Table 3.

Mortality associated with sex in pediatric patients diagnosed with leukemia, 1973–2006.

Covariates	AHR	99% CI	P
Sex
Boys	1.0	Ref	Ref
Girls	0.88	0.81–0.95	<0.0001
Race
White	1.0	Ref	Ref
Black	1.47	1.31–1.66	<0.0001
Age at diagnosis (years)
<1.0	1.0	Ref	Ref
1.0−4.0	0.24	0.21–0.28	<0.0001
5.0–9.0	0.31	0.26–0.37	<0.0001
10.0–14.0	0.54	0.46–0.62	<0.0001
15.0−19.0	0.83	0.71–0.96	0.001
Year of diagnosis
1973–1977	1.0	Ref	Ref
1978–1982	0.70	0.61–0.81	<0.0001
1983–1987	0.57	0.49–0.65	<0.0001
1988–1992	0.40	0.35–0.47	<0.0001
1993–1997	0.36	0.32–0.42	<0.0001
1998–2002	0.30	0.26–0.34	<0.0001
2003–2006	0.27	0.23–0.31	<0.0001
Number of primaries
1.0	1.0	Ref	Ref
≥ 2.0	1.32	1.10–1.33	0.002
Radiation
Yes	1.0	Ref	Ref
No	1.21	1.10–1.33	<0.0001

Notes and abbreviations: the significance level was 0.01. CI = confidence interval. AHR = adjusted hazard ratio, ref = the reference group or class.