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Lung volume indices predict morbidity in smokers with preserved spirometry
Siyang Zeng1,2, Andrea Tham1,3, Bruce Bos1,4
1Medical Section, San Francisco Veterans Affairs Medical Center, San Francisco, California, USA.
Thorax
|July 22, 2018
Summary
Air trapping, a common lung issue in smokers with normal spirometry, is linked to worse respiratory outcomes and COPD progression. This finding highlights the importance of lung volume measurements in early disease detection.
Area of Science:
- Pulmonary Medicine
- Respiratory Health
- Clinical Research
Background:
- Abnormal lung volumes indicating air trapping are frequent in COPD patients.
- The clinical significance of air trapping in smokers with preserved spirometry (normal FEV1:FVC ratio) remains unclear.
Purpose of the Study:
- To investigate the prevalence and clinical significance of air trapping in smokers with preserved spirometry.
- To determine if air trapping predicts adverse respiratory outcomes and progression to COPD.
Main Methods:
- Utilized the Veterans Administration Informatics and Computing Infrastructure database to identify 7479 at-risk patients (smokers >40 years, no restrictive lung disease) with preserved spirometry.
- Analyzed subsequent health records for COPD diagnoses, healthcare utilization, follow-up spirometry, and mortality.
- Examined lung volume measurements, including residual volume to total lung capacity ratio (RV:TLC).
Main Results:
- Air trapping (RV:TLC > upper limit of normal) was prevalent in 31% of patients.
- Elevated RV:TLC was associated with increased likelihood of COPD diagnosis (HR=1.55), higher all-cause mortality (HR=1.41), and greater healthcare utilization.
- Abnormal RV:TLC predicted a higher likelihood of progression to spirometric COPD (OR=1.30).
Conclusions:
- Air trapping is common in smokers with preserved spirometry.
- It predicts adverse respiratory outcomes, including progression to overt COPD.
- Lung volume measurements are valuable for assessing risk in this population.
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