474 Phenotyping of patients with Moderate to Severe OSA on Polysomnography after Negative Home Sleep Apnea Testing

Introduction Polysomnography (PSG) is the gold standard for the diagnosis of obstructive sleep apnea (OSA). Given cost, insurance restrictions and in some cases limited access to sleep center testing, the use of home based sleep apnea testing is becoming increasingly more common. A proportion of patients with technically adequate HSAT who are negative end up having significant disease on PSG. The characteristics of patients who are found to have moderate to severe sleep apnea on polysomnogram (PSG) after a negative home sleep apnea test (HSAT) are not known. We aim to phenotype these patients. Methods We conducted a retrospective chart review from March 2018 to February 2020. A total of 953 adult patients (18 years old and older) underwent HSAT, 248 tests resulted negative (apnea-hypopnea index <5/h). Out of the negative HSAT, 17 patients had moderate to severe obstructive sleep apnea on PSG. Those were included for analysis. Data on patient characteristics such as age, body mass index (BMI), gender, STOP-BANG, ESS and comorbidities was gathered. Respiratory disturbance index, recording time, flow time, oximetry time on HSAT was recorded. PSG recording time, baseline AHI, supine AHI and non-supine AHI were also noted. Technically inadequate HSAT were excluded from analysis. Results The percentage of patients with negative HSAT who were found to have moderate to severe sleep apnea on PSG and were included for analysis was 6.85% (n17). Mean age was 41 years. Mean BMI was 33 kg/m2. Common comorbidities were hypertension (29%), asthma (17.6 %), depression (17.6%), anxiety (11.7%) and reflux (5.9%). Average ESS was 11.7 and STOP-BANG was 3.8. The mean recording time was 477 minutes, flow time 391 minutes and oximetry time was 426 minutes on HSAT. Average PSG recording time was 433 minutes. Average AHI was 24 with supine being 33.2/h and non-supine 17.9/h. Conclusion A proportion of patients with negative HSAT have moderate to severe OSA on follow-up polysomnogram. These patients were young, with lower-class obesity, more positional OSA, and no associated complex comorbidities. Re-evaluation of current diagnostic algorithms and further research is needed to phenotype this at-risk group, as first-line PSG may be more cost-effective and efficient. Support (if any):

424 Advanced gestational age is a predictor of non-completion of sleep apnea testing in pregnancy

Introduction Sleep apnea is emerging as an important and underdiagnosed comorbidity in pregnancy. Screening, diagnosis, and initiation of therapy are all time-sensitive processes during the dynamic progression of gestation. Completion of referral and testing for sleep apnea during pregnancy requires a significant commitment of time and effort on the part of the pregnant patient. We evaluated for predictors of non-completion of sleep apnea testing within our obstetric-sleep referral pipeline, in an effort to inform and optimize future referrals. Methods We performed a retrospective chart-review of 405 pregnant patient referrals for sleep apnea evaluation at the University of Wisconsin-Madison/UnityPoint sleep apnea pregnancy clinic. We used logistic regression analysis to determine predictors of lack of completion of sleep apnea testing. Results The vast majority of referrals (>95%) were triaged directly to home sleep apnea testing with the Alice PDX portable device, rather than a sleep clinic visit. The overall rate of referral non-completion was 59%. Predictors of non-completion of sleep apnea evaluation in our pregnant population included higher gestational age (GA) at referral (1–12 wks GA: 30%, 13–26 wks GA: 31%, and 27–40 wks GA: 57% non-completers, p=0.006) and multiparity with 1 or more living children (65% non-completers if any living children, compared to 45% non-completers if no living children, p=0.002). Age, race, and transportation were not predictors of failure to complete sleep apnea testing. Conclusion We have identified several predictors of pregnant patients’ failure to complete sleep apnea evaluation with objective home sleep apnea testing after referral from obstetrics. Not surprisingly, higher gestational age emerged as a strong negative predictor of referral completion, with >50% of patients referred in the third trimester not completing sleep apnea testing. Early screening and referral for sleep apnea evaluation in pregnancy should be prioritized, given the time-sensitive nature of diagnosis and therapy initiation, and demonstrated reduced completion of referrals in advanced pregnancy. Support (if any) None