TABLE 4.

ADDITIVE EFFECT OF NON-HISPANIC ETHNICITY AND EXPOSURE TO WOOD SMOKE ON CHRONIC OBSTRUCTIVE PULMONARY DISEASE OUTCOMES (N = 1,861)*

Exposure Variable	FEV1 % Predicted†‡		Airflow Obstruction (GOLD)		Chronic Bronchitis
	PE (SE)	P Value	OR (95% CI)	P Value	OR (95% CI)	P Value
Hispanics with wood smoke, n = 115 (6.2%)	0.02 (0.01)	0.21	1.97 (1.00–3.86)	0.05	1.22 (0.73–2.04)	0.44
Non-Hispanics without wood smoke, n = 1,144 (61.5%)	−0.02 (0.01)	0.004	2.20 (1.37–3.52)	0.001	1.21 (0.85–1.73)	0.28
Non-Hispanics with wood smoke, n = 400 (21.5%)	−0.07 (0.01)	< 0.001	4.30 (2.59–7.12)	< 0.001	2.14 (1.45–3.16)	< 0.001

Definition of abbreviations: CI = confidence interval; OR = odds ratio; PE = point estimate.

^*The referent group included Hispanics without current exposure to wood smoke (n = 202 or 10.9%). All models were adjusted for sex, age categories, current smoking, obesity (body mass index ≥ 30 kg/m²), educational status (at least high school or not), and heavy smoking history (pack-yr > 40 or not). Results for absolute postbronchodilator FEV₁/FVC ratio and for airflow obstruction defined by NHANES III criterion were similar to those for FEV₁ % predicted and airflow obstruction defined by GOLD criterion, respectively.

^†Nonparametric tests using GLM regression models with a Poisson distribution and log link were used to evaluate the continuous FEV₁ % predicted outcome and logistic regression models were used for airflow obstruction and chronic bronchitis.

^‡Among the various chronic obstructive pulmonary disease outcome measures, the only statistically significant multiplicative interaction using two-way regression analyses between non-Hispanic ethnicity and wood smoke exposure was on FEV₁ % predicted (P < 0.001). For the remaining outcome measures, the effect sizes in row 3 were approximately the sum of the individual effect sizes for rows 1 and 2, indicating an additive effect.