Differences between FEV6, FVC and VC at the diagnosis of obstructive ventilatory defect.

Area of Science:

• Pulmonary Medicine
• Diagnostic Spirometry

Background:

• Diagnosing airway obstruction typically uses FEV1/FVC < 0.7 or FEV1/VC < LLN.
• FEV1/FEV6 ratio is proposed as an alternative diagnostic marker for obstructive ventilatory defect.

Purpose of the Study:

• To assess the non-inferiority of FEV1/FEV6 < 0.73 compared to FEV1/FVC < 0.7 and FEV1/VC < LLN for diagnosing airway obstruction.

Main Methods:

• Retrospective analysis of spirometry/plethysmography records from 2018.
• Included patients with FEV1/FVC < 0.7 or FEV1/VC < LLN.
• Compared these results with the FEV1/FEV6 ratio.

Main Results:

• FEV1/FEV6 ratio showed high positive predictive values (99.6% vs. FEV1/FVC, 91.0% vs. FEV1/VC) and diagnostic efficacy (92.8%, 85.2%).
• Non-inferiority was demonstrated, with false negatives primarily in mild obstruction cases (FEV1 > 70%) and older individuals (>50 years).

Conclusions:

• FEV1/FEV6 < 0.73 serves as a viable alternative for diagnosing obstructive ventilatory defect.
• The FEV1/FEV6 ratio is non-inferior to FEV1/VC and FEV1/FVC in clinical practice.