Bajaj N, Johnsen J , Ghosh K and Auerbach SH
Objectives: Due to change in AASM recommended scoring criteria in 2012, we observed that many patients are diagnosed to have moderate-severe OSA and may not need CPAP therapy. We compared AHI derived using AASM recommended scoring definitions in 2007 (AHI2007) and 2012 (AHI2012). We also assessed its impact on prevalence of OSA diagnosis and suggest new OSA classification.
Methods: Retrospective review of 290 consecutive patients who underwent in-lab PSG in a tertiary care hospital during a 3 month period. For AHI2007, hypopneas were required to have ≥ 30% airflow reduction and ≥ 4% desaturation; and for AHI2012, hypopneas were required to have ≥ 30% airflow reduction and ≥ 3% desaturation or arousals.
Results: Frequency of mild, moderate and severe OSA were 27.6%17.9% 23% vs 23.1%, 22.8%,39.7% using AHI2007 and AHI2012 respectively. This resulted in increased prevalence from 68.6 to 85.5%, diagnosing moderate-severe OSA in 62.5% vs 41% and labeling 21.5% with absent or mild OSA as having moderatesevere disease. An equivalent cut-point of 10, 20, 40 events/hour was explored for AASM 2012 instead of 5, 15, 30 events/hour. Using the new cut-points, prevalence was 71% (vs 85% AHI2012), moderate-severe OSA 45% (vs 62% AHI2012), severe OSA 26% (vs 40% AHI2012) almost comparable to 68.6%, 41% and 23% respectively from AASM 2007.
Conclusions: Most studies on OSA used the old scoring and significant associated risks were present in moderate-severe disease. This study demonstrates using AASM 2012, overall prevalence increased and a significant percentage of patients with absent or mild OSA were labeled in higher risks category. This translates to unnecessary CPAP treatment and higher healthcare costs with no significant health benefits for this “false positive” cohort. We suggest consideration to be given to a new cut-point for classification of OSA using AASM 2012.
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