Table 2.

ORs and 95% CIs of known DTC risk factors

Variables	Cases (n = 203)	Controls (n = 212)	Crude OR1 (95% CI)	Adjusted OR2 (95% CI)
Ethnic group
Both parents European	57	38	1*	1*
Both parents African	49	75	0.4 (0.3 – 0.8)	0.4 (0.2 – 0.8)
Other (mixed race)	97	99	0.6 (0.4 – 1.1)	0.7 (0.4 – 1.2)
Education level
Secondary school level and below	23	18	1*	1*
High school	56	66	0.8 (0.4 – 1.6)	1.0 (0.4 – 2.1)
Pre-university	57	57	0.9 (0.4 – 1.9)	1.2 (0.5 – 2.5)
University	67	71	0.9 (0.4 – 1.8)	1.0 (0.4 – 1.2)
Height (m)
Men <1.71; women <1.59	60	71	1*	1*
Men 1.71–≤1.78; women 1.59–≤1.65	74	66	1.3 (0.8 – 2.1)	1.37 (0.8 – 2.3)
Men >1.78; women >1.65	69	75	1.1 (0.7 – 1.7)	1.21 (0.7 – 2.0)
BMI
<25	93	125	1*	1*
25 – 30	74	58	1.8 (1.1 – 2.8)	1.7 (1.1 – 2.8)
>30	36	29	1.8 (1.0 – 3.2)	1.7 (0.9 – 3.2)
Smoking status
Never	144	125	1*	1*
Ever	59	87	0.6 (0.4 – 0.9)	0.6 (0.4 – 0.9)
Number of pregnancies (only for women)
Nullipara	16	32	1*	1*
1	16	32	1.2 (0.5 – 2.8)	1.3 (0.5 – 3.4)
2	34	32	2.6 (1.1 – 5.9)	2.5 (1.1 – 6.1)
3 and more	113	77	3.7 (1.8 – 7.9)	3.8 (1.7 – 8.3)
Exposure to ionizing radiation3
None	188	200	1*	1*
Radiotherapy	6	3	2.2 (0.5 – 9.1)	1.9 (0.4 – 9.8)
Head, neck, or thorax scanner4	4	2	2.3 (0.4 – 12.8)	2.4 (0.4 – 15.2)
Occupational exposure	5	7	0.8 (0.2 – 2.6)	0.7 (0.2 – 2.4)

¹tratified for gender and age classes.

²Stratified for gender and age classes and adjusted for all the following factors: smoking status, ethnic group, level of education, number of pregnancies, height, and BMI, at the exception of the studied factor.

³The numbers are the cases and controls for the ‘yes’ modality of each variable.

⁴Excluding cases or controls treated by radiotherapy (n = 9).

^*Reference category.