Table 4.

Multivariable-Adjusted Associations Between Exposure to Environmental Tobacco Smoke and Risk of Late-Diagnosis Incident Fibroids in the SWAN Study Population

		a) All Women (n=2575)					b) Restricted to Non-Hispanic White (n=1255)				c) Restricted to African-Americans (n=631)
		Cases	OR	95%CI Lower	95%CI Upper		Cases	OR	95%CI Lower	95%CI Upper	Cases	OR	95%CI Lower	95%CI Upper
Model with Main Effects
ETS Exposure >1 vs. 0 person-hours/week		512	1.28	1.03	1.60	*	251	1.30	0.98	1.73	162	1.05	0.73	1.50
Former Smoker vs. Never			0.82	0.51	1.33			0.84	0.43	1.63		0.68	0.33	1.41
Current Smoker vs. Never			0.78	0.55	1.13			0.82	0.50	1.34		0.60	0.35	1.02
Model with ETS x Smoking Status Interactions
ETS Exposure >1 vs. 0 person-hours/week, in Never Smokers		439	1.34	1.06	1.70	¥	220	1.38	0.99	1.93	132	1.15	0.73	1.82
ETS Exposure >1 vs. 0 person-hours/week, in Former Smokers		7	2.57	1.05	7.23	¥	2	2.36	0.70	10.71	3	1.31	0.29	6.87
ETS Exposure >1 vs. 0 person-hours/week, in Current Smokers		66	0.68	0.38	1.24		29	0.97	0.37	2.83	27	0.63	0.26	1.63

^*p-values < 0.05 were considered statistically significant.

^¥p-interactions < 0.20 were considered statistically significant.

Discrete-time proportional odds models were used to obtain the conditional odds ratio (OR) of incident self-reported diagnosis of fibroids. Time-varying passive smoke exposure and covariates were lagged by 1 follow-up year. The multivariable-adjusted models controlled for time-varying bioavailable estradiol, time-varying sex hormone use for any reason, age at baseline, time-varying body mass index, time-varying smoking status (never, past, current), being within 2–5 days of menstrual cycle at blood draw, time-varying physical activity, time-varying alcohol use, highest educational attainment at baseline, age at menarche, pack years of smoking at baseline. The timescale of the models were further stratified by study site - race/ethnicity and menopausal status (post- and late-peri menopause vs. pre- and early peri-menopause), fitting separate baseline intercepts for each strata. (b) Model was restricted to non-Hispanic White women (c) Model was restricted to African-American women. Analyses were not restricted to Hispanic, Chinese, and Japanese women due to small sample sizes. All analyses were restricted to women without self-reported fibroids and cancer at baseline.