ORIGINAL ARTICLE Scoring criteria for portable monitor recordings: a comparison of four hypopnoea definitions in a population-based cohort Sopharat Vat, 1,2 Jose Haba-Rubio, 1 Mehdi Tafti, 1,3 Nadia Tobback, 1 Daniela Andries, 1 Raphael Heinzer 1,4 ▸ Additional material is published online only. To view please visit the journal online (http://dx.doi.org/10.1136/ thoraxjnl-2014-205982). 1 Centre for Investigation and Research in Sleep (CIRS), Lausanne University Hospital (CHUV), Lausanne, Switzerland 2 Pulmonary Medicine Department, University Hospital of Montreal (CHUM), Montreal, Quebec, Canada 3 Centre for Integrative Genomics, University of Lausanne (UNIL), Lausanne, Switzerland 4 Pulmonary Department (CHUV), Lausanne University Hospital, Lausanne, Vaud, Switzerland Correspondence to Dr Raphaël Heinzer, Center for Investigation and Research in Sleep (CIRS), University Hospital of Lausanne, Lausanne 1011, Switzerland; Raphael.Heinzer@chuv.ch SV and JH-R are joint first authors. Received 1 August 2014 Revised 7 July 2015 Accepted 22 July 2015 Published Online First 20 August 2015 To cite: Vat S, Haba- Rubio J, Tafti M, et al. Thorax 2015;70: 1047–1053. ABSTRACT Rationale Limited-channel portable monitors (PMs) are increasingly used as an alternative to polysomnography (PSG) for the diagnosis of obstructive sleep apnoea (OSA). However, recommendations for the scoring of PM recordings are still lacking. Pulse-wave amplitude (PWA) drops, considered as surrogates for EEG arousals, may increase the detection sensitivity for respiratory events in PM recordings. Objectives To investigate the performance of four different hypopnoea scoring criteria, using 3% or 4% oxygen desaturation levels, including or not PWA drops as surrogates for EEG arousals, and to determine the impact of measured versus reported sleep time on OSA diagnosis. Methods Subjects drawn from a population-based cohort underwent a complete home PSG. The PSG recordings were scored using the 2012 American Academy of Sleep Medicine criteria to determine the apnoea–hypopnoea index (AHI). Recordings were then rescored using only parameters available on type 3 PM devices according to different hypopnoea criteria and patients-reported sleep duration to determine the ‘portable monitor AHIs’ (PM-AHIs). Main results 312 subjects were included. Overall, PM- AHIs showed a good concordance with the PSG-based AHI although it tended to slightly underestimate it. The PM-AHI using 3% desaturation without PWA drops showed the best diagnostic accuracy for AHI thresholds of ≥5/h and ≥15/h (correctly classifying 94.55% and 93.27% of subjects, respectively, vs 80.13% and 87.50% with PWA drops). There was a significant but modest correlation between PWA drops and EEG arousals (r=0.20, p=0.0004). Conclusion Interpretation of PM recordings using hypopnoea criteria which include 3% desaturation without PWA drops as EEG arousal surrogate showed the best diagnosis accuracy compared with full PSG. INTRODUCTION Obstructive sleep apnoea (OSA) is a highly preva- lent disease associated with neurocognitive 1 impair- ment and cardiovascular morbidity. 23 Despite an increased awareness, studies have shown that >75% of the patients remain undiagnosed and untreated. 4 To date, attended in-laboratory poly- somnography (PSG) is considered the gold standard for OSA diagnosis. 5 However, considering the cost, technical complexity and human resources required for PSG, unattended portable monitor (PM) devices have been proposed as an alternative tech- nique for the diagnosis of OSA. Recent studies suggest that the diagnosis of OSA with PM devices can be as accurate as with PSG in selected popula- tions. 6–11 Current guidelines from the American Academy of Sleep Medicine (AASM) recommend the use of unattended PMs for the diagnosis of OSA only in combination with a comprehensive clinical assessment in patients with a high pre-test probability of moderate-to-severe OSA and without comorbid sleep disorder or major comorbid medical disorders. 6 12 The AASM recommends type 3 PM devices, which include an average of 4–7 channels with at least a measurement of airflow, respiratory effort and blood oxygenation. 6 13 There are however concerns regarding the inter- pretation of PM recordings because of the lack of an EEG signal for the determination of sleep periods and arousals. Frequency of respiratory events identified with PM devices (PM-apnoea– hypopnoea index (AHI)) is calculated based on the Key messages What is the key question? ▸ How should sleep portable monitor (PM) recordings be scored in the absence of EEG-defined arousals and sleep duration? What is the bottom line? ▸ Hypopnoea criteria using 3% oxygen desaturation level without pulse-wave amplitude (PWA) drops as EEG arousal surrogate accurately classified mild-to-moderate obstructive sleep apnoea (OSA), whereas including PWA drops may provide a higher accuracy only for diagnosis of severe OSA. Why read on? ▸ This study allows direct comparison between complete polysomnography and type 3 PM recorders, provides new insights on the scoring of respiratory events with PM recordings and evaluates a novel way to define respiratory events with the use of PWA drops as surrogates for EEG arousals. Vat S, et al. Thorax 2015;70:1047–1053. doi:10.1136/thoraxjnl-2014-205982 1047 Sleep on May 23, 2020 by guest. Protected by copyright. http://thorax.bmj.com/ Thorax: first published as 10.1136/thoraxjnl-2014-205982 on 20 August 2015. Downloaded from