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Abnormal predicted diffusion capacities in healthy Asians: an inequality with a solution.
Gene R Pesola1, Gladstone Huggins, Tsering Y Sherpa
1Division of Pulmonary/Critical Care, Department of Medicine, Harlem Hospital/Columbia University and Harlem Lung Center, New York, NY 10037, USA. grp4@columbia.edu
Respiration; International Review of Thoracic Diseases
|July 11, 2006
Summary
Caucasian prediction equations for diffusing capacity of the lungs for carbon monoxide (DLCO) incorrectly label healthy Asians as abnormal due to smaller lung volumes. A Chinese-derived DLCO prediction equation is recommended for all Asians in the US.
Area of Science:
- Pulmonary Physiology
- Respiratory Medicine
- Clinical Diagnostics
Background:
- Asian lung volumes are 10-15% smaller than Caucasian lung volumes.
- Caucasian-derived prediction equations for diffusing capacity of the lungs for carbon monoxide (DLCO) may misdiagnose healthy Asians.
Purpose of the Study:
- To evaluate if healthy Asians are mislabeled as abnormal using Caucasian-derived DLCO prediction equations.
- To assess the validity of a Chinese-derived DLCO prediction equation in non-Chinese Asians.
Main Methods:
- Forty-one healthy Asians underwent DLCO testing.
- Measured DLCO was compared against four prediction equations: Miller, Knudson, Crapo (Caucasian-derived), and a Chinese-derived equation.
- Alveolar volume was estimated using gas dilution and plethysmography.
Main Results:
- Caucasian-derived equations (Miller, Knudson, Crapo) resulted in 10-50% of healthy Asians being incorrectly classified as abnormal.
- The Chinese-derived DLCO prediction equation showed no significant difference from measured Asian DLCO.
- Caucasian subjects showed no significant difference in lung volumes compared to their predicted values, unlike Asians.
Conclusions:
- Caucasian DLCO prediction equations are inadequate for healthy Asians due to unaddressed lung volume differences.
- A Chinese-derived DLCO prediction equation is accurate for non-Chinese Asians and should replace Caucasian equations in the US for all Asian populations.