their assessment

The key presenting features of OSA are listed in Box 1. A history of excessive daytime sleepiness and nocturnal choking or gasping is the most predictive for a diagnosis of OSA. Although some patients will present with nocturnal symptoms of snoring, a history of nonrestorative sleep, morning headaches and need for an afternoon nap can also point to this diagnosis. 

The most widely validated self-report tool to quantify excessive daytime sleepiness is the Epworth Sleepiness Scale.11 The scale is a summation of eight items, with a score above nine considered higher than normal daytime sleepiness and greater than 16 suggestive of severe excessive daytime sleepiness. The STOP-BANG, OSA-50 and Berlin questionnaires are validated screening tools for sleep apnoea.12-14 Significant results with these tools are a score of 3 or higher for the STOP-BANG questionnaire, a score of 5 or higher for the OSA-50 questionnaire and a ‘high risk’ result for the Berlin questionnaire.

An approach to the primary care investigation and treatment of a patient with OSA is shown in the Flowchart.

Advertisement

Investigating patients suspected to have OSA

In a patient with symptoms suggestive of OSA, a sleep study (polysomnogram) is needed to make a formal diagnosis. A sleep study involves measurement of electroencephalography (EEG) to confirm sleep stage, as well as measurement of chest and abdominal wall movement, nasal airflow and pressure, in addition to oxygen saturation, ECG and leg movements. Using data from the sleep study, OSA is categorised as mild, moderate or severe disease, based on the number of obstructive events per hour, known as the apnoea-hypopnoea index (AHI). An AHI of five to 14 events per hour indicates mild OSA, an AHI of 15 to 29 indicates moderate OSA and an AHI of greater than 29 indicates severe OSA.

A Medicare subsidy is available for GP referral of patients for overnight sleep studies to confirm the diagnosis of OSA, providing certain criteria are met (Box 2).

At-home sleep studies versus in-laboratory sleep studies 

Most patients being investigated for OSA will be suitable for an unattended ‘type 2’ home-based sleep study (sometime also referred to as a ‘level 2 study’). Home-based studies can be used to confirm the diagnosis of OSA in patients with a highly suspicious history. However, because of the reduced data-set compared with laboratory testing, home sleep studies are not usually appropriate for investigating other sleep disorders, such as parasomnia, narcolepsy, nocturnal seizures or suspected hypoventilation disorders.

Advertisement