A physiologically based model for spirometric reference equations in adults.

Area of Science:

• Pulmonary Medicine
• Biostatistics
• Physiological Modeling

Background:

• Spirometric reference equations are crucial for diagnosing lung diseases.
• Current models often prioritize statistical fit over physiological interpretability.
• A need exists for models allowing direct population comparisons.

Purpose of the Study:

• To evaluate the clinical utility of the Lubiński model against other spirometric equation models.
• To assess the comparability of Polish and Swedish populations using Lubiński model-based equations.
• To determine the clinical usefulness of established reference equations in Swedish adults.

Main Methods:

• Comparative analysis of multiple linear, piecewise polynomial, exponential with splines, and Lubiński models.
• Optimization of models using a Swedish adult population sample with high-quality spirometry data.
• Evaluation of model performance based on predictive accuracy and proportion of subjects below the lower limit of normal.

Main Results:

• The Lubiński model demonstrated clinical utility comparable to other evaluated models for the Swedish population.
• Significant differences were observed between Polish and Swedish populations when using optimized reference equations.
• Piecewise polynomial equations showed adequate proportions below the lower limit of normal, unlike exponential equations with splines.

Conclusions:

• The Lubiński model is clinically as useful as existing models and recommended for future spirometric reference equations.
• The model facilitates interpretable comparisons between different populations.
• Exponential equations with splines are not recommended for Swedish adults due to excessively wide normal limits.