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Parameter D: New Measure of Airflow Obstruction
Surya P Bhatt1,2,3, Arie Nakhmani1,4, Nithin M Thimmegowda1,2,3
1UAB Lung Imaging Lab.
Annals of the American Thoracic Society
|March 29, 2023
Summary
A new spirometry metric, Parameter D, aids in early airflow obstruction detection, unaffected by age. This method identifies more individuals with lung disease and symptoms, improving chronic obstructive pulmonary disease (COPD) diagnosis.
Area of Science:
- Pulmonary Medicine
- Respiratory Physiology
- Diagnostic Biomarkers
Background:
- Current spirometry measures for airflow obstruction are influenced by demographics, particularly age, complicating diagnostic threshold selection.
- There is a need for a more robust metric for airflow obstruction detection that is less susceptible to demographic variations.
Purpose of the Study:
- To develop and validate diagnostic thresholds for Parameter D, a novel metric quantifying the rate of rise of expiratory volume over time.
- To assess the performance of Parameter D in identifying individuals with airflow obstruction compared to traditional spirometry metrics.
Main Methods:
- Analysis of spirometry data from NHANES and UK Biobank cohorts to calculate Parameter D and assess demographic influences.
- Development of a population-based diagnostic threshold for Parameter D.
- Comparison of airflow obstruction classification using Parameter D versus FEV1/FVC lower limit of normal (LLN), and association with clinical outcomes.
Main Results:
- Demographics explained only 9% of variance in Parameter D, compared to traditional spirometry measures.
- A Parameter D threshold identified an additional 10.8% of participants with airflow obstruction in the COPDGene cohort.
- Individuals identified by Parameter D (D+COPD) exhibited worse structural lung disease, more symptoms, increased exacerbations, and higher mortality risk.
Conclusions:
- Parameter D is a novel spirometry metric for airflow obstruction detection that is independent of age.
- A population-based threshold for Parameter D enables earlier identification of individuals with airflow obstruction, structural lung disease, and symptoms.
- Parameter D offers a promising tool for improving the early diagnosis and management of chronic obstructive pulmonary disease (COPD).
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