title: Agreement between fixed-ratio and lower limit of normal spirometry interpretation protocols decreases with age: is there a need for a new GOLD standard?
abstract: OBJECTIVE
  To assess concordance between the fixed 70% ratio cutoff point with the fixed percent predicted values (Fixed-ratio) and the lower limit of normal (LLN) algorithms in interpreting spirometry results in an older population.
  
  
  METHODS
  Spirometries were interpreted using Third National Health and Nutrition Examination Survey reference equations for 2319 workers.
  
  
  RESULTS
  The Fixed-ratio algorithm characterized 34.5% (n = 801) results as abnormal, compared with 29.7% (n = 689) by the LLN. There were almost twice as many obstructive and mixed airways spirometries identified under the Fixed-ratio compared to LLN. Rates of restrictive pattern physiology were virtually the same under each algorithm. Overall agreement between the algorithms decreased with age from "almost perfect" for those younger than 60 years to "substantial" for those older than 80 years.
  
  
  CONCLUSIONS
  This study found age-related discordance between two algorithms possibly related to the lack of reference equations and standards for individuals older than 80 years.
authors.affiliation: Department of Occupational and Environmental Health, College of Public Health, The University of Iowa, Iowa City, IA 52242, USA. marek-mikulski@uiowa.edu
authors.forename: Marek A
authors.initials: MA
authors.lastname: Mikulski
authors.forename: Alicia K
authors.initials: AK
authors.lastname: Gerke
authors.forename: Spencer
authors.initials: S
authors.lastname: Lourens
authors.forename: Thomas
authors.initials: T
authors.lastname: Czeczok
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Sprince
authors.forename: Anthony S
authors.initials: AS
authors.lastname: Laney
authors.forename: Laurence J
authors.initials: LJ
authors.lastname: Fuortes
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D003661:Decision Support Techniques; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D016015:Logistic Models; D008173:Lung Diseases, Obstructive / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009749:Nutrition Surveys; D012015:Reference Standards; D015203:Reproducibility of Results; D012131:Respiratory Insufficiency / Q000175:diagnosis*; D013147:Spirometry / Q000592:standards*; D014797:Vital Capacity