Background: Emphysema is the only smoking-related disease in which white patients have higher prevalence and higher attributable mortality rates than African-American patients. Epidemiologic studies have not addressed, nor explained, the observed racial differences in emphysema.
Study objectives: To determine whether white and African-American patients differ with respect to the magnitude, anatomic distribution, and physiologic impairments of emphysema.
Patients: Characteristics of patients with severe and very severe emphysema enrolled in the National Emphysema Treatment Trial were examined and compared. Patient demographics, cardiopulmonary function, quality of life, and severity/distribution of the emphysema by quantitative CT were analyzed.
Results: Of the 1,218 patients enrolled in the trial, 42 were African American (3.4%) and 1,156 were white (95%). African Americans were younger (mean age ± SD, 63 ± 7 years vs 67 ± 6 years) and smoked less (26 ± 14 cigarettes per day vs 32 ± 14 cigarettes per day) than white patients (p = 0.01). There was no difference between the two racial groups in pulmonary function (FEV1, 27 ± 6% predicted vs 27 ± 7% predicted), gas exchange (Pao2, 66 ± 11 mm Hg vs 65 ± 10 mm Hg), and exercise (33 ± 14 W vs 36 ± 21 W), respectively. Quality of life measures were similar between the groups, but African Americans had a lower socioeconomic status, lower education level, and fewer were married. Radiographic analysis of the extent of emphysema in African Americans, who were matched with selected white patients, revealed significantly less emphysema in the former group and different distribution of severe emphysema.
Conclusions: African Americans with emphysema were younger and had a similar degree of lung impairment as the white study population despite smoking less. In a subgroup of matched patients, the severity and distribution of emphysema by quantitative radiographic analysis were different.