Table 1. Characteristics of Acute Non-Lymphocytic Leukemia Cases and Controls in the SETIL Case-Control Study, Italy, 1998-2003.

	AnLL cases		Controls matched to AnLL cases		All sampled controls		P valuea
	No.	%	No.	%	No.	%
Genderd
Female	39	47.6	62	48.4	482	46.2
Male	43	52.4	66	51.6	562	52.8	Na
Age at study reference date (years)d
≤1	21	25.6	35	27.3	156	14.9
2–3	13	15.9	18	14.1	351	33.6
4–5	13	15.9	15	11.7	233	22.3
≥6	35	42.7	60	46.9	304	29.1	Na
Residence area (part of Italy)d
North (except Lombardy)	22	26.8	33	25.8	250	24.0
Lombardy	16	19.5	32	25.0	260	24.9
Center	17	20.7	23	18.0	257	24.6
South and islands	27	32.9	40	31.2	277	26.5	Na
Birth order
First born	39	47.6	68	53.1	551	52.8
Second born	31	37.8	39	30.5	379	36.3
Third born and others	12	14.6	21	16.4	113	10.8	0.49b
Birth weight (g)
<3,000	19	23.2	31	24.2	239	22.9
3,000–3,299	18	22.0	28	21.9	246	23.6
3,300–3,599	23	28.0	29	22.7	254	24.4
≥3,600	22	26.8	40	31.2	304	29.2	0.89b
Duration of breastfeeding (months)
0	12	14.6	26	20.5	232	22.3
1–3	32	39.0	32	25.2	267	25.7
4–6	19	23.2	37	29.1	233	22.4
>6	19	23.2	32	25.2	308	29.6	0.04b
Maternal age at child's birth (years)
≤24	14	17.1	23	18.1	140	13.4
25–29	25	30.5	41	32.3	382	36.7
30–34	30	36.6	44	34.6	359	34.5
≥35	13	15.8	19	15.0	160	15.4	0.65b
Birth year of the mother
<1960	15	18.3	22	17.3	145	13.9
1960–1964	27	32.9	32	25.2	328	31.5
1965–1969	22	26.8	53	31.7	373	35.8
≥1970	18	22.0	20	15.8	195	18.7	0.36b
Maternal educational level
Less than high school	46	56.1	45	35.2	400	38.4
High school	26	31.7	64	50.0	503	48.3
University	10	12.2	19	14.8	139	13.3	<0.01b
Paternal age at child's birth (years)
≤24	3	3.7	6	4.7	33	3.3
25–29	18	22.2	29	22.8	241	23.8
30–34	3	40.7	45	35.4	385	38.0
≥35	27	33.3	47	37.0	353	34.9	0.96b
Paternal educational level
Less than high school	47	58.0	54	42.2	463	44.6
High school	24	29.6	59	46.1	424	40.9
University	10	12.4	15	11.7	151	14.6	0.06b
Parental occupational exposure to benzene
Absent	80	97.6	126	98.4	1,009	96.7
Present	2	2.4	2	1.6	35	3.3	0.65c

Abbreviations: AnLL, acute non-lymphocytic leukemia; NA, not appropriate.

^aComparison between cases and all controls sampled in the SETIL study (AnLL controls + ALL controls).

^b P values from χ2 test.

^c P values from Fisher exact test.

^dMatching variables.