Rationale: There are many reference equations for the measurement of DLCO. However the testing methodologies vary and there are no well-documented studies that develop reference equations for DLCO and alveolar volume (VA) in middle aged and older populations.
Objectives: 1. Develop reference equations for DLCO in a middle aged population using the current ATS/ERS guidelines; 2. Compare the equations with those commonly used in laboratories around the world.
Methods: Healthy subjects (498 male and 474 female) aged 45 to 71 years were recruited as part of a larger epidemiological study. All participants completed a respiratory questionnaire and had spirometry and single breath DLCO (corrected for haemoglobin) measurements following ATS/ERS guidelines.
Results: The mean age was 58 years for males and 57 years for females. For males, factors that predicted DLCO were: Height, Age and Age * Height interaction and being an ex-smoker. For females, factors that predicted DLCO were: Height, Age, Weight and an Age * Height interaction.
Conclusion: We have described new prediction equations for DLCO in a middle-aged population that require validation in other populations.