Spirometry parameters used to define small airways obstruction in population-based studies: systematic review

Area of Science:

• Pulmonary Medicine
• Respiratory Physiology

Background:

• Spirometry is used in population studies to assess small airways obstruction (SAO).
• Current methods lack standardized parameters and criteria for defining abnormal SAO results.

Purpose of the Study:

• To systematically review population-based studies using spirometry to identify SAO.
• To determine the most common spirometry parameters and criteria for defining SAO.
• To extract prevalence estimates and identify associated risk factors for SAO.

Main Methods:

• Systematic literature search of Medline, Web of Science, and Google Scholar for studies published by May 1, 2021.
• Review of 25 studies that used spirometry to identify SAO.
• Meta-analysis to estimate pooled prevalence, with meta-regression to explore heterogeneity.

Main Results:

• FEF25-75 was the most utilized parameter (15 studies).
• Percent predicted cut-offs were the most common criteria (5 studies), but lacked consensus.
• SAO prevalence varied widely (7.5%–45.9%) with high heterogeneity (I²=99.3%).

Conclusions:

• A lack of consensus exists on the optimal spirometry parameter and criteria for SAO identification.
• The clinical utility of spirometry for SAO assessment remains uncertain pending further research.
• Large-scale longitudinal data are needed to clarify the value of SAO measurement.