title: Aging-Related Considerations When Evaluating the Forced Expiratory Volume in 1 Second (FEV1) Over Time.
abstract: Forced expiratory volume in 1 second (FEV1) over time is commonly expressed in liters and percent predicted (%Pred), or alternatively in L/m(3) and Z-scores-which approach is more clinically meaningful has not been evaluated. Because it uniquely accounts for the effect of aging on FEV1 and spirometric performance, we hypothesized that the Z-score approach is more clinically meaningful, based on associations between cardiopulmonary predictors and FEV1 over time.
  
  
  
  Using linear mixed-effects models and data from the Baltimore Longitudinal Study on Aging, including 501 white participants aged 40-95 who had completed at least three longitudinal spirometric assessments, we evaluated the associations between cardiopulmonary predictors (obesity, smoking status, hypertension, chronic bronchitis, diabetes mellitus, and myocardial infarction) and FEV1 over time, in liters, %Pred, L/m(3), and Z-scores.
  
  
  
  Mean baseline values for FEV1 were 3.240L, 96.4%Pred, 0.621L/m(3), and -0.239 as a Z-score (40.6th percentile). The annual decline in FEV1 was 0.040L, 0.234 %Pred, 0.007L/m(3), and 0.008 Z-score units. Baseline age was associated with FEV1 over time in liters and L/m(3) (p < .001), and included a time interaction for %Pred (p < .001), but was not associated with Z-scores (p = .933). The associations of cardiopulmonary predictors with FEV1 over time were all significant when using Z-scores (p < .05), but varied for other methods of expressing FEV1.
  
  
  
  A Z-score approach is more clinically meaningful when evaluating FEV1 over time, as it accounted for the effect of aging and was more frequently associated with multiple cardiopulmonary predictors.
authors.affiliation: Veterans Affairs Clinical Epidemiology Research Center, West Haven, Connecticut. Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut. carlos.fragoso@yale.edu.
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Vaz Fragoso
authors.affiliation: Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Gail
authors.initials: G
authors.lastname: McAvay
authors.affiliation: Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Peter H
authors.initials: PH
authors.lastname: Van Ness
authors.affiliation: Department of Neurology, University of Tennessee Health Science Center, Memphis, Tennessee.
authors.forename: E Jeffrey
authors.initials: EJ
authors.lastname: Metter
authors.affiliation: Harbor Hospital, National Institute on Aging, Baltimore, Maryland.
authors.forename: Luigi
authors.initials: L
authors.lastname: Ferrucci
authors.affiliation: Veterans Affairs Clinical Epidemiology Research Center, West Haven, Connecticut. Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: H Klar
authors.initials: HK
authors.lastname: Yaggi
authors.affiliation: Veterans Affairs Clinical Epidemiology Research Center, West Haven, Connecticut. Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: John
authors.initials: J
authors.lastname: Concato
authors.affiliation: Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Gill
mesh_terms: D000368:Aged; D000375:Aging / Q000502:physiology*; D029481:Bronchitis, Chronic / Q000453:epidemiology*; D018450:Disease Progression; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology*; D054624:Health Status Disparities; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000453:epidemiology*; D009765:Obesity / Q000453:epidemiology; D011237:Predictive Value of Tests; D012107:Research Design; D012129:Respiratory Function Tests / Q000379:methods; D012131:Respiratory Insufficiency / Q000175:diagnosis / Q000503:physiopathology; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology*; D013997:Time Factors; D014481:United States / Q000453:epidemiology
keywords: Aging; Cardiovascular diseases; Epidemiology; Lung diseases; Spirometry