Symptomatic smokers without COPD have physiological changes heralding the development of COPD

Area of Science:

• Pulmonary Medicine
• Respiratory Physiology
• Smoking-Related Diseases

Background:

• Chronic Obstructive Pulmonary Disease (COPD) is a significant global health issue, primarily linked to cigarette smoking.
• Current research often focuses on advanced COPD in older individuals, overlooking the early stages that begin soon after smoking initiation.
• There is a critical need for methods to diagnose early-stage COPD by identifying the initial pathological changes in smokers.

Purpose of the Study:

• To investigate if abnormal maximum mid expiratory flow (MMEF) in smokers without COPD (noCOPD) correlates with respiratory symptoms.
• To determine if MMEF can identify smokers at risk of progressing to COPD.
• To assess the relationship between MMEF, diffusing capacity of the lung for carbon monoxide (DLCO), and functional decline over time.

Main Methods:

• A cohort of 511 smokers (302 with COPD, 209 noCOPD) underwent long-term follow-up with spirometry, including MMEF and DLCO measurements.
• Functional assessments included the 6-minute walk test (6MWT), Medical Research Council Dyspnoea Scale, and COPD Assessment Test.
• Three spirometry sessions (V1, V2, V3) were conducted over approximately 10 years to evaluate functional decline and COPD development.

Main Results:

• 65% of noCOPD individuals exhibited abnormal MMEF (<80%), and 38% had abnormal DLCO.
• Smokers with abnormal MMEF showed worse 6MWT performance, increased dyspnea, and a higher prevalence of chronic bronchitis compared to those with normal MMEF.
• A significantly higher proportion of noCOPD individuals with abnormal MMEF (21%) developed COPD by V3 compared to those with normal MMEF (2.7%).

Conclusions:

• Maximum mid expiratory flow (MMEF), a standard spirometry measurement, effectively detects early lung abnormalities in smokers.
• Abnormal MMEF identifies symptomatic smokers with pathological changes indicative of future COPD development.
• Routine MMEF measurement can aid in the early diagnosis and management of individuals at risk for COPD.