Age Variance in the Survival of United States Pediatric Leukemia Patients (1973–2006)
Table 3
(a) Mortality associated with age at diagnosis in pediatric patients with leukemia, 1973–2006, in an adjusted multivariable Cox proportional hazard model stratified by the year of diagnosis
Covariates
Adjusted hazard ratio (AHR)
99% CI of HR
Age at diagnosis (yrs)
<1.0
1.0
ref
ref
1.0–4.0
0.24
0.21–0.28
<0.0001
5.0-9.0
0.31
0.26–0.36
<0.0001
10.0–14.0
0.54
0.46–0.62
<0.0001
15.0–19.0
0.82
0.70–0.95
0.001
Sex
Boys
1.0
ref
ref
Girls
0.87
0.81–0.94
<0.0001
Race
White
1.0
ref
ref
Black
1.47
1.29–1.65
<0.0001
No. of primaries
1.0
1.0
ref
ref
≥ 2.0
1.30
1.03–1.63
0.004
Radiation
Yes
1.0
ref
ref
No
1.22
1.11–1.34
<0.0001
Notes and Abbreviations. The significance level was 0.01. CI: Confidence interval.
(b) Mortality associated with age at diagnosis in pediatric patients with Leukemia, 1973–2006, in an adjusted multivariable Cox proportional hazard model stratified by the year of diagnosis in a subset of data with cell type only information
Covariates
AHR
99% CI of HR
Age at diagnosis (yrs)
<1.0
1.0
ref
ref
1.0–4.0
0.14
0.10–0.20
<0.0001
5.0–9.0
0.21
0.15–0.30
<0.0001
10.0–14.0
0.38
0.27–0.54
<0.0001
15.0–19.0
0.65
0.46–0.91
0.001
Sex
Boys
1.0
ref
ref
Girls
0.86
0.72–1.01
0.018
Race
White
1.0
ref
ref
Black
1.45
1.10–1.93
0.001
No. of primaries
1.0
1.0
ref
ref
≥2.0
1.79
0.93–3.45
0.022
Radiation
Yes
1.0
ref
ref
No
1.01
0.82–1.24
0.945
Cell type
T-cell
1.0
ref
ref
B-cell, B-precursor
0.72
0.59–0.88
<0.0001
Notes and abbreviations. The significance level was 0.01. CI: confidence interval. Cell type information is available since 1980 and for only total of 5988 patients (917 T-cell and 5071 B-cell/B-precursor). The proportion of B-cell/B-precursor increases precipitously over the year of diagnosis starting with 0.0% in 1980 to 89% in 2006. The above table illustrates an adjusted analysis with cell types restricting the sample size to 5988 patients. AHR: adjusted hazard ratio; ref: referent group.
