title: Development of a spirometry T-score in the general population.
abstract: OBJECTIVE
  Spirometry values may be expressed as T-scores in standard deviation units relative to a reference in a young, normal population as an analogy to the T-score for bone mineral density. This study was performed to develop the spirometry T-score.
  
  
  METHODS
  T-scores were calculated from lambda-mu-sigma-derived Z-scores using a young, normal age reference. Three outcomes of all-cause death, respiratory death, and COPD death were evaluated in 9,101 US subjects followed for 10 years; an outcome of COPD-related health care utilization (COPD utilization) was evaluated in 1,894 Korean subjects followed for 4 years.
  
  
  RESULTS
  The probability of all-cause death appeared to remain nearly zero until -1 of forced expiratory volume in 1 second (FEV1) T-score but increased steeply where FEV1 T-score reached below -2.5. Survival curves for all-cause death, respiratory death, COPD death, and COPD utilization differed significantly among the groups when stratified by FEV1 T-score (P<0.001). The adjusted hazard ratios of the FEV1 T-score for the four outcomes were 0.54 (95% confidence interval, 0.48-0.60), 0.43 (95% CI: 0.37-0.50), 0.30 (95% CI: 0.24-0.37), and 0.69 (95% CI: 0.59-0.81), respectively, adjusting for covariates (P<0.001).
  
  
  CONCLUSIONS
  The spirometry T-score could predict all-cause death, respiratory death, COPD death, and COPD utilization.
authors.affiliation: Department of Pulmonary and Critical Care Medicine, Clinical Research Center for Chronic Obstructive Airway Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Sei Won
authors.initials: SW
authors.lastname: Lee
authors.affiliation: Department of Pulmonary and Critical Care Medicine, Haeundae Paik Hospital, Inje University College of Medicine, Busan, Korea.
authors.forename: Hyun Kuk
authors.initials: HK
authors.lastname: Kim
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Seunghee
authors.initials: S
authors.lastname: Baek
authors.affiliation: Division of Pulmonary, Department of Internal Medicine, Institute of Chest Disease, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Ji-Ye
authors.initials: JY
authors.lastname: Jung
authors.affiliation: Division of Pulmonary, Department of Internal Medicine, Institute of Chest Disease, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Young Sam
authors.initials: YS
authors.lastname: Kim
authors.affiliation: Department of Pulmonary and Critical Care Medicine, Clinical Research Center for Chronic Obstructive Airway Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Jae Seung
authors.initials: JS
authors.lastname: Lee
authors.affiliation: Department of Pulmonary and Critical Care Medicine, Clinical Research Center for Chronic Obstructive Airway Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Sang-Do
authors.initials: SD
authors.lastname: Lee
authors.affiliation: Department of Preventive Medicine and Environmental Health, University of Kentucky College of Public Health, Lexington, KY, USA.
authors.forename: David M
authors.initials: DM
authors.lastname: Mannino
authors.affiliation: Department of Pulmonary and Critical Care Medicine, Clinical Research Center for Chronic Obstructive Airway Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Yeon-Mok
authors.initials: YM
authors.lastname: Oh
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002423:Cause of Death; D003695:Delivery of Health Care / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010043:Outcome and Process Assessment, Health Care; D011237:Predictive Value of Tests; D057216:Propensity Score; D016016:Proportional Hazards Models; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000401:mortality; D012016:Reference Values; D056910:Republic of Korea / Q000453:epidemiology; D013147:Spirometry / Q000379:methods / Q000592:standards / Q000706:statistics & numerical data; D011795:Surveys and Questionnaires; D014481:United States / Q000453:epidemiology
keywords: COPD; T-score; spirometry