Table 3.

Hazard Ratios for Incident Colon and Rectal Cancer in Relation to Body Mass Index Women in the National Institutes of Health-AARP Diet and Health Study Cohort, 1995–1996

	Colon Cancera				Rectal Cancera
	No. of Cases	MVHRb	95% CI	P for Trendc	No. of Cases	MVHRb	95% CI	P for Trendc
BMId at baseline				0.20				0.45
<18.5	14	1.33	0.76, 2.30		6	1.94	0.82, 4.58
18.5–21.9	148	1.00	Referent		43	1.00	Referent
22.0–22.9	68	1.00	0.75, 1.34		22	1.15	0.68, 1.93
23.0–24.9	176	1.08	0.87, 1.35		50	1.07	0.71, 1.63
25.0–27.4	207	1.11	0.89, 1.38		64	1.21	0.82, 1.81
27.5–29.9	127	1.15	0.90, 1.47		32	1.01	0.63, 1.61
30.0–32.4	82	1.00	0.76, 1.32		20	0.85	0.49, 1.47
32.5–34.9	54	1.07	0.78, 1.48		20	1.45	0.84, 2.51
≥35	86	1.23	0.93, 1.64		25	1.28	0.76, 2.16
HRc per 5 kg/m2		1.05	0.98, 1.12			1.05	0.92, 1.19
BMId at 50 years of age				0.002				0.96
<18.5	18	1.52	0.94, 2.46		2	0.45	0.11, 1.84
18.5–21.9	220	1.00	Referent		79	1.00	Referent
22.0–22.9	102	1.06	0.84, 1.34		24	0.70	0.44, 1.10
23.0–24.9	234	1.15	0.96, 1.39		69	0.93	0.67, 1.30
25.0–27.4	194	1.19	0.98, 1.45		58	0.97	0.69, 1.37
27.5–29.9	69	1.08	0.82, 1.42		19	0.70	0.41, 1.21
30.0–32.4	52	1.24	0.91, 1.70		11	0.73	0.39, 1.38
32.5–34.9	25	1.14	0.74, 1.74		11	1.40	0.74, 2.66
≥35	48	1.82	1.31, 2.52		9	0.93	0.46, 1.89
HRc per 5 kg/m2		1.13	1.05, 1.23			1.00	0.85, 1.16
BMId at 35 years of age				0.01				0.69
<18.5	29	0.91	0.62, 1.35		14	1.40	0.81, 2.43
18.5–21.9	416	1.00	Referent		137	1.00	Referent
22.0–22.9	143	1.17	0.97, 1.42		34	0.86	0.59, 1.25
23.0–24.9	190	1.06	0.89, 1.26		49	0.81	0.58, 1.13
25.0–27.4	106	1.15	0.92, 1.43		27	0.87	0.57, 1.34
27.5–29.9	36	1.38	0.98, 1.94		9	1.05	0.53, 2.06
30.0–32.4	23	1.41	0.92, 2.15		3	0.37	0.09, 1.51
≥32.5	19	1.48	0.92, 2.38		9	2.24	1.13, 4.43
HRc per 5 kg/m2		1.16	1.04, 1.30			1.05	0.84, 1.30
BMId at 18 years of age				0.14				0.46
<18.5	150	0.97	0.81, 1.16		49	1.09	0.79, 1.50
18.5–21.9	553	1.00	Referent		168	1.00	Referent
22.0–22.9	87	1.06	0.85, 1.33		24	0.94	0.61, 1.46
23.0–24.9	89	0.89	0.71, 1.12		22	0.74	0.47, 1.16
25.0–27.4	50	1.17	0.88, 1.57		13	0.96	0.54, 1.73
27.5–29.9	17	1.44	0.89, 2.34		3	0.86	0.27, 2.69
≥30.0	16	1.39	0.89, 2.33		3	0.92	0.29, 2.88
HRc per 5 kg/m2		1.11	0.96, 1.29			0.89	0.66, 1.21

Abbreviations: BMI, body mass index; CI, confidence interval; HR, hazard ratio; MVHR, multivariable hazard ratio.

^a There were 4 women with synchronous colon and rectal cancers.

^b Calculated using PROC PHREG in SAS, version 9.1. We took relative risk (used in the text) to be equivalent to HR. All analyses were adjusted for age (in the baseline hazard of the Cox regression) and the following covariates: race/ethnicity, educational level, physical activity level, smoking status, alcohol consumption, and use of menopausal hormone therapy.

^c Calculated after excluding subjects whose BMI at a given age was less than 18.5.

^d Weight (kg)/height (m)².