Advanced Emphysema in African-American and White Patients: Demographic and Physiologic Racial Differences

Advanced Emphysema in African-American and White Patients: Demographic and Physiologic Racial DifferencesBetween 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 the study had a lower socioeconomic status and a lower level of education, and were less likely to be married (Fig 1).
Although the debut and duration of smoking was similar between the two races, African Americans smoked less both in terms of quantity of cigarettes and quality of exposure to cigarette smoke, ie, whites inhaled more deeply than African Americans (Table 2). this

When identical genders in each racial group were compared, African-American women were younger than white women, had comparable smoking profiles (Table 3), and were equally affected in terms of lung function (Fig 2), gas exchange, and exercise limitation (Fig 3). African-American men were also younger and physiologically similar to white men, except for the diffusion capacity of the lung for carbon monoxide (Figs 2, 3) but smoked less. Emphysema patients in both racial groups were similar with respect to receiving steroids (inhaled and oral; Table 1). The impact of emphysema on breathing and health-related quality of life was identical across races and genders; SGRQ and QWB scores were not different between the groups.
All 42 African-American patients were matched to white patients, but only 34 of the pairs had complete CT data that permitted extensive quantitative image analysis. No differences were found between the clinical characteristics of the two matched groups (Table 4). Taking the -950 HU as cutoff, African-American patients were found to have less severe emphysema based on whole-lung percentage of emphysema (7.0%, p = 0.01) and a value (Table 5); the difference in severity between the two ethnic groups was in both the core and the peel regions (9.2% and 4.6%, respectively; both p < 0.05). In both populations, regions of severe emphysema were more concentrated at the lung apex and lung core.

Table 1—Baseline Characteristics of Patients With Advanced Emphysema

Characteristics African American (n = 42) White (n = 1,156) p Value
Male gender 25 (60) 706(61) 0.87
Age, yr 62.8 ± 6.8 66.5 ± 6.1 0.0001
Body mass index, kg/m2 23.6 ± 3.1 24.8 ± 3.9 0.04
Height, cm 169 ± 9 169 ± 10 0.79
Use of oral steroids 13(31) 370 (32) 1.0
Use of inhaled steroids 28 (67) 806 (70) 0.73
FEVj, % predicted 27 ± 6 27 ± 7 0.92
FVC, % predicted 66 ± 15 5+ 17

6

0.76
TLC, % predicted 129 ± 15 129 ± 14 0.82
RV, % predicted 237 ± 47 225 ± 48 0.14
Pao2, mm Hg 66 ± 11 65 ± 10 0.59
Paco2, mm Hg 43 ± 5 43 ± 5 0.50
Maximal workload, W 33 ± 14 36 ± 21 0.14
Distance walked in 6 min, m 351 ± 93 347 ± 95 0.79
Average QWB score 0.55 ± 0.10 0.54 ± 0.12 0.35
Total SGRQ score 54 ± 13 57 ± 13 0.32

Table 2—Smoking Profiles of Patients With Advanced Emphysema

Variables African American (n = 42) White (n = 1,152)t p Value
Age started smoking, yr 17 ± 3 17 ± 4 0.39
Age quit smoking, yr 8+17

5

57 ± 8 0.72
Duration of smoking, yr 40 ± 8 42 ± 8 0.46
Average daily smoking, cigarettes/d 26 ± 14 32 ± 14 0.008
Inhalation of cigarette smoke Not at all 0 0.3 0.02
Slight 10 5
Moderate 55 36
Deep 36 59

Table 3—Race, Gender, Age, and Smoking Profiles

Patients No. Age, yr Smoking Debut, yr Duration, yr Age Quit, yr Amount, Cigarettes/d
African-American menT 25 63 ± 7 (p = 0.002) 17 ± 3 (p = 0.06) 41 ± 8 (p = 0.40) 57 ± 8 (p > 0.9) 27 ± 14 (p = 0.005)
White men 706 67 ± 6 16 ± 4 42 ± 9 58 ± 8 35 ± 14
African-American womenT 17 62 ± 7 (p = 0.02) 17 ± 4 (p > 0.9) 41 ± 8 (p > 0.9) 57 ± 8 (p = 0.63) 26 ± 14 (p = 0.48)
White women 450 66 ± 6 18 ± 4 41 ± 7 57 ± 7 28 ± 12

Table 4—Characteristics of Matched Patients for Quantitative CT Analysis

Characteristics African American (n = 34) White(n = 34)
Male genderf 19 (56) 19 (56)
Age, yrf 62 ± 7 63 ± 7
Height, cmf 169 ± 9 169 ± 9
FEVb % predicted 27 ± 6 25 ± 6
FVC, % predicted 66 ± 15 63 ± 16
TLC, % predicted 130 ± 16 132 ± 15
Age started smoking, yrf 17 ± 3 16 ± 3
Duration of smoking, yr 41 ± 8 7+ 10

4

Average daily smoking, cigarettes/df 26 ± 14 28 ± 11

Table 5—Quantitative CT Analysis at the — 950 HU Cutoff (Matched-Pairs Analysis)

Variables African American (n = 34) White(n = 34) p Value
Whole-lung emphysema 13.8 20.8 0.01
Whole lung af 1.09 0.95 0.01
Core emphysema 18.3 27.5 0.01
Peel emphysema 10.1 14.7 0.03
Upper — lower difference
Whole lung 9.6 16.3 0.15
Core — peel difference
Whole lung 8.2 12.9 0.02
Apical lung 12.8 18.3 0.02
Middle lung 7.5 10.9 0.08
Basal lung 6.7 9.5 0.25

Figure-1

Figure 1. Socioeconomic and education profiles by race. African-American patients had a lower level of education, lower income, and were less likely to be married. p = 0.01 for level of education; p = 0.01 for income; p < 0.001 for marital status. *Income is expressed X $1,000 (white patients, n = 1,145; African-American patients, n = 41 for income).

Figure-2

Figure 2. Race-, gender-, and age-adjusted pulmonary function test results. Similar genders were comparable in term of function, but diffusion limitation tended to be worse in both African-American genders compared to their white counterparts. *p = 0.002 between men (white patients, n = 1,145; African-American patients, n = 41 for income). Dlco = diffusion capacity of the lung for carbon monoxide.

Figure-3

Figure 3. Race, gender, gas exchange, and exercise function. Similar genders were not different between each other. Max = maximum.

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