Racial and Ethnic Minorities Have a Lower Prevalence of Airflow Obstruction than Non-Hispanic Whites

Figures & data

Table 1. Descriptive racial and ethnic differences in demographic and exposure characteristics in the three cohorts.

	COPDGene Study		LSC		MiDUS Cohort
	African-American (n = 3,416)		Hispanic (n = 378)		Hispanic (n = 2,682)
Characteristic	Mean ± SD or % NHW (n = 6,884)		Mean ± SD or % NHW (n = 1,598)		American Indian Mean ± SD or %   (n = 2,467) NHW(n = 2,115)
Age (years)	54.6 ± 7.2	62.0 ± 8.9*	53.3 ± 8.9	56.2 ± 9.5*	52.2 ± 14.3	58.8 ± 11.8	53.7 ± 16.0*
Men	55.2%	52.3%*	25.7%	22.6%	96.6%	93.4%	95.4%*
Height (cm)	171.0 ± 9.7	169.7 ± 9.5**	162.5 ± 8.1	166.8 ± 8.6**	168.8 ± 7.0	168.6 ± 7.1	174.5 ± 7.7*
Weight (kg)	84.9 ± 19.9	82.8 ± 19.5*	75.9 ± 17.0	78.0 ± 18.9 *	82.6 ± 16.4	82.1 ± 15.8	87.6 ± 17.0*
BMI (kg/m^2)	29.1 ± 6.7	28.7 ± 6.0	28.7 ± 6.0	28.0 ± 6.2*	28.9 ± 5.1	28.9 ± 5.1	28.7 ± 5.1
Current smoking	80.0%	38.9%*	13.0%	10.1%	23.7%	7.5%	22.1%*
Pack-years of smoking	38.3 ± 21.6	47.2 ± 26.0*	33.1 ± 15.4	40.9 ± 21.4*	10.6 ± 18.5	2.8 ± 11.5	17.1 ± 24.1*
≥High school education	74.7%	92.2%*	45.5%	75.2%*	42.0%	29.4%	62.3%*
Total mining tenure (in years)					12.9 ± 11.9	8.8 ± 9.8	13.6 ± 14.0*
Self-reported exposure to dust or fumes	61.3%	58.0%*	37.0%	33.5%

Note: **p < 0.05, *p < 0.01; for the MiDUS Cohort, the p values refer to three-group comparison; non-parametric tests (Wilcoxon rank-sum) were used for continuous variables, and chi-square test was used for categorical variables.

Abbreviations: COPD, chronic obstructive pulmonary disease; LSC, Lovelace Smokers’ Cohort; MiDUS, Mining Dust Exposure in the United States.

Table 2. Univariate analysis of racial and ethnic differences in respiratory outcomes in the three cohorts.

