0466 Consequences of Differing Hypopnea Scoring Guidelines on Mild OSA Diagnosis

Treatment of obstructive sleep apnea (OSA) improves patient symptoms and decreases the risk for various comorbid conditions. However, OSA diagnosis is complicated by multiple criteria for scoring of obstructive hypopneas. Increasingly, more stringent Medicare criteria (AHI4%) are being adopted, potentially decreasing the number of patients diagnosed and treated for OSA. Therefore, comparison to the recommended American Academy of Sleep Medicine criteria (AHI3%A) is warranted. AHI4% defines hypopnea as nasal pressure signal drop of ≥ 30% from baseline over ≥ 10 seconds with ≥ 4% oxygen desaturation. In contrast, AHI3%A requires a nasal pressure signal drop of ≥ 30% from baseline over ≥ 10 seconds, with either ≥ 3% oxygen desaturation or associated arousal. We retrospectively enrolled 121 patients diagnosed with mild OSA (5 ≤ AHI ≤ 15) by polysomnogram (PSG) using AHI3%A. Inclusion criteria included ≥ 18 years, CPAP treatment with acceptable adherence (usage ≥ 4 hours for ≥ 70% of nights), and clinical follow-up. Baseline PSGs were rescored using AHI4%. Patient charts were reviewed for changes in Epworth Sleepiness Scale (ESS). Mean AHI3%A was 10.28 ± 2.60 events/hour. When PSGs were rescored using AHI4%, a significant decrease in AHI was observed (mean AHI 4.70 ± 2.67 events/hour, p < 0.0001). Fifty-seven percent (69/121) of patients would have lost OSA diagnosis if AHI4% standards were applied. Improvement in ESS with CPAP treatment was noted in 66% of patients overall and in 61% of patients who would have lost diagnoses had AHI4% been used. The majority of our patients would have lost their OSA diagnosis had AHI4% been applied. Given the improvement in ESS in CPAP-adherent patients, this loss of OSA diagnosis would have resulted in a missed opportunity for treatment. Future work that focuses on the benefits of treating mild OSA is needed and may justify the use of AHI3%A. CTSA award UL1TR002243 from National Center for Advancing Translational Sciences