. Author manuscript; available in PMC: 2008 May 12.

Published in final edited form as: Am J Epidemiol. 2007 Dec 5;167(5):570–578. doi: 10.1093/aje/kwm343

TABLE 4.

Mean FEV₁ (ml) across quintiles of energy adjusted intake of total fiber, stratified by sex, ethnicity, and smoking status (1987-1989) ^*

	No. of subjects	Quintiles of energy-adjusted intake of total fiber					Difference in FEV₁ (ml) between quintiles 5 and 1 (95% CI)	p value for trend^†	p value for interaction^‡
	No. of subjects	1 (lowest)	2	3	4	5	Difference in FEV₁ (ml) between quintiles 5 and 1 (95% CI)	p value for trend^†	p value for interaction^‡
Sex
Female	6,799	2,325	2,337	2,354	2,376	2,369	44.0 (7.2,80.9)	0.006	0.394
Male	5,098	3,208	3,234	3,238	3,279	3,287	79.8 (22.5,137.0)	0.003	0.394
Ethnicity
Black	2,798	2,506	2,524	2,550	2,557	2,575	68.4 (5.3,131.5)	0.021	0.612
White	9,099	2,860	2,877	2,880	2,921	2,921	60.7 (22.7,98.7)	<0.001	0.612
Smoking status
Never	5,174	2,771	2,779	2,785	2,821	2,822	50.7 (6.8,94.5)	0.005	0.903
Current/past	6,723	2,695	2,719	2,734	2,759	2,759	64.2 (17.2,111.1)	0.003	0.903

Covariates included age, sex, height, square of height, study center, ethnicity, smoking status (current smoker, former smoker with ETS, former smoker without ETS, never smoker with ETS, never smoker without ETS), pack years, BMI, occupation, education, diabetes status, traffic density, total energy intake, glycemic index, micronutrients (carotenoids, vitamins C, D, E, and omega-3 fatty acids) from both food and supplements, and cured meat.

^†

Tests for linear trends across increasing quintiles of fiber intake used the median values in each quintile.

^‡

Likelihood ratio test for interaction (effect modification) by sex, ethnicity, and smoking status.