New reference equations for forced spirometry in elderly persons

Area of Science:

• Pulmonology
• Geriatric Medicine
• Biostatistics

Background:

• Accurate lung function prediction equations are crucial for diagnosing respiratory conditions in older adults.
• Existing prediction equations, often derived from younger populations, may not accurately reflect lung function in the elderly.
• Population-specific variations necessitate the development of tailored reference equations.

Purpose of the Study:

• To identify and derive new prediction equations for lung function parameters in healthy, nonsmoking older adults.
• To evaluate the applicability of existing prediction equations from younger populations to the elderly.
• To examine the need for population-specific reference equations for older individuals.

Main Methods:

• Measured forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and peak expiratory flow (PEF) in 651 ambulatory volunteers aged 65-86.
• Included 261 asymptomatic, nonsmoking subjects representative of the Croatian Mediterranean population.
• Derived sex-specific reference equations and lower limits of normal using a linear model with height and age as predictors.

Main Results:

• New reference equations for FVC and FEV1 showed agreement with those derived from younger adults.
• Existing European and U.S. elderly prediction equations systematically overpredicted lung function in the Croatian sample (14-34% for FVC, 10-20% for FEV1).
• These discrepancies led to misclassification, with 25-55% of subjects identified as having below-normal FVC using existing equations.

Conclusions:

• Lung volume prediction equations were more reliable than those for PEF.
• Existing elderly prediction equations are inappropriate for the Croatian population due to systematic overprediction.
• The findings strongly support the development of age- and population-specific reference equations for accurate lung function assessment in older adults.