Impaired Ventilatory Efficiency as a Novel Indicator of Pre-COPD: A Prospective Cohort Study.

BACKGROUND

Accurately identifying pre-COPD is fundamental to delaying its onset and improving prognosis. Impaired ventilatory efficiency occurs in approximately 12% of individuals with preserved spirometry and is associated with severe lung damage; however, its value as an indicator of pre-COPD remains to be clarified.

RESEARCH QUESTION: Can impaired ventilatory efficiency serve as an indicator of pre-COPD in individuals with preserved spirometry?

STUDY DESIGN AND

METHODS

This 3-year prospective cohort study was conducted from July 2019 to September 2024. Eligible participants completed questionnaires, spirometry, and cardiopulmonary exercise testing at baseline and were followed up annually. Participants with preserved spirometry were included. Impaired ventilatory efficiency was defined as a nadir ventilatory equivalent for CO2 production > the upper limit of normal. The outcomes included the risk of COPD and annual lung function decline.

RESULTS

Overall, 573 participants were included, of whom 517 (90%) had at least 1 follow-up lung function measurement. Participants with impaired ventilatory efficiency (n = 92) had a significantly higher risk of spirometry-defined COPD (hazard ratio [HR], 2.31; 95% CI, 1.55-3.43; P < .001), clinically significant COPD (HR, 3.27; 95% CI, 1.81-5.91; P < .001), and moderate-to-very-severe COPD (HR, 3.73; 95% CI, 1.87-7.44; P < .001), and a faster annual decline in postbronchodilator FEV1 (adjusted mean difference, 16 mL/y; 95% CI, 0-32; adjusted P = .045) than participants with normal ventilatory efficiency.

INTERPRETATION: Our results show that impaired ventilatory efficiency is a potential indicator for pre-COPD.