Guidelines for Inspire Therapy Eligibility Based on AHI and BMI
For Inspire therapy eligibility, patients must have an AHI between 15-65 events/hour and a BMI less than or equal to 35 kg/m².
AHI Requirements
- Minimum AHI: 15 events/hour (moderate OSA)
- Maximum AHI: 65 events/hour (severe OSA)
- Type of events: Must be predominantly obstructive events
BMI Requirements
- Maximum BMI: 35 kg/m²
- Rationale: Higher BMI is associated with:
- Increased pharyngeal fat deposits
- Decreased upper airway patency
- Reduced effectiveness of hypoglossal nerve stimulation
Clinical Significance
The BMI restriction is critical as obesity significantly increases OSA prevalence:
- 77% OSA prevalence with BMI ~49.5 kg/m² 1
- 72% OSA prevalence with BMI ~46.1 kg/m² 1
- 48% OSA prevalence with BMI ~38.3 kg/m² 1
Research shows that patients with BMI >35 kg/m² have different obstruction patterns that may not respond optimally to hypoglossal nerve stimulation 2.
Additional Eligibility Criteria
While not part of the original question, other important criteria include:
- No complete concentric collapse at the soft palate during drug-induced sleep endoscopy
- CPAP intolerance or ineffectiveness
- Age ≥18 years
Treatment Outcomes
For eligible patients, Inspire therapy demonstrates significant improvements:
- Median AHI reduction from 28.6 to 9.5 events/hour after 12 months 2
- High therapy adherence (39.1 ± 14.9 hours per week) 2
- Significant improvements in daytime sleepiness and quality of life 2
Important Considerations
- AHI measurement: Different oximeters can affect AHI calculations by up to 3.7 events/hour 3, which may impact eligibility determination
- Sleep position: Normal BMI has a 97% negative predictive value for moderate/severe OSA in the lateral sleeping position 4
- BMI changes: Weight gain/loss can significantly affect OSA severity and individual obstruction event characteristics 5
Clinical Pearls
- Patients with BMI >35 kg/m² should focus on weight loss interventions before considering Inspire therapy
- For borderline AHI cases (near 15 or 65), consider the oximeter type used during sleep testing
- For patients using PAP therapy <6 hours nightly, consider Inspire as an alternative, as Effective AHI may remain elevated 6