The 2012 AASM Respiratory Event Criteria Increase the Incidence of Hypopneas in an Adult Sleep Center Population

Study objectives: To investigate the effect of the 2012 American Academy of Sleep Medicine (AASM) respiratory event criteria on severity and prevalence of obstructive sleep apnea (OSA) relative to previous respiratory event criteria.

Methods: A retrospective, randomized comparison was conducted in an Australian clinical sleep laboratory in a tertiary hospital. The polysomnograms (PSG) of 112 consecutive patients undertaking polysomnography (PSG) for suspected OSA were re-scored for respiratory events using either 2007 AASM recommended (AASM2007Rec), 2007 AASM alternate (AASM2007Alt), Chicago criteria (AASM1999), or 2012 AASM recommended (AASM2012) respiratory event criteria.

Results: The median AHI using AASM2012 was approximately 90% greater than the AASM2007Rec AHI, approximately 25% greater than the AASM2007Alt AHI, and approximately 15% lower than the AASM1999 AHI. These changes increased OSA diagnoses by approximately 20% and 5% for AASM2007Rec and AASM2007Alt, respectively. Minimal changes in OSA diagnoses were observed between AASM1999 and AASM2012 criteria. To achieve the same OSA prevalence as AASM2012, the threshold for previous criteria would have to shift to 2.6/h, 3.6/h, and 7.3/h for AASM2007Rec, AASM2007Alt, and AASM1999, respectively. Differences between the AASM2007Rec and AASM2012 hypopnea indices (HI) were predominantly due to the change in desaturation levels required. Alterations to respiratory event duration rules had no effect on the HI.

Conclusions: This study demonstrates that implementation of the 2012 AASM respiratory event criteria will increase the AHI in patients undergoing PSG, and more patients are likely to be diagnosed with OSA.

Commentary: A commentary on this article appears in this issue on page 1357.