FEV1 decline varies widely in COPD, another cohort confirms (AJRCCM)

COPD is frequently referred to as progressive and terminal, undoubtedly contributing to the anxiety and depression COPD patients commonly experience. It’s true that COPD is a leading cause of death. But as study after study shows, it appears the universal “progressive” descriptor is an oversimplification, and that optimism and hope are just as realistic as doomsaying when counseling patients with COPD.

For starters, a longitudinal cohort study in the New England Journal recently showed that among people with chronic obstructive pulmonary disease, the rate of FEV1 decline varies widely. In about half, in fact, FEV1 declined no faster than the expected rate in lifelong nonsmokers. Another recent cohort study in the Blue Journal likewise showed considerable heterogeneity in FEV1 decline among COPD patients. The findings upset the conventional wisdom of emphysema as consisting of progressive loss of lung function even after smoking cessation.

Masaharu Nishimura et al add to the growing awareness of the complexity of COPD, with their own longitudinal cohort study in the January Blue Journal. (Apparently, this is a hot area right now.)

They followed 279 Japanese patients with COPD for 5 years, collecting pulmonary function testing and CT scans every 6-12 months. (Their baseline findings on this cohort, reported in Thorax in 2007, were interesting in that they showed that anatomic emphysema on CT scan is poorly correlated with airflow limitation (i.e., spirometric “stage” of COPD), and that chronic bronchitis symptoms were evenly distributed among patients. The net finding: most patients defy categorization by COPD phenotype.)

After completing 4-5 years follow-up on 82% of the survivors of the original cohort, they were able to categorize lung function decline as follows:

• Rapid Decliners (<25th percentile): FEV1 loss of 63 mL/year (65 patients)
• Slow Decliners (25-75th percentile): FEV1 loss of 31 mL/year (130 patients)
• Sustainers (>75th percentile): FEV loss of 2 mL/year (65 patients)

What predicted Rapid Decline? Only BMI, which was relatively lower in the rapid decliners, and emphysema severity on CT scan, higher in the rapid decliners. (Spirometric stage at baseline, smoking history, continued smoking, and exacerbation frequency did not predict rate of decline.) Rapid decliners also had higher circulating eosinophil counts, for some reason.

Like the recent NEJM cohort, a substantial minority (here, ~25%) had essentially no loss of lung function over 5 years, a remarkable finding. Does this help explain the common anecdotal observation of physician surprise that people with COPD seem to “live forever”? Maybe the patients are living how long they’re supposed to, and we doctors just never had our facts straight.

Limitation: patients were all ethnically Japanese; Japanese patients had a ~30% lower rate of FEV1 decline than other races in the UPLIFT study, for unclear reasons.

Clinical Takeaway: It’s time to stop counseling patients who have quit smoking that COPD is a progressive and terminal disease. Many patients are under the impression that they are steadily dying of emphysema; unless it’s obvious that they are, physicians should re-educate them in light of the new findings in this and recent papers, which create space for optimism in the prognosis of COPD. Such a positive counseling approach might improve the mood, attitude and quality of life of people living with COPD (and — dare I hope? —  help them increase their activity levels).

Nishimura M et al. Annual Change in Pulmonary Function and Clinical Phenotype in Chronic Obstructive Pulmonary Disease. Am J Respir Crit Care Med 2012;185:44-52.