title: The new AASM criteria for scoring hypopneas: impact on the apnea hypopnea index.
abstract: OBJECTIVE
  To compare apnea-hypopnea indices (AHIs) derived using 3 standard hypopnea definitions published by the American Academy of Sleep Medicine (AASM); and to examine the impact of hypopnea definition differences on the measured prevalence of obstructive sleep apnea (OSA).
  
  
  METHODS
  Retrospective review of previously scored in-laboratory polysomnography (PSG).
  
  
  METHODS
  Two tertiary-hospital clinical sleep laboratories.
  
  
  METHODS
  328 consecutive patients investigated for OSA during a 3-month period.
  
  
  METHODS
  N/A.
  
  
  RESULTS
  AHIs were originally calculated using previous AASM hypopnea scoring criteria (AHI(Chicago)), requiring either >50% airflow reduction or a lesser airflow reduction with associated >3% oxygen desaturation or arousal. AHIs using the "recommended" (AHI(Rec)) and the "alternative" (AHI(Alt)) hypopnea definitions of the AASM Manual for Scoring of Sleep and Associated Events were then derived in separate passes of the previously scored data. In this process, hypopneas that did not satisfy the stricter hypopnea definition criteria were removed. For AHI(Rec), hypopneas were required to have > or =30% airflow reduction and > or =4% desaturation; and for AHI(Alt), hypopneas were required to have > or =50% airflow reduction and > or =3% desaturation or arousal. The median AHI(Rec) was approximately 30% of the median AHI(Chicago), whereas the median AHI(Alt), was approximately 60% of the AHI(Chicago), with large, AHI-dependent, patient-specific differences observed. Equivalent cut-points for AHI(Rec) and AHI(Alt), compared to AHI(Chicago) cut-points of 5, 15, and 30/h were established with receiver operator curves (ROC). These cut-points were also approximately 30% of AHI(Chicago) using AHI(Rec) and 60% of AHI(Chicago) using AHI(Alt). Failure to adjust cut-points for the new criteria would result in approximately 40% of patients previously classifled as positive for OSA using AHI(Chicago) being negative using AHI(Rec) and 25% being negative using AHI(Alt).
  
  
  CONCLUSIONS
  This study demonstrates that using different published standard hypopnea definitions leads to marked differences in AHI. These results provide insight to clinicians and researchers in interpreting results obtained using different published standard hypopnea definitions, and they suggest that consideration should be given to revising the current scoring recommendations to include a single standardized hypopnea definition.
authors.affiliation: Institute for Breathing and Sleep, Austin Health, Heidelberg, Victoria, Australia. Warren.Ruehland@austin.org.au
authors.forename: Warren R
authors.initials: WR
authors.lastname: Ruehland
authors.forename: Peter D
authors.initials: PD
authors.lastname: Rochford
authors.forename: Fergal J
authors.initials: FJ
authors.lastname: O'Donoghue
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Pierce
authors.forename: Parmjit
authors.initials: P
authors.lastname: Singh
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Thornton
mesh_terms: D000328:Adult; D003431:Cross-Cultural Comparison; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D017286:Polysomnography / Q000145:classification* / Q000592:standards; D017410:Practice Guidelines as Topic; D012016:Reference Values; D012189:Retrospective Studies; D020181:Sleep Apnea, Obstructive / Q000145:classification / Q000175:diagnosis* / Q000453:epidemiology; D014481:United States; D014739:Victoria
chemical_list: D010100:Oxygen