Difference in Airflow Obstruction between Hispanic and Non-Hispanic White Female Smokers

Figures & data

Table 1 Distribution of potential risk factors for airflow obstruction among Hispanic and non-Hispanic White (NHW) female smokers

Characteristics		Hispanic (n = 248)	NHW (n = 1,185)	p-value
Age (in years)	Mean (S.D.)	53.6 (8.9)	56.5 (9.5)	< 0.001
Body mass index (BMI) category	BMI < 25 kg/m^2 – Normal or Underweight (%)^♣	28.2	37.2	0.03
	BMI 25 to < 30 kg/m^2 – Overweight (%)	39.1	34.0
	BMI ≥ 30 kg/m^2 – Obese (%)	32.7	28.8
Education (% > high school)^†		47.0	73.3	< 0.001
Annual income (% > $40,000)^‡		33.2	41.2	0.04
Current smokers (%)		78.6	53.6	< 0.001
Pack-years of smoking	Median (25th, 75th percentiles)	29.0 (21.9, 38.3)	35.0 (26.0, 49.5)	< 0.001
Duration of smoking (in years)	Mean (S.D.)	33.5 (8.8)	33.3 (9.9)	0.85
Age of start of smoking (in years)	Mean (S.D.)	16.9 (4.0)	17.1 (3.8)	0.41
Time since smoking cessation for ex-smokers (in years)	Mean (S.D.)	9.2 (6.8)	10.6 (8.8)	0.17

^†113 participants had missing data on education.

^‡289 participants had missing data on income.

*1 participant had missing data on duration and pack-years of smoking.

^♣: 25/1,433 (1.7%) subjects were underweight (BMI < 18 kg/m²).

Table 2 Distribution of pulmonary function test and chronic mucus hyper-secretion variables among Hispanic and non-Hispanic White (NHW) female smokers

Outcomes		Hispanic (n = 248)	NHW (n = 1,185)	p-value
FEV1 percent predicted	Mean (S.D.)	90.8 (16.5)	86.3 (18.7)	< 0.001
FEV1 absolute (liters)	Mean (S.D.)	2.35 (0.57)	2.32 (0.63)	0.49
FEV1/FVC percent predicted	Mean (S.D.)	80.3 (2.0)	78.8 (2.0)	< 0.001
FEV1/FVC absolute	Mean (S.D.)	77.5 (7.8)	73.3 (12.3)	< 0.001
Airflow obstruction (%) Irreversible airflow obstruction, for those with obstruction (%)		12.9	24.2	< 0.001
		87.5	89.9	0.76
Airflow obstruction, using < 70% FEV1/FVC ratio criterion (%) Irreversible airflow obstruction, for those with obstruction, using < 70% FEV1/FVC ratio criterion (%)	11.7	28.1	< 0.001
	89.6	84.6	0.50
Severity of lung impairment among those with airflow obstruction (%)	Stage 1	40.6	25.1	0.17
	Stage 2	43.8	56.1
	Stages 3 & 4	15.6	18.8
Severity of lung impairment among those with airflow obstruction, using < 70% FEV1/FVC ratio criterion (%)	Stage 1	30.9	34.5	0.89
	Stage 2	52.9	48.3
	Stages 3 & 4	16.2	17.2
Chronic mucus hyper-secretion (%)		40.4	32.1	0.01
Chronic mucus hyper-secretion or airflow obstruction (%)		45.7	46.6	0.80
Chronic mucus hyper-secretion or airflow obstruction, using < 70% FEV1/FVC ratio criterion (%)	44.5	48.8	0.22

*Distribution of absolute FEV₁ among the ethnic groups is shown in Figure 2.

Table 3 Odds ratios for airflow obstruction and chronic mucus hyper-secretion for Hispanic (n = 248) relative to non-Hispanic White (n = 1,185) female smokers

	Unadjusted analysis			Adjusted analysis^†
Outcomes	Odds Ratio	95% C.I.	p-value	Odds Ratio	95% C.I.	p-value
Airflow obstruction	0.46	0.31, 0.69	< 0.001	0.51	0.34, 0.78	0.002
Airflow obstruction (using < 70% FEV1/FVC ratio criterion)	0.34	0.22, 0.50	< 0.001	0.37	0.24, 0.58	< 0.001
Chronic mucus hyper-secretion	1.44	1.08, 1.91	0.01	1.13	0.83, 1.54	0.43
Chronic mucus hyper-secretion or airflow obstruction	0.96	0.73, 1.27	0.80	0.85	0.63, 1.14	0.28

^†Adjusted for age, BMI category, pack-years and duration of smoking, and current smoking status. Similar results were obtained when time since smoking cessation was included in the model instead of duration of smoking.

Note: For Chronic mucus hyper-secretion, the ethnicity effect is no longer significant after current smoking status is added to the model.

Figure 1 Distribution of airflow obstruction and ethnicity in the cohort.

Figure 2 Boxplot showing the distribution of absolute values of FEV₁ among the ethnic groups, among all participants and those with airflow obstruction, as defined by NHANES-III fifth percentile of FEV₁/FVC ratio.

For comparison of NHW and Hispanics, unadjusted for other covariates and using the Kruskal-Wallis test: p = 0.65 (all participants) and p = 0.41 (participants with airflow obstruction).

Table 4 Differences in least squares means of selected pulmonary function parameters between Hispanic (n = 248) and non-Hispanic white (n = 1,185) female smokers

	Unadjusted analysis			Adjusted analysis^‡
Outcomes	Difference (NHW – Hispanic)	95% C.I.	p-value	Difference (NHW – Hispanic)	95% C.I.	p-value
Mean percent predicted FEV1	−4.51	−7.02, −1.99	< 0.001	−2.74	−0.30, 5.18	0.03
Mean absolute FEV1(in liters)	−0.03	−0.11, 0.06	0.52	−0.05	−0.11, 0.02	0.13
Mean percent predicted FEV1/FVC ratio 100	−1.51	−1.78, −1.23	< 0.001	−0.89	−0.89, −0.88	< 0.001
Mean absolute FEV1/FVC ratio 100	−4.21	−5.81, −2.62	< 0.001	−2.78	−4.34, −1.21	< 0.001

^‡Adjusted for age, BMI category, pack-years and duration of smoking, and current smoking status. Additionally, absolute lung function values were adjusted for height (similar results were obtained when height² was added to the model). Similar results were obtained when time since smoking cessation was included in the model instead of duration of smoking.

*There was a significant interaction between ethnicity and current smoking status in modeling percent predicted FEV₁/FVC ratio; p < 0.001. The adjusted difference in mean percent predicted FEV₁/FVC ratio between non-Hispanic Whites (NHW) and Hispanics in current smokers was −0.90% (−0.91, −0.897%) and in ex-smokers was −0.84% (−0.85, −0.83).