Spirometry alone isn’t sufficient to rule out lung disease in current and former smokers, according to an observational study in JAMA Internal Medicine.
Some 4400 chronic (current or former) smokers with normal spirometry findings, 800 with mild COPD on spirometry, and 100 never-smokers underwent chest computed tomography, a 6-minute walk test, and symptom questionnaires.
CT revealed emphysema or evidence of airway disease in 42% of smokers with normal spirometry, versus 10% of never-smokers (and 81% with mild COPD). The prevalence of lung damage increased with advancing age. In addition, smokers with normal spirometry had worse quality-of-life and performance on the 6-minute walk test than did never-smokers.
The authors conclude: “We project that there are 35 million current and former smokers older than 55 years in the United States who may have unrecognized disease or impairment. The effect of chronic smoking on the lungs and the individual is substantially underestimated when using spirometry alone.”