Comparison of apnoea–hypopnoea index and oxygen desaturation index when identifying obstructive sleep apnoea using type-4 sleep studies

Chamara V. Senaratna, Adrian Lowe, Jennifer L. Perret, Caroline Lodge, Gayan Bowatte, Michael J. Abramson, Bruce R. Thompson, Garun Hamilton, Shyamali C. Dharmage

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The concordance of different indices from type-4 sleep studies in diagnosing and categorising the severity of obstructive sleep apnoea is not known. This is a critical gap as type-4 sleep studies are used to diagnose obstructive sleep apnoea in some settings. Therefore, we aimed to determine the concordance between flow-based apnoea–hypopnoea index (AHI flow50% ) and oxygen desaturation index (ODI 3% ) by measuring them concurrently. Using a random sub-sample of 296 from a population-based cohort who underwent two-channel type-4 sleep studies, we assessed the concordance between AHI flow50% and ODI 3% . We compared the prevalence of obstructive sleep apnoea of various severities as identified by the two methods, and determined their concordance using coefficient Kappa(κ). Participants were aged (mean ± SD) 53 ± 0.9 years (48% male). The body mass index was 28.8 ± 5.2 kg m −2 and neck circumference was 37.4 ± 3.9 cm. The median AHI flow50% was 5 (inter-quartile range 2, 10) and median ODI 3% was 9 (inter-quartile range 4, 15). The obstructive sleep apnoea prevalence reported using AHI flow50% was significantly lower than that reported using ODI 3% at all severity thresholds. Although 90% of those with moderate–severe obstructive sleep apnoea classified using AHI flow50% were identified by using ODI 3% , only 46% of those with moderate–severe obstructive sleep apnoea classified using ODI 3% were identified by AHI flow50% . The overall concordance between AHI flow50% and ODI 3% in diagnosing and classifying the severity of obstructive sleep apnoea was only fair (κ = 0.32), better for males (κ = 0.42 [95% confidence interval 0.32–0.57] versus 0.22 [95% confidence interval 0.09–0.31]), and lowest for those with a body mass index ≥ 35 (κ = 0.11). In conclusion, ODI 3% and AHI flow50% from type-4 sleep studies are at least moderately discordant. Until further evidence is available, the use of ODI 3% as the measure of choice for type-4 sleep studies is recommended cautiously.

Original languageEnglish
Article numbere12804
Number of pages8
JournalJournal of Sleep Research
Issue number5
Publication statusPublished - Oct 2019


  • agreement
  • home sleep studies
  • home sleep-testing
  • oxygen desaturation index
  • portable

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