Table 3.

Odds ratios and 95% CI for differentiated thyroid carcinoma associated with thirds and a doubling of IGF-I concentration, overall, by sub-groups, and by tumour characteristics.

		Bottom third		Middle third			Top third				Doublinga
	IGF-I range (median)	< 15.3 (13.0) nmol/lb		15.3 - 19.6 (17.4) nmol/lb			> 19.6 (22.8) nmol/lb
		OR	95% CI	OR	95% CI		OR	95% CI		OR	95% CI		Ptrend	pheterogeneityc
	ncase/ncontrol	105/245		101/245			139/245
Risk overalld
Age-adjusted model	345/735	1	Ref	0.99	0.71	1.39	1.37	0.99	1.91	1.48	1.06	2.08	0.02	–
Multivariable-adjusted modele	345/735	1	Ref	1.00	0.71	1.41	1.37	0.98	1.92	1.46	1.04	2.07	0.03	–
Further adjusted modelf	345/735	1	Ref	1.02	0.72	1.46	1.33	0.93	1.88	1.41	0. 99	2.01	0.06	–
Risk in sub-groupsd
Sex
Male	56/164	1	Ref	1.01	0.45	2.28	1.63	0.73	3.65	1.39	0.61	3.16	0.43
Female	289/571	1	Ref	0.99	0.68	1.44	1.33	0.92	1.91	1.50	1.04	2.18	0.03	0.87
Age at blood collection (years)
< 50	146/310	1	Ref	1.55	0.84	2.84	1.59	0.91	2.78	1.54	0.90	2.66	0.12
≥ 50	199/425	1	Ref	0.79	0.52	1.20	1.39	0.91	2.13	1.45	0.94	2.22	0.09	0.86
Educationg
Less than secondary school	135/273	1	Ref	1.10	0.66	1.86	1.47	0.87	2.48	1.80	1.08	3.00	0.02
Secondary school or more	201/436	1	Ref	0.84	0.53	1.31	1.20	0.79	1.83	1.27	0.83	1.93	0.27	0.27
Smoking
Never	179/390	1	Ref	1.02	0.65	1.60	1.37	0.87	2.17	1.62	1.03	2.56	0.04
Ever	161/326	1	Ref	0.96	0.58	1.58	1.39	0.87	2.24	1.39	0.88	2.20	0.16	0.62
BMI (kg/m2)
< 25	158/347	1	Ref	0.92	0.55	1.53	1.32	0.81	2.16	1.45	0.88	2.38	0.14
≥ 25	187/388	1	Ref	1.05	0.67	1.64	1.44	0.92	2.26	1.55	1.00	2.42	0.05	0.84
Thyroid stimulation hormone (mIU/l)g
< 1.27	204/365	1	Ref	1.03	0.66	1.61	1.37	0.89	2.11	1.46	0.96	2.22	0.08
≥ 1.27	140/366	1	Ref	1.00	0.59	1.67	1.35	0.83	2.22	1.52	0.91	2.52	0.11	0.90
Risk by tumour characteristicsd
Histological typeg
Papillary	253/538	1	Ref	1.30	0.86	1.95	1.62	1.09	2.40	1.69	1.13	2.55	0.01
Follicular	56/122	1	Ref	0.60	0.27	1.38	0.92	0.41	2.08	1.13	0.53	2.37	0.76	0.35
TNM stageg
Localized	101/211	1	Ref	0.92	0.47	1.78	1.48	0.82	2.70	1.44	0.81	2.54	0.22
More advanced	79/172	1	Ref	2.01	1.00	4.06	1.53	0.75	3.13	1.91	0.90	4.08	0.09	0.55
Years between blood collection and diagnosis
< 5	137/293	1	Ref	0.79	0.46	1.35	1.33	0.80	2.21	1.48	0.84	2.61	0.18
≥ 5	208/442	1	Ref	1.15	0.74	1.80	1.42	0.92	2.20	1.48	0.97	2.26	0.07	0.99

^aOR, 95% CI, and p_trend were based on the logarithm (base2) of IGF-I concentrations (as a continuous variable) and correspond to the risk associated with a doubling in IGF-I concentration.

^bTertile cut-points were based on the distribution controls only.

^cP values refer to likelihood ratio χ² test between models of the linear trend in logarithm (base 2) of IGF-I concentrations with and without an interaction term with the variable of interest.

^dAll analyses were logistic regression models conditioned on the matching variables and adjusted for age at blood collection (as a continuous variable).

^eThe multivariable-adjusted model was adjusted for age at blood collection (as a continuous variable), height (as a continuous variable), and BMI (in fifths based on the distribution in controls).

^fThe further adjusted model was in addition to age at blood collection, height, and BMI adjusted for waist to hip ratio (below and above the median based on the distribution in controls; unknown), alcohol (0; > 0 – 9; 10 – 19; ≥ 20 g/d), smoking (never; former; current; unknown), physical activity (inactive; moderately inactive; moderately active or active; unknown), education (less than secondary school; secondary school; university degree; unknown), and in women only, age at first period (< 12; 12 – 14; < 14 years; unknown), number of full term pregnancies and age at first pregnancy (nulliparous; 1 – 2 children and < 25 years; 1 – 2 children and ≥ 25 years; ≥ 3 children and < 25 years; ≥ 3 children and ≥ 25 years; unknown), and for postmenopausal women only, age at menopause (<50; ≥ 50 years; unknown).

^gUnknown for some participants.