title: New predictive equations for spirometric reference values and comparison with Morris equation in a Korean population.
abstract: OBJECTIVE
  The clinical importance of the differences between actual and predicted spirometric indices in non-Western populations is poorly defined. This study evaluated the differences between the spirometric values derived from Morris equation, traditionally used in South Korea, and the actual values, in the classification and detection of patients with respiratory diseases, and developed new predictive equations for the calculation of reference spirometric values for healthy Koreans.
  
  
  METHODS
  Data derived from a subset of the population who completed the initial baseline survey of the Korean Health and Genome Study were used to develop new predictive equations for spirometric reference values, using multiple linear regression. The effects of the new equations relative to those of Morris on the detection and classification of patients with respiratory diseases were then evaluated.
  
  
  RESULTS
  In total, 9999 people completed the baseline survey; a subgroup of 1314 met the study inclusion criteria and were used to develop the new predictive equations. Morris equation are 53.8% less accurate in detecting people with restrictive disorders and 15.8% less accurate in estimating the severity of COPD than the newly derived equations, although the differences between values derived from the traditional equations and values from the new equations were as small as 3.3-7.6%.
  
  
  CONCLUSIONS
  The use of spirometric reference values that underestimate the actual parameters, despite the small differences, may have a significant influence on the detection of patients with restrictive disorders and the staging of COPD.
authors.affiliation: Division of HIV and TB Control, Korea Center for Disease Control and Prevention, Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine and Lung Institute, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Chang-Hoon
authors.initials: CH
authors.lastname: Lee
authors.forename: Ju-Young
authors.initials: JY
authors.lastname: Lee
authors.forename: Eun-Jung
authors.initials: EJ
authors.lastname: Jang
authors.forename: Keun-Yong
authors.initials: KY
authors.lastname: Park
authors.forename: Hyun-Woo
authors.initials: HW
authors.lastname: Han
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006306:Health Surveys; D006801:Humans; D007723:Korea; D008171:Lung Diseases / Q000175:diagnosis / Q000208:ethnology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D011237:Predictive Value of Tests; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000208:ethnology / Q000503:physiopathology*; D012016:Reference Values; D012129:Respiratory Function Tests; D013147:Spirometry / Q000379:methods / Q000592:standards*