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Measured diffusion capacity versus prediction equation estimates in blacks without lung disease.
Gene R Pesola1, Yisa Sunmonu, Gladstone Huggins
1Division of Pulmonary/Critical Care, Department of Medicine, Harlem Hospital/Columbia University, and Harlem Lung Center, New York, N.Y. 10037, USA. grp4@columbia.edu
Respiration; International Review of Thoracic Diseases
|October 7, 2004
Summary
African-Americans have smaller lung volumes, leading to inaccurate diffusion capacity of CO (DLCO) readings when using Caucasian-based prediction equations. Adjusting these equations, such as the Miller equation by 12%, can significantly improve accuracy for this population.
Area of Science:
- Pulmonary Function Testing
- Respiratory Physiology
- Racial Disparities in Health
Background:
- Lung volumes in African-Americans are typically 10-15% lower than in Caucasians.
- Existing diffusion capacity of CO (DLCO) prediction equations, developed in Caucasians, do not account for these lung volume differences.
- This can lead to misdiagnosis of healthy Black individuals as having abnormal DLCO.
Purpose of the Study:
- To evaluate if commonly used DLCO prediction equations in the US label healthy Black subjects as abnormal.
- To investigate the impact of race-based lung volume differences on DLCO measurements.
Main Methods:
- Forty-two healthy, non-smoking Black subjects underwent DLCO testing using the single-breath method.
- Measured DLCO was compared against predictions from Miller, Knudson, and Crapo equations.
- Alveolar volume was determined using methane gas dilution and body plethysmography.
Main Results:
- Black subjects showed significantly lower average measured DLCO compared to predictions from all three equations (Miller, Knudson, Crapo).
- A high percentage of Black subjects were classified as abnormal (up to 50% or more) based on these equations.
- A 12% race correction applied to the Miller equation reduced abnormal DLCO readings in Black subjects to 2/42.
Conclusions:
- Current DLCO prediction equations overestimate DLCO in healthy African-Americans due to unadjusted lower lung volumes.
- A 12% race correction for the Miller prediction equation is a viable interim solution to reduce diagnostic errors in Black populations.
- Development of race-specific DLCO prediction equations is needed for accurate assessment in African-Americans.