Racial discordance in spirometry comparing four commonly used reference equations to the National Health and...

Area of Science:

• Pulmonary Medicine
• Respiratory Diagnostics
• Clinical Epidemiology

Background:

• Accurate lung function diagnosis relies on population-specific reference equations.
• Current guidelines suggest National Health and Examination Survey III (NHANES III) data for US patients.
• Previous studies noted interpretation discrepancies in Caucasian patients using older versus NHANES III equations.

Purpose of the Study:

• To evaluate interpretation discordance in spirometry for African-American patients using various reference equations.
• To compare classifications derived from older equations against the NHANES III reference data.

Main Methods:

• Cross-sectional analysis of 4463 African-American patients undergoing spirometry.
• Classification into normal, restricted, obstructed, or mixed using ATS/ERS guidelines.
• Comparison of spirometry interpretations using Crapo, Knudson, Morris, Glindmeyer, and NHANES III equations.

Main Results:

• Significant interpretation discordance observed when comparing older equations to NHANES III.
• Highest discordance rates with Morris (24.6%), Knudson (26.4%), and Glindmeyer (20.1%) equations versus NHANES III.
• Tendency for Knudson, Morris, and Glindmeyer to under-classify restriction and for Crapo, Morris, and Glindmeyer to over-classify obstruction.

Conclusions:

• Reliance on older spirometry reference equations (Crapo, Morris, Knudson, Glindmeyer) leads to significant interpretation discordance in African-American patients.
• NHANES III equations provide a more consistent reference for this population.
• Clinical use of spirometry in African-Americans necessitates careful selection of appropriate, updated reference equations.