Table 2.

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

Covariates	Hazard ratio (HR)	99% CI	P
Sex
Male	1.00	Ref	Ref
Female	0.86	0.80–0.93	<0.0001
Race
White	1.00	Ref	Ref
Black	1.54	1.36–1.74	<0.0001
Age at diagnosis (yrs)
<1.0	1.00	Ref	Ref
1.0−4.0	0.26	0.22–0.30	<0.0001
5.0–9.0	0.33	0.28–0.39	<0.0001
10.0–14.0	0.56	0.48–0.66	<0.0001
15.0 −19.0	0.89	0.77–1.04	0.05
Number of primaries
1.0	1.00	Ref	Ref
≥ 2.0	1.75	1.40–2.20	<0.0001
Beam radiation
Yes	1.00	Ref	Ref
No	0.84	0.77–0.92	<0.0001

Notes and abbreviations: the significance level was 0.001. CI = confidence interval, ref = reference group or class.