	COPDGene Study		LSC		MiDUS Cohort
Respiratory outcome	African-American (n = 3,416)		Hispanic (n = 378)		Hispanic (n = 2,682)
	Mean ± SD or % NHW (n = 6,884)		Mean ± SD or % NHW (n = 1,598)		American Indian Mean ± SD or %   (n = 2,467) NHW(n = 2,115)
Airflow obstruction (GOLD definition FEV1/FVC < 70%)	35.7%	55.5%*	14.8%	32.7%*	13.3%	15.1%	26.3%*
Airflow obstruction (FEV1/FVC < LLN (or z score −1.645)) NHANES III	28.9%	43.1%*	16.1%	26.5%*	11.1%	7.1%	18.7%*
Airflow obstruction (FEV1/FVC < LLN (or z score −1.645)) GLI	27.01%	41.68%*	10.85%	24.23%*	8.3%	6.7%	17.5%*
Absolute FVC (Ls.)	3.1 ± 0.9	3.4 ± 1.0*	3.4 ± 0.9	3.5 ± 0.9	4.3 ± 1.0	4.0 ± 0.9	4.6 ± 1.1*
FVC z score, NHANES III	−0.73 ± 1.26	−1.10 ± 1.43 *	−0.34 ± 1.17	−0.54 ± 1.21*	−0.10 ± 1.49	0.02 ± 1.42	−0.33 ± 1.33*
FVC z score, GLI	−0.75 ± 1.22	−0.76 ± 1.25	−0.3 ± 1.05	−0.29 ± 1.06	0.05 ± 1.22	−0.16 ± 1.15	0.03 ± 1.27*
Absolute FEV1 (Ls.)	2.3 ± 0.9	2.2 ± 1.0*	2.6 ± 0.7	2.5 ± 0.8	3.3 ± 0.9	3.1 ± 0.8	3.4 ± 1.0*
FEV1 z score, NHANES III	−1.09 ± 1.44	−1.82 ± 1.82 *	−0.60 ± 1.27	−0.97 ± 1.34*	−0.11 ± 1.41	−0.21 ± 1.30	−0.41 ± 1.57*
FEV1 z score, GLI	−1.13 ± 1.41	−1.57 ± 1.60 *	−0.53 ± 1.18	−0.82 ± 1.23*	−0.10 ± 1.26	−0.25 ± 1.18	−0.37 ± 1.39*
FEV1/FVC ratio absolute	72.0 ± 13.8	64.3 ± 16.6*	76.6 ± 9.0	72.3 ± 10.6*	77.4 ± 9.7	76.9 ± 8.3	73.2 ± 10.7*
Ratio z score, NHANES III	−1.22 ± 2.08	−2.04 ± 2.72 *	−0.59 ± 1.52	−1.02 ± 1.67*	−0.21 ± 1.67	0.14 ± 1.34	−0.64 ± 1.67*
Ratio z score, GLI	−0.90 ± 1.61	−1.57 ± 1.74 *	−0.43 ± 1.1	−0.92 ± 1.22*	−0.22 ± 1.97	−0.16 ± 1.05	−0.71 ± 1.23*
Self-reported physician diagnosis of COPD	11.6%	19.0%*	7.7%	13.4%*	7.3%	11.5%	13.7%*
Chronic bronchitis^a	15.7%	20.6%*	27.2%	24.8%	16.8%	15.7%	18.4*
mMRC score	1.5 ± 1.5	1.3 ± 1.4*	2.1 ± 1.4	1.7 ± 1.4*	1.3 ± 1.5	2.2 ± 1.6	1.0 ± 1.3*
Score 0	42.3%	45.9%*	19.0%	23.2%	41.9%	26.2%	46.8%
Score 1	11.6%	14.8%*	23.3%	32.1%*	10.6%	7.9%	17.5%
Score 2	13.5%	12.6%	2.4%	2.0%	9.8%	10.5%	10.5%
Score 3	20.2%	17.5%*	42.3%	33.9%*	10.3%	17.0%	8.0%
Score 4	12.4%	9.0%*	13.0%	8.8%	10.8%	29.5%	7.8%
Prevalent self-reported cardiovascular disease	7.6%	12.5%*	26.7%	34.7%*	14.4%	33.2%	17.9%*

Note: **p < 0.05, *p < 0.01; for the MiDUS cohort, the p values refer to three-group comparison; non-parametric tests (Wilcoxon rank-sum) were used for continuous variables, and chi-square test was used for categorical variables.

Abbreviations : COPD, chronic obstructive pulmonary disease; FVC, forced vital capacity; FEV1, Forced expiratory volume in one second; GLI, Global Lung Initiative; GOLD, Global Obstructive Lung Disease; LSC, Lovelace Smokers’ Cohort; MiDUS, Mining Dust Exposure in the United States; mMRC, Modified Medical Research Council; NHANES, National Health and Nutrition Examination Survey.

a Standard definition of chronic bronchitis was defined by cough and phlegm production for at least three months a year for two or more consecutive years.

Table 3. Multivariable analysis of racial and ethnic differences in respiratory outcomes in the three cohorts.

