Table 3.

Select predictors of higher productive cough severity states, using multivariable ordinal logistic regression for the Lovelace Smokers’ Cohort (LSC) and the COPDGene Cohort.

Statistical Models	Predictor variable	LSC OR (95% CI)	p value	COPDGene OR (95% CI)	p value
Model 1	Age (in years)	1.01 (0.99, 1.02)	0.3	1.02 (1.01, 1.03)	<0.001
	Male sex	1.78 (1.38, 2.3)	<0.001	1.11 (0.97, 1.26)	0.13
	African American race	-	-	0.58 (0.5, 0.67)	<0.001
	Hispanic ethnicity	0.77 (0.58, 1.12)	0.25	-	-
	Obese	1.02 (0.8, 1.31)	0.88	1.05 (0.92,1.19)	0.48
	Pack-years/10	1.12 (1.05, 1.19)	<0.001	1.18 (1.15, 1.22)	<0.001
	Current smoker	5 (3.82, 6.54)	<0.001	4.19 (3.58, 4.91)	<0.001
	Dust and fume exposure	1.99 (1.58, 2.52)	<0.001	1.69 (1.48, 1.92)	<0.001
	Hypertension	1.34(1.04, 1.71)	0.023	1.3(1.14, 1.48)	<0.001
Model 1 + Wall area % subsegmental				1.2 (1.14, 1.26)	<0.001
Model 1 + Pi10 × 100				1.02 (1.02, 1.03)	<0.001
Model 1 +FEV1 (in L/sec.)		0.46 (0.37, 0.58)	<0.001	0.29 (0.26, 0.32)	<0.001
Model 1 + Wood smoke exposure		1.33 (1.01, 1.75)	0.02
Model 1 + tCc16 (ng/mL)		0.72 (0.57, 0.92)	0.01

Multivariable ordinal logistic regression including preselected baseline characteristics and exposure variables as predictors and rank ordered chronic bronchitis severity groups as dependent variable. Standard covariates included age, sex, predominant minority, obesity, pack-years current smoker, dust and fumes exposure and the comorbidity hypertension. The odds ratio for wall area %, Pi10, FEV₁, wood smoke, and tCC16 were obtained from separate models adjusted for model 1 covariates.

Pi10: standardized airway wall thickness of an airway with an internal diameter of 10mm.

Data for wall area % subsegmental was available in only 1,444 subjects of the COPDGene Cohort.

FEV₁: forced expiratory volume in liters during the first second. tCC16: logarithmically transformed club cell protein 16.