This blog post discusses an article in the February 2013 issue of the medical journal Otolaryngology—Head and Neck Surgery.

Patients with obstructive sleep apnea are often treated solely based on a result from their sleep study: the apnea-hypopnea index (AHI), the number of episodes of blockage of breathing per hour of sleep.  The AHI is extremely important, but it only captures part of why patients are treated for snoring or sleep apnea.  A previous blog post discussed the importance of looking beyond the results of sleep studies, such as the AHI.  Basically, patients may need treatment because of their snoring that disturbs others, the potential health implications of sleep apnea, and the disruption of sleep that can lead to unrefreshing sleep and sleepiness or fatigue during the day.

Although the health effects of sleep apnea are loosely related to the AHI, Dr. Edward Weaver and his team at the University of Washington have performed a number of studies showing that there is no relationship between AHI and symptoms such as sleepiness and quality of life.  This month’s article extends the analysis to a measure, called the Sleep Apnea Severity Index (SASI), was developed by Dr. Jay Piccirillo at Washington University in St. Louis and colleagues from other institutions.  The SASI combines results from a sleep study (including the AHI) with findings from physical examination and sleepiness in a broader assessment of sleep apnea severity than is possible with the AHI alone.  The study published this month showed that, across a group of more than 200 patients, the SASI was more closely associated with sleep study results and other measures of symptoms than other, more-limited assessments (including the AHI by itself).  There is a saying of “Don’t miss the forest for the trees”.  In this case, focusing on the AHI misses the bigger picture for patients and the impact of sleep apnea on their lives.

Overall, this article reinforces the importance of considering patients as individuals rather than with a single number like the AHI.  A broader assessment, whether or not the SASI or measures like it, is critical for making snoring and sleep apnea treatment decisions, including for surgery.  In my lectures and discussions with sleep physicians (surgeons and non-surgeons) and sleep dentists in the United States and around the world, it is clear that there is too much focus on the AHI alone when treating obstructive sleep apnea.  This was the basis for our coming together to develop a framework for reporting the results of sleep apnea surgery trials, and a similar approach should be adopted for nonsurgical treatments, such as CPAP and oral appliances.

2 Responses to “Obstructive Sleep Apnea Is More Than Just AHI”

  1. Deborah Wardly, MD

    yes, I absolutely agree. but there is still more to look at than just symptoms/SASI and the AHI. Chervin and colleagues showed recently that disruptive behavior disorders correlated with esophageal manometry results but not with the AHI. the esophageal pressures also predicted improvement in behavior after treatment, while the AHI did not. an earlier study by the same group showed neurocognitive improvement in ADHD patients after adenotonsillectomy who had NOT been diagnosed with OSA by the AHI, suggesting that a different and more sensitive measure of SDB on the sleep study may be required for detecting mild SDB.
    Dr. Deb

    Reply

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