Chest
Original ResearchAdvanced Emphysema in African-American and White Patients: Do Differences Exist?
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Materials and Methods
The NETT is a multicenter, randomized clinical trial of optimal medical therapy vs optimal medical therapy plus lung volume reduction surgery in the treatment of severe emphysema. The design and methods of the NETT have been described previously and are summarized below.11 All analyzed data were obtained from the baseline prerehabilitation assessment during the first or second visit to NETT centers, except for some chest CT scans that were collected after rehabilitation.
Patient Selection
The inclusion criteria were as follows: FEV1 ≤ 45% of predicted value, and if age ≥ 70 years, FEV1 ≥ 15% of predicted; total lung capacity (TLC) ≥ 100% of predicted; residual volume (RV) ≥ 150% of predicted; Paco2 ≤ 60 mm Hg (≤ 55 mm Hg in Denver), with patients at rest and breathing room air; Pao2 ≥ 45 mm Hg (≥ 30 mm Hg in Denver), with patients at rest and breathing room air; ability to walk > 140 m (459 feet) in 6 min; ability to complete 3 min of pedaling on a bicycle ergometer without a
Patient Data
The initial evaluation included 6-min walk distance15; postbronchodilator pulmonary function tests; maximal exercise capacity during cycle ergometry while receiving 30% oxygen; echocardiography; radionuclide pharmacologic (dobutamine) cardiac stress testing; arterial blood gas measurement; and lung perfusion scanning. Patients also responded to a battery of general and disease-specific self- administered quality of life scales16: the Quality of Well-being (QWB) scale, the Short Form-36, St.
Diagnostic Imaging Studies
The severity and distribution of emphysema were determined from CT scans of the chest obtained during full inspiration. Spiral CT scans were acquired with a collimation ranging from 3 to 10 mm, with the majority of the centers having a slice collimation ≤ 5 mm. Data were evaluated using the standard reconstruction kernel but were not complete for all patients because of early archiving problems, not meeting a set of minimum criteria for matching the prescribed scanning protocol, or missing
Statistical Analysis
Categorical variables were compared using χ2 and Fisher Exact Test. Continuous variables (age, FEV1, TLC, RV) were compared using two-way analysis of variance to evaluate differences between gender and race, and multiple pair-wise comparisons used the Dunn-Bonferroni adjustment to maintain an experiment-wise type I error ≤ 0.05. Prior to analysis, continuous data were tested for normality using the Shapiro-Wilk test. If the data for the continuous dependent variables were significantly
Demographic and Physiologic Racial Differences
Between January 1998 and July 2002, a total of 1,218 patients with severe emphysema were enrolled in the NETT. Forty-two of the patients (3.4%) were African American, and 1,156 patients (95%) were white. The baseline characteristics of these patients are shown in Table 1. African Americans were younger and less heavy. There was no difference in the severity of the emphysema based on static pulmonary function, gas exchange, exercise performance, and use of steroids. African-American patients in
Discussion
Our data show that African-American patients with advanced emphysema presented with impairment comparable to white patients as identified by lung function, exercise, and quality of life measures, and at a younger age despite smoking less. Each gender within the two racial groups was as affected as its counterpart; African-American women were not less severely sick than white women. However, when matched with respect to age, height, smoking, and pulmonary function, African-American patients
Source of Funding
The NETT is supported by contracts with the National Heart, Lung, and Blood Institute (N01HR76101, N01HR76102, N01HR76103, N01HR76104, N01HR76105, N01HR76106, N01HR76107, N01HR76108, N01HR76109, N01HR76110, N01HR76111, N01HR76112, N01HR76113, N01HR76114, N01HR76115, N01HR76116, N01HR76118, and N01HR76119), the Centers for Medicare and Medicaid Services (formerly the Health Care Financing Administration); and the Agency for Healthcare Research and Quality.
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University of Pennsylvania,
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Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/misc/reprints.shtml).
Details of National Emphysema Treatment Trial membership and locations are given in the Appendix.
Dr. Hoffman is a shareholder of VIDA Diagnostics, which seeks to commercialize the software that may be relevant to this article.