Table 1

Characteristics of study participants by cases and controls and lifetime night shift work status, including univariate ORs

Characteristic	Cases					Controls					Univariate
	No night shift work (N=89)		Night shift work (N=43)		p Value^*	No night shift work (N=361)		Night shift work (N=144)		p Value^*	OR	p Value^†
	No.	%	No.	%	p Value^*	No.	%	No.	%	p Value^*	OR	p Value^†
Education (years)
7	15	17	7	16	0.96	63	18	35	24	0.24	1	0.01
8–9	16	18	9	21		73	20	21	15		1.2
10	29	33	13	30		124	35	49	34		1.4
>10	26	29	14	33		97	27	38	26		2.0
Body mass index (kg/m²)
<25	51	58	20	49	0.38	197	55	77	53	0.89	1	0.85
≥25	37	42	21	51	0.38	144	40	58	40	0.89	1.0	0.85
Age at menarche (years)
<11	15	17	3	7	0.14	34	10	15	10	0.63	1	0.02
11–14	44	49	38	88		298	82	114	79		0.6
≥14	9	10	2	5		29	8	15	10		0.6
Age at menopause (years)
<45	4	4	3	7	0.51	30	8	16	6	0.62	1	0.16
45–50	21	21	8	19		73	20	28	19		1.7
50–55	22	22	6	14		54	15	21	15		2.3
≥55	2	2	2	5		12	3	2	2		2.0
Childbirths
None	13	15	9	21	0.58	36	10	16	11	0.90	1	0.15
1–2 children	53	60	22	51		227	63	91	63		0.6
≥3 children	23	26	12	28		93	26	37	26		0.6
Oral contraceptive use (years)
Never	35	39	16	37	0.74	133	37	44	31	0.13	1	0.82
1–10	30	34	18	42		132	37	67	47		0.9
≥10	21	24	9	21		77	21	27	19		1.1
Hormone replacement therapy use (years)
Never	71	79	32	74	0.46	324	86	124	86	0.47	1	0.003
1–5 years	8	9	7	16		24	8	12	8		1.5
≥6 years	10	11	4	9		13	4	8	6		2.3
Satisfactory job influence
No	15	17	10	23	0.44	59	16	24	17	0.99	1	0.52
Yes	70	79	32	74	0.44	292	81	118	82	0.99	0.9	0.52
High workload and work pace
No	55	62	15	35	0.02	203	42	61	42	0.03	1	0.35
Yes	30	34	25	58	0.02	150	59	82	57	0.03	1.2	0.35
Physical activity at work
Light	59	66	28	65	0.51	257	71	87	60	0.03	1	0.38
Heavy	19	19	12	28	0.51	96	27	52	36	0.03	0.8	0.38
Alcohol consumption (≥1 unit/week; 1 unit=12 g alcohol)
Never	7	8	4	9	0.78	42	12	12	8	0.78	1	0.35
Ever	82	92	39	91	0.78	319	88	132	91	0.78	1.2	0.35
Tobacco smoking
Never	24	27	12	28	0.83	132	37	46	32	0.64	1	0.15
Former	29	33	12	28		97	27	42	29		1.3
Current	36	36	19	44		129	36	54	38		1.4
1–10 years	26	7	12	8	0.56	26	7	12	8	0.89	1.5	0.25
>10 years	190	53	82	57	0.56	190	53	82	57	0.89	1.4	0.25
Occupational exposure to radar or electromagnetic fields (EMF)
Never	818	99	31	7	<0.001	351	97	133	92	<0.01	1	0.39
Ever	1	1	11	26	<0.001	10	3	11	8	<0.01	1.2	0.39
Occasional sunbathing frequency
Never/rare	60	67	27	63	0.54	207	57	61	42	0.003	1	0.01
Always/at least once weekly	28	31	16	37	0.54	152	42	81	56	0.003	0.6	0.01
Diurnal preference
Morning	38	43	18	42	0.31	222	62	66	46	0.002	1	0.02
Evening	25	28	17	39		66	18	45	31		1.9
Neither	24	27	8	19		72	20	32	22		1.6

Numbers may not add up owing to missing values.
↵* Pearson χ²test.
↵† Wald χ²test.