Respiratory outcomes	COPDGene Study-African American	LSC-Hispanic	MiDUS Cohort-Hispanic	MiDUS Cohort-American Indian
Categorical outcomes	Odds ratio (95% CI)	Odds ratio (95% CI)	Odds ratio (95% CI)	Odds ratio (95% CI)
Airflow obstruction (GOLD definition FEV1/FVC < 70%)	0.72 (0.65, 0.80)*	0.45 (0.31, 0.65)*	0.50 (0.32, 0.78)*	0.29 (0.18, 0.48)*
Airflow obstruction (FEV1/FVC < LLN (or z score −1.645)), NHANES III	0.85 (0.76, 0.94)*	0.64 (0.45, 0.91)*	0.59 (0.50, 0.71)*	0.47 (0.37, 0.59)*
Airflow obstruction (FEV1/FVC < LLN (or z score −1.645)), GLI	0.80 (0.72,0.89)*	0.44 (0.27, 0.69)*	0.47 (0.39, 0.57)*	0.50 (0.39, 0.62)*
Self-reported physician diagnosis of COPD	0.56 (0.49, 0.65)*	0.79 (0.48, 1.24)	0.52 (0.26, 1.06)	0.38 (0.19, 0.75)*
Chronic bronchitis^a	0.50 (0.44, 0.56)*	0.87 (0.63, 1.18)	1.42 (0.92, 2.19)	1.36 (0.88, 2.12)
mMRC score <2	0.61 (0.55, 0.67) *	0.59(0.45, 0.78)*	0.68 (0.59, 0.80)*	0.34 (0.29, 0.40)*
mMRC score ≥ 2	1.65 (1.49, 1.82)*	1.69 (1.28, 2.23)*	1.33 (1.15, 1.53)*	3.33 (2.85, 3.88)*
Continuous outcomes	Difference (95% CI)	Difference (95% CI)	Difference (95% CI)	Difference (95% CI)
FVC z score, NHANES III	0.25 (0.19, 0.32)*	0.15 (0.00, 0.30)**	0.09 (−0.02, 0.19)	−0.19 (−0.30, −0.07)*
FVC z score, GLI	−0.06 (−0.12, −0.01)	−0.04 (−0.18, 0.11)	−0.01 (−0.01, 0.08)	−0.15 (−0.25, −0.05)*
FEV1 z score, NHANES III	0.43 (0.36, 0.51) *	0.26 (0.09, 0.42) *	0.23 (0.12, 0.33)*	0.05 (−0.06, 0.17)
FEV1 z score, GLI	0.18 (0.11, 0.25) *	0.17 (0.01, 0.34)**	0.21 (0.11, 0.30)*	0.02 (−0.08, 0.13)
FEV1/FVC ratio z score, NHANES III	0.15 ± (0.04, 0.26)*	0.28 (0.08, 0.48)*	0.33 (0.21, 0.45)*	0.44 (0.31, 0.57)*
FEV1/FVC ratio z score, GLI	0.23 (0.16, 0.31) *	0.34 (0.18, 0.50)*	0.41 (0.30, 0.53)*	0.31 (0.19, 0.44)*
mMRC (mean)	0.33 (0.26, 0.39)*	0.27 (0.10, 0.43)*	0.17 (0.06, 0.28)*	0.76 (0.64, 0.88)*

Note: NHWs served as the referent group for separate comparisons in each cohort without pooling data across cohorts. All analyses were adjusted for age, baseline BMI, and pack-years of smoking as continuous variables, as well as high school education, sex, and current smoking status at baseline as categorical variables. In addition, total mining tenure was included as a continuous covariate in the MiDUS cohort and exposure to dust and fumes as a categorical covariate in the other two cohorts. **p < 0.05, *p < 0.01. Categorical mMRC scores were analyzed using logistic regression. For the mean of continuous mMRC score in the LSC, Hispanics showed a p-value of 0.07.

Abbreviations: COPD, chronic obstructive pulmonary disease; FVC, forced vital capacity; FEV1, forced expiratory volume in one second; GLI, Global Lung Initiative; GOLD, Global Obstructive Lung Disease; LSC, Lovelace Smokers’ Cohort; MiDUS, Mining Dust Exposure in the United States; NHANES, National Health and Nutrition Examination Survey.

a Standard definition of chronic bronchitis was defined by cough and phlegm production for at least three months a year for two or more consecutive years.

Table 4. Multivariable analysis of racial and ethnic differences in mMRC dyspnea score in the three cohorts, with NHWs as the referent group in each cohort, after additional adjustment for spirometric pattern and self-reported cardiovascular disease.

	COPDGene Study-African American	LSC-Hispanic	MiDUS Cohort-Hispanic	MiDUS Cohort-American Indian
Categorical outcomes	Odds ratio (95% CI)	Odds ratio (95% CI)	Odds ratio (95% CI)	Odds ratio (95% CI)
mMRC < 2	0.50 (0.45, 0.56)*	0.52 (0.39, 0.69)*	0.65 (0.55, 0.76)*	0.36 (0.30, 0.42)*
mMRC ≥ 2	1.99 (1.78, 2.22)*	1.93 (1.45, 2.58)*	1.36 (1.17, 1.58)*	3.14 (2.68, 3.68)*
Continuous outcomes	Difference (95% CI)	Difference (95% CI)	Difference (95% CI)	Difference (95% CI)
mMRC (mean)	0.40 (0.34, 0.46)*	0.33 (0.17, 0.49)*	0.21 (0.10, 0.32)*	0.71 (0.59, 0.83)*

Note: The analyses were adjusted for age, baseline BMI, total mining tenure, and pack-years of smoking as continuous variables, as well as high school education, sex, current smoking status, spirometric patterns (restrictive or obstructive), and cardiovascular disease at baseline as categorical variables. In addition, total mining tenure was included as a continuous covariate in the MiDUS cohort and exposure to dust and fumes as a categorical covariate in the other two cohorts. **p < 0.05, *p < 0.01.

Abbreviations: COPD, chronic obstructive pulmonary disease; LSC, Lovelace Smokers’ Cohort; MiDUS, Mining Dust Exposure in the United States; mMRC, Modified Medical Research Council.