Goodness-of-Fits of the Spirometric Reference Values for Koreans and USA Caucasians to Spirometry Data from Residents of a Region within Chungbuk Province

BACKGROUND: Korean regression models for spirometric reference values are different from those of Americans. Using spirometry results of Korean adults, goodness-of-fits of the Korean and the USA Caucasian regression models for forced vital capacity (FVC) and forced expiratory volume in one second (FEV(1)) were compared. METHODS: The number of study participants was 2,360 (1,124 males and 1,236 females). Spirometry was performed under the guidelines of the American Thoracic Society and the European Respiratory Society. After excluding unsuitable participants, spirometric data for 729 individuals (105 males and 624 females) was included in the statistical analysis. The estimated FVC and FEV(1) values were compared with those measured. Goodness-of-fits for Korean and USA Caucasian models were compared using an F-test. RESULTS: In males, the expected values of FVC and FEV(1) using the Korean model were 12.5% and 5.7% greater than those measured, respectively. The corresponding values for the USA Caucasian model were 3.5% and 0.6%. In females, the difference in FVC and FEV(1) were 13.5% and 7.7% for the Korean model, and 6.3% and 0.4% for the USA model, respectively. Goodness-of-fit for the Korean model regarding FVC was not good to the study population, but the Korean regression model for FEV(1), and the USA Caucasian models for FVC and FEV(1) showed good fits to the measured data. CONCLUSION: These results suggest that the USA Caucasian model correlates better to the measured data than the Korean model. Using reference values derived from the Korean model can lead to an overestimation regarding the prevalence of abnormal lung function.