Natural history of emphysema

Abstract

Chronic obstructive pulmonary disease (COPD) is a progressive disease with studies of disease progression generally focusing on measures of airflow and mortality. In nonsmokers, maximal lung function is attained around age 15 to 25 years, and after a variable plateau phase, subsequently declines at approximately 20 to 25 ml/year. Smoking may reduce the maximal FEV(1) achieved, shorten or eliminate the plateau phase, and may accelerate the rate of decline in lung function in a dose-dependent manner. Some smokers are predisposed to more rapid declines in lung function than others, and recent reports suggest that females may be at higher risk of lung damage related to smoke exposure than males. Progressive deterioration in dyspnea, functional status, and health-related quality of life (HRQL) in patients with COPD is well known, but the magnitude and rate of decline and its association with severity of airflow obstruction remains poorly defined. Many studies have identified pulmonary function, in particular the FEV(1), as the single best predictor of survival. An impaired diffusing capacity and overall impairment in functional status have also been associated with impaired survival in COPD. The National Emphysema Treatment Trial has provided additional insight into these features in a large, well-characterized group of patients with severe airflow obstruction and structural emphysema.

Figure 1.

Change from baseline in FEV₁% predicted in non–high-risk medically treated patients in the National Emphysema Treatment Trial (NETT) who completed the procedure after 6, 12, or 24 months of follow-up (Reprinted by permission from 48).

Figure 2.

(A) Change from baseline in maximal achieved six-minute walk test distance in non–high-risk medically managed patients in the NETT who completed the procedure after 6, 12, or 24 months of follow-up (48). (B) Longer-term change from baseline in maximal achieved watts during oxygen supplemented cardiopulmonary exercise testing in medically managed patients in the NETT (Reprinted by permission from 57).

Figure 2.

(A) Change from baseline in maximal achieved six-minute walk test distance in non–high-risk medically managed patients in the NETT who completed the procedure after 6, 12, or 24 months of follow-up (48). (B) Longer-term change from baseline in maximal achieved watts during oxygen supplemented cardiopulmonary exercise testing in medically managed patients in the NETT (Reprinted by permission from 57).

Figure 3.

Change from baseline in the University of California, San Diego Shortness of Breath Questionnaire (UCSD SOBQ) among non–high-risk, medically managed NETT patients (Reprinted by permission from 48). A minimal clinically important improvement is a decrease in UCSD SOBQ of 5 points or more.

Figure 4.

Change in St. George's Respiratory Questionnaire in all patients randomized to the medical arm of the NETT during 5 years of follow-up (Reprinted by permission from 57).

Figure 5.

Kaplan-Meier estimates of the probability of death as a function of number of years after randomization for medically treated patients segregated by age. The P value was derived by the log rank test for the comparison between subgroups over a median follow-up period of 3.9 years (Reprinted by permission from Reference 94).

Figure 6.

Kaplan-Meier estimates of the probability of death as a function of number of years after randomization for medically treated patients segregated by modified BODE index. The P value was derived by the log rank test for the comparison between subgroups over a median follow-up period of 3.9 years (Reprinted by permission from Reference 94).

Figure 7.

Kaplan Meier survival plot of the 101 cases of severe (Global Initiative for Chronic Obstructive Lung Disease [GOLD] stage 3) and very severe (GOLD stage 4) chronic obstructive pulmonary disease, indicating that median survival was shortened in the quartile with the most severe occlusion of the fully expanded lumen (HR [hazard ratio], 3.28; 95% confidence interval, 1.55 to 6.92; P = 0.002) (Reprinted by permission from Reference 95).