0519 Predictors of False Negative HSATs in a Veteran Population

Abstract Introduction Obstructive sleep apnea (OSA) is a common chronic condition associated with significant morbidity and mortality. Polysomnography (PSG) is the gold standard for diagnosis but is not always readily available. American Academy of Sleep Medicine (AASM) 2017 guidelines recommend in-lab PSG if a patient with high pretest probability of OSA has a negative home sleep apnea test (HSAT) defined as AHI 5 events/hour. At our institution, the threshold for obtaining an in-lab PSG has been broadened to include pAHI 10 events/hour. We investigated the validity of this threshold and analyzed co-morbidities and other predictors of false negative HSATs. Methods We reviewed 306 consecutive WatchPAT®️ (Itmar Medical, Ltd.) HSATs between January 2021 and December 2022 with a peripheral arterial tonometry–derived apnea-hypopnea index (pAHI) 10. False negative HSAT was defined as pAHI 10 with in-lab PSG AHI 5 and true negative HSAT was defined as pAHI 10 with in-lab PSG AHI 5. The in-lab PSG results were categorized as mild, moderate, or severe OSA. Demographic data and co-morbidity information were gathered for these patients. Chi-squared test was used for statistical analysis. Results Demographic data were well balanced between the two groups including male gender, age, and BMI. 131 patients met criteria for in-lab PSG. Of these, 64 (49%) were false negative and 67 (51%) were true negative. Out of the false negative HSATs, 65% were mild whereas 35% were moderate or severe OSA. These false negative HSATs were significantly associated with diabetes (p=0.01), hypertension (p=0.001), and patients with hypertension taking two or more anti-hypertensive medications (p=0.001). Conclusion False negative HSATs were common in the evaluation of OSA in our veteran population with a notable percentage of moderate to severe OSA on in-lab PSG even when the threshold was raised to pAHI 10. False negative HSATs were significantly associated with diabetes, hypertension, and patients on two or more anti-hypertensive medications. AASM guidelines recommend in-lab PSG for negative HSATs. Our study proposes that we should consider increasing our threshold to repeat a gold-standard in-lab PSG in patients with a pAHI 10, especially those with hypertension or diabetes. Support (if any)