Prediction equations for single-breath diffusing capacity in subjects aged 65 to 85 years

Area of Science:

• Pulmonology
• Respiratory Physiology
• Geriatric Medicine

Background:

• Current interpretation of diffusing capacity of the lung for carbon monoxide (Dlco) in seniors relies on equations primarily derived from younger adults.
• This practice may lead to inaccurate assessments of lung function in the elderly population.

Purpose of the Study:

• To establish reference equations for single-breath Dlco in healthy, never-smoking, white, European adults aged 65 to 85 years.
• To compare these new predictions with existing equations used for middle-aged adults.

Main Methods:

• A randomly selected cohort of 431 healthy, never-smoking adults (262 women, 169 men) aged 65-85 participated.
• Standard spirometry, plethysmography for lung volumes, and single-breath Dlco (hemoglobin-corrected) were performed per ATS/ERS guidelines.
• Reference values and limits of normal were determined using a piecewise polynomial model.

Main Results:

• Age, height, and body size significantly influence Dlco and Dlco/Va in older adults.
• Equations derived from middle-aged populations consistently underestimated Dlco in the elderly cohort (by 2.1%–37.8%).
• Dlco/Va was either overestimated (up to 39.8%) or underestimated (up to 22.2%) when using existing equations.

Conclusions:

• Accurate interpretation of lung diffusing capacity in older adults necessitates age- and origin-specific prediction equations.
• The study highlights the inadequacy of current prediction models for the elderly, emphasizing the need for updated reference values.