A cross-sectional study of secondhand smoke exposure and respiratory symptoms in non-current smokers in the U.S. trucking industry: SHS exposure and respiratory symptoms

Table 3 Effect modifications on the association between SHS exposure and respiratory symptoms among 1,562 non-current smoking workers ^a

Exposure metric	Stratification factors	Chronic cough			Chronic phlegm			Any wheeze
Exposure metric	Stratification factors	n	OR	95% CI	n	OR	95% CI	n	OR	95% CI
Current Exposure	Former smoking
	No	870	1.62	0.97 - 2.69	870	1.48	0.92 - 2.38	840	1.78	1.32 - 2.39
	Yes	692	1.31	0.73 - 2.33	692	1.69	0.98 - 2.93	662	1.73	1.21 - 2.45
	Obesity (BMI ≥30 kg/m²)
	No	1033	1.68	1.04 - 2.73	1033	1.27	0.81 - 1.98	995	1.72	1.31 - 2.26
	Yes	522	1.19	0.64 - 2.22	522	2.06	1.11 - 3.83	500	1.99	1.33 - 2.99
	Currently in urban area
	No	528	2.39	1.14 - 4.99	528	2.97	1.46 - 6.01	506	2.07	1.40 - 3.05
	Yes	1034	1.24	0.78 - 1.95	1034	1.19	0.78 - 1.83	996	1.67	1.26 - 2.22
	Childhood SHS exposure
	No	459	2.31	1.06 - 5.02	459	2.42	1.06 - 5.53	437	1.41	0.94 - 2.13
	Yes	1077	1.24	0.80 - 1.93	1077	1.38	0.92 - 2.06	1040	1.97	1.50 - 2.60
Childhood Exposure	Former smoking
	No	870	1.18	0.71 - 1.95	870	1.95	1.15 - 3.31	840	1.06	0.78 - 1.45
	Yes	692	1.16	0.60 - 2.23	692	1.57	0.85 - 2.92	662	1.24	0.84 - 1.83
	Obesity (BMI ≥30 kg/m²)
	No	1033	0.86	0.54 - 1.39	1033	1.57	0.96 - 2.59	995	0.92	0.69 - 1.23
	Yes	522	2.63	1.21 - 5.75	522	2.63	1.31 - 5.29	500	1.93	1.25 - 2.95
	Currently in urban area
	No	528	0.86	0.43 - 1.71	528	1.15	0.60 - 2.19	506	1.08	0.71 - 1.62
	Yes	1034	1.50	0.90 - 2.51	1034	2.47	1.43 - 4.25	996	1.24	0.92 - 1.68
	Current SHS exposure
	No	572	1.80	0.83 - 3.93	572	2.71	1.18 - 6.20	550	0.89	0.60 - 1.33
	Yes	990	1.04	0.65 - 1.66	990	1.63	1.02 - 2.60	952	1.29	0.95 - 1.75

^a Logistic regression model adjusted for age, sex, race, job title, former smoking, pack-years, years since quitting, BMI, region of country, and urban residence except the stratification factor for each model, and also adjusted for either current exposure to SHS or childhood SHS exposure among never smokers or former smokers who quit at least 10 before completing the questionnaire.
* p for interaction < 0.05.

ISSN: 1471-2458