What is the recommended treatment for reducing Apnea-Hypopnea Index (AHI) according to American Academy of Sleep Medicine (AASM) and Centers for Medicare and Medicaid Services (CMS) guidelines?

AASM vs CMS Criteria for Apnea-Hypopnea Index (AHI)

The American Academy of Sleep Medicine (AASM) recommended hypopnea definition (which includes both ≥3% oxygen desaturation OR arousal) should be used for diagnosing and treating OSA as it more accurately identifies clinically significant respiratory events compared to the CMS criteria (which requires ≥4% desaturation only).

Key Differences Between AASM and CMS Criteria

AASM Recommended Criteria:

• Scores a hypopnea when there is:
  • ≥30% drop in airflow from baseline
  • Duration ≥10 seconds
  • Associated with EITHER ≥3% oxygen desaturation OR an arousal 1

CMS Criteria (Medicare):

• Scores a hypopnea when there is:
  • ≥30% drop in airflow from baseline
  • Duration ≥10 seconds
  • Associated with ≥4% oxygen desaturation ONLY 1

Clinical Impact of Different Scoring Criteria

Effect on AHI Values

• Using the CMS criteria (≥4% desaturation only) results in significantly lower AHI values:
  • Up to 70% lower AHI compared to criteria that include arousals 1
  • In one study, 48% of patients diagnosed with OSA using arousal-based criteria would be classified as negative using the CMS criteria with an AHI cutoff of 30/h 1

Patient Implications

• Patients with clinically significant OSA may be missed if arousal-based events are not counted:
  • Particularly affects lean patients who may have significant hypopneas with minimal desaturation 1
  • 40% of symptomatic patients with OSA could be misclassified as normal when using the CMS criteria 1

AASM Position Statement

The AASM has issued a clear position statement that:

1. The RECOMMENDED scoring criteria for hypopneas (including both ≥3% desaturation OR arousal) should be used in clinical evaluation of patients with suspected OSA 1

2. Even when centers must use the CMS criteria for reimbursement purposes, they should still capture arousal-based events by either:

   • Scoring hypopneas using the AASM recommended criteria
   • Reporting the Respiratory Disturbance Index (RDI) which includes RERAs (Respiratory Effort Related Arousals) 1

3. Not including arousal-based events may lead to:

   • Lack of proper diagnosis
   • Misclassification of OSA severity
   • Misidentification of other sleep disorders 1

Treatment Implications

Treatment Decisions

• For patients with an AHI ≥20 events/h, PAP therapy is recommended regardless of symptoms 1
• For those with an AHI 5-20 events/h, treatment decisions should consider:
  • Presence of excessive daytime sleepiness
  • History of sleepiness-related crashes
  • Severity of desaturation
  • Presence of comorbidities 1

Treatment Effectiveness

• Treatment targets should aim to reduce AHI to <5 events/hour 2
• Even with optimal CPAP therapy, treatment effectiveness depends on adherence:
  • Patients using CPAP ≥6 hours typically achieve an Effective AHI <5 3
  • Patients using CPAP <6 hours may still have moderate-to-severe OSA during non-CPAP time 3

Practical Considerations

Home Sleep Testing Limitations

• Most home sleep testing devices cannot detect arousals due to absence of EEG data
• This makes the AASM recommended criteria difficult to apply with home testing 1
• An in-laboratory PSG should be performed when home sleep apnea testing results are negative in patients with high clinical suspicion for OSA 1

Technical Factors

• Choice of oximeter can significantly affect AHI values:
  • Different oximeters with varying signal averaging times can change whether a patient meets treatment criteria 4
  • In one study, 7 of 35 patients were reclassified as meeting or not meeting Medicare criteria based solely on which oximeter was used 4

Bottom Line

For clinical decision-making regarding OSA diagnosis and treatment, the AASM recommended criteria that include both oxygen desaturation and arousals provide a more comprehensive assessment of sleep-disordered breathing and should be used to guide treatment decisions. The CMS criteria may underdiagnose clinically significant OSA, particularly in lean patients and those with arousal-based respiratory events.