Sleep testing (polysomnography or PSG) to diagnosis obstructive sleep apnea (OSA) is expensive and inconvenient, and may not be easily available to patients in rural or under-resourced settings. Is there another option? A new study is reporting a simple, practical approach for primary care diagnosis of OSA. It involves four questions and a simple, inexpensive test.
The researchers identified 4 independent predictors of OSA and assigned each one a point value:
- the patient’s snoring has bothered other people (3 points),
- A waist circumference greater than 102 cm in men or greater than 88 cm in women (3 points),
- Being older than 50 years (2 points), and
- Someone has noticed that the patient stops breathing during sleep (2 points).
The total score has 10 points, and a positive screening result was 5 or more points. This clinical rule was 100% sensitive in the development group.
The other part of the screen was an ApneaLink monitor, a simple test to measure blood oxygen via a finger monitor at night. This test had good accuracy using at least 3% oxygen desaturation as the cutoff for an abnormal result.
With the goal of minimizing the need for PSG, the researchers proposed a 2-stage diagnostic model:
- Patients with a score of 5 or higher on the clinical rule would use the home ApneaLink monitor,
- Those with at least 3% oxygen desaturation would be given the diagnosis of sleep apnea.
This approach was tested prospectively on a validation group, and it had excellent negative predictive value (96% – ability to rule out those who do not have OSA) and moderately good positive predictive value (56% — the ability to predict OSA).
So, here’s how I’ll use the information in our clinic for uninsured patients:
- For patients with a score of 5 or higher on the clinical rule, I’ll order a home ApneaLink monitor (or similar test that evaluates blood oxygen levels for one night),
- Those with at least 3% oxygen desaturation will be given the diagnosis of sleep apnea.
- For those with a score of 5 or higher and a desaturation of less than 3%, I’ll have to try to arrange a PSG test to be sure that they do not have OSA.
It will be interesting to see if other researchers can replicate this, but for those of us seeing patitents without insurance, this has the potential to be great news.