Unveiling the Surprising Variability in Home Testing for Sleep Apnea

Unveiling the Surprising Variability in Home Testing for Sleep Apnea
In the realm of sleep disorders, sleep apnea (SA) stands out as a condition with significant health implications. Traditionally, diagnosis has relied on a single sleep study, yet recent research has illuminated the common variability in SA severity. Addressing this knowledge gap, a pioneering study embarked on evaluating the extent of this variability and determining the optimal number of tests for diagnostic accuracy. Leveraging a novel type 3 home sleep test capable of longitudinal tracking, the study scrutinized 149 adults across the United States, administering a staggering 1,184 tests in total. Subjects who reported utilizing SA treatments were excluded from analysis to ensure the purity of the investigation. With the Apnea/Hypopnea Index (AHI) as the yardstick for gauging SA severity, the study uncovered a startling reality of fluctuating scores among 69.7% of subjects upon repeat testing.

Unraveling the complexities of SA diagnosis, the study's findings herald a paradigm shift in clinical practice. Averaging 3.2 tests before confirming a positive AHI and 3.6 tests to pinpoint peak severity, the research underscores the inadequacy of single or double night sleep studies in capturing the dynamic nature of SA. Astonishingly, a significant portion of previously diagnosed subjects experienced exacerbations in severity upon reevaluation, highlighting the potential pitfalls of static diagnoses. Moreover, the study elucidates the peril faced by patients with mild to moderate SA, with a substantial percentage falling into the severe range upon longitudinal testing. Factors such as positional variation and time spent in REM sleep emerged as influential variables, further emphasizing the need for comprehensive longitudinal assessment. Ultimately, the study's insights advocate for a standardized approach to longitudinal testing, advocating for a threshold of more than three tests to enhance diagnostic accuracy and mitigate the risk of misclassification.

This study retrospective evaluated 149 adults across the U.S. that used a novel type 3 home sleep test, capable of unlimited longitudinal testing. 1,184 tests were evaluated (Mean 7.9 tests/subject; SD 6.9). Subjects who reported using SA treatments were removed from analysis. Apnea/Hypopnea Index (AHI) was assessed to determine the presence and severity of SA. A subgroup of previously diagnosed individuals were assessed for diagnostic accuracy.
On repeat testing, 69.7% of subjects had AHI scores that varied in severity. 51% had scores within the normal (<5) and abnormal range (>5). The average AHI point difference between a subject's best and worst test was 12.4 (SD 12.1). Of the subjects that were positive for SA, 52% had false negatives on their first test. An average of 3.2 (SD 1.6) test were completed before obtaining a positive AHI, and 3.6 (SD 2.2) tests before arriving at the highest recorded severity. 26.1% of previously diagnosed subjects had tests that were more severe than their original diagnosis. Of the subjects that reported having mild SA, 11%  had scores that placed them within the severe range. Of the subjects that reported having moderate SA, 38% had scores within the severe range. Factors that were found to correlate with AHI variation were variation in time spent in supine position and time spent in REM, in 12-14% of subjects. 
Longitudinal testing with an HST confirmed high night-to-night variability of AHI in the majority of SA sufferers. Patients with mild to moderate SA were at high risk for misdiagnosis or misclassification if diagnosis is based on single or double night sleep studies. This study emphasized the need to standardize longitudinal testing and suggests that >3 tests is ideal for diagnostic accuracy.

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