Obstructive Sleep Apnea (OSA) is defined as RDI/AHI>5/hr with symptoms or RDI/AHI>15/hr without symptoms. Apnea Hypopnea Index (AHI) is defined as number of apneas plus Hypopneas divided by total sleep time (TST). There are different hypopnea definitions published at different timelines-

SourceYearCriteria
AASM Task Force (Chicago Criteria)1999Either ≥ 50% airflow reduction OR a lesser airflow reduction with associated ≥ 3% desaturation or arousal
AASM Scoring Manual 2007Recommended or IA: ≥ 30% airflow reduction and ≥ 4% desaturation 
Alternate or IB: ≥ 50% airflow reduction and ≥ 3% desaturation
AASM Scoring Manual 2012Recommended or IA: ≥ 30% airflow reduction and ≥ 3% desaturation or arousal 
Acceptable or IB: ≥ 30% airflow reduction and ≥ 4% desaturation 

American Academy of Sleep Medicine (AASM) currently recommends 2012 IA hypopnea definition whereas insurance recommends 2012 IB hypopnea definition. These different recommendations regarding hypopnea definition should not be the case and professional bodies should agree on one definition of hypopnea based on scientific evidence.

I think we should use 2012 IA definition for scoring Hypopneas based on following scientific evidence-

  1. 2012 IA hypopnea definition diagnose more women with OSA as compared to 2012 IB definition. (J Clin Sleep Med. 2024 Nov 20.)
  2. Use of the 2012 IB definition resulted in the failure to identify a significant number of individuals with OSA who eventually developed hypertension (J Clin Sleep Med. 2020 Oct 15;16(10):1753-1760)
  3. Less no. of young pts were eligible for OSA treatment with 2012 IB definition (Sleep Breath. 2016 Dec;20(4):1169-1174)
  4. 2012 IA hypopnea definition leads to more Diagnosis of Mild OSA (J Clin Sleep Med. 2018;14(12):1987–1994. )
  5. Use of 2012 IA hypopnea definition to define Mild OSA was associated with higher odds of developing HT in Mild OSA (J Clin Sleep Med. 2019;15(9):1261–1270. )

I also feel that in countries where insurance is not paying for sleep studies and PAP devices, we should formulate clear guidelines to use only one hypopnea definition which should be 2012 IA hypopnea definition.