By what percentage is a home sleep study more likely to underestimate the severity of sleep apnea?

Home Sleep Studies Underestimate Sleep Apnea Severity by 10-26%

Home sleep apnea tests (HSATs) typically underestimate the severity of obstructive sleep apnea (OSA) by approximately 10-26% compared to in-laboratory polysomnography (PSG). 1, 2, 3

Why Home Sleep Studies Underestimate OSA Severity

Technical Limitations

• HSATs lack electroencephalography (EEG), electrooculography (EOG), and electromyography (EMG) sensors, which are required to accurately determine sleep versus wake states 1
• Without sleep staging capability, HSATs calculate respiratory events based on total recording time rather than actual sleep time, leading to underestimation of severity 2
• HSATs are unable to detect hypopneas that are only associated with cortical arousals, further contributing to underestimation 1

Specific Underestimation Patterns

• In a retrospective analysis of 838 diagnostic PSGs, 26.4% of patients with OSA would be reclassified as having less severe or no OSA when recalculating the apnea-hypopnea index (AHI) using time in bed rather than total sleep time 2
• Of patients with mild OSA (AHI 5-15), 18.5% would be reclassified as not having OSA when using HSAT parameters 2
• For moderate OSA (AHI 15-30), 40.3% would be downgraded to mild OSA 2
• For severe OSA (AHI ≥30), 36% would be reclassified as moderate 2

Meta-Analysis Evidence

• A meta-analysis found that respiratory disturbance index (RDI) values on portable sleep studies were on average 10% lower compared to laboratory studies (odds ratio 0.90; 95% CI, 0.87-0.92) 3
• The same meta-analysis showed recorded sleep time was significantly higher by 13% for laboratory compared with portable studies 3

Impact on Clinical Decision Making

Diagnostic Accuracy

• The American Academy of Sleep Medicine (AASM) acknowledges that due to technical limitations, HSATs may underestimate the severity of OSA 1
• In a study by Masa et al., home-based therapeutic decisions were adequate when AHI was high but deficient in patients with mild to moderate AHI 1
• In a head-to-head study of 100 children, the disparity between PSG and HSAT could have significantly affected clinical management decisions in 23% of patients 1

Patient Subgroups at Higher Risk for Underestimation

• Older patients are at higher risk for underestimation as age significantly correlates with time awake during sleep studies 2
• Patients with mild-to-moderate OSA are more likely to have their condition missed or underestimated by HSATs 4
• Patients with positional sleep apnea often underestimate their proportion of supine sleep, which can lead to underestimation of OSA severity during home testing 5

Clinical Implications and Recommendations

When to Use HSATs

• HSATs should be reserved for patients with high pre-test probability for moderate to severe OSA rather than any individual with suspected OSA 4
• Patients with low pre-test probability for moderate to severe OSA are less likely to have confirmatory HSAT results (61% vs 84% in high pre-test probability group) 4
• Factors predicting non-diagnostic HSAT include age ≤50, female gender, non-enlarged neck circumference, and absence of loud snoring 4

Interpreting HSAT Results

• Clinicians should recognize the underestimation limitation of HSATs, which directly affects diagnostic phenotyping and therapeutic decisions 2
• When interpreting HSAT results, consider that approximately 54% of individuals with negative HSAT may still have OSA when tested with PSG 4
• The AASM recommends that raw HSAT data be reviewed and interpreted by a physician who is either board-certified in sleep medicine or overseen by a board-certified sleep medicine physician 1

Cost Considerations

• Despite limitations, the cost of home studies ranges from 35% to 88% lower than laboratory studies across various countries 3
• However, these lower costs are partially offset by the higher rate of inadequate examinations with HSATs 3

Common Pitfalls and Caveats

• Relying solely on AHI as the only measurement for OSA diagnosis and severity assessment is an oversimplification that may prevent thorough understanding of the condition 6
• Automatic scoring algorithms in HSATs have limited diagnostic accuracy and are not set up to detect other abnormal findings that may indicate underlying pulmonary disease 1
• HSATs typically do not include CO2 monitoring, which is important for detecting hypoventilation, especially in pediatric populations 1
• Patients often underestimate their proportion of supine sleep compared to values measured in an HST, which can affect the severity of positional OSA 5