Table 1.
Demographics and Clinical Characteristics of the Study Participants
| Characteristic | Entire Cohort |
Non-Hispanic Whites |
Hispanics |
P | |||
|---|---|---|---|---|---|---|---|
| No. | % | No. | % | No. | % | ||
| Cohort size | 327 | 100 | 158 | 48.3 | 169 | 51.7 | — |
| Age, years | .91 | ||||||
| Median | 4.0 | 4.5 | 4.0 | ||||
| Range | 1-19 | 1-19 | 1-18 | ||||
| Age at study participation, years | .85 | ||||||
| Median | 6.0 | 6.0 | 6.0 | ||||
| Range | 2-20 | 2-20 | 2-20 | ||||
| Male sex | 218 | 66.7 | 104 | 65.8 | 114 | 67.5 | .75 |
| WBC count at diagnosis≥ 50,000/μL | 61* | 18.8* | 31 | 19.6 | 30* | 18.0* | .70 |
| High-risk disease (NCI criteria) | 124* | 38.2* | 63 | 39.9 | 61* | 36.5* | .53 |
| Cytogenetics | |||||||
| Unfavorable† | 15* | 4.9* | 9* | 6.0* | 6* | 3.8* | .37 |
| Favorable† | 135* | 43.8* | 64* | 42.7* | 71* | 44.9* | .69 |
| Daily MP dose-intensity‡ | .18 | ||||||
| Mean | 82.3 | 80.6 | 83.8 | ||||
| SD | 21.3 | 21.4 | 21.2 | ||||
| TPMT activity | .16 | ||||||
| Median | 17.4* | 17.9* | 17.1* | ||||
| Range | 0.5-31.4* | 0.5-31.4* | 7.7-26.9* | ||||
| Person-days of adherence monitoring | 53,394 | 26,123 | 27,271 | — | |||
| Annual household income < $20,000 | 83* | 26.5* | 10* | 6.5* | 73* | 45.6* | < .001 |
| Paternal education ≤ high school | 159* | 50.2* | 42 | 26.6 | 117* | 73.6* | < .001 |
| Maternal education ≤ high school | 140* | 43.6* | 32 | 20.3 | 108* | 66.3* | < .001 |
| Parental education ≤ high school | 127* | 39.4* | 24 | 15.2 | 103* | 62.8* | < .001 |
| Single mother | 36* | 11.2* | 10 | 6.3 | 26* | 15.8* | .007 |
| Monolingual, Spanish speaking | 79* | 24.2* | NA | NA | 79* | 47.0* | — |
| Time from start of maintenance to study entry, years | .65 | ||||||
| Median | 0.8 | 0.8 | 0.9 | ||||
| Range | 0.2-2.2 | 0.2-2.1 | 0.2-2.2 | ||||
| Time from diagnosis to study entry, years | .56 | ||||||
| Median | 1.6 | 1.6 | 1.6 | ||||
| Range | 0.9-3.0 | 0.9-2.9 | 0.9-3.0 | ||||
| Length of follow-up from diagnosis, years | < .001 | ||||||
| Median | 5.3 | 5.9 | 4.6 | ||||
| Range | 1.3-10.3 | 1.5-10.3 | 2.0-10.1 | ||||
| Length of follow-up from study entry, years | < .001 | ||||||
| Median | 3.7 | 4.3 | 2.9 | ||||
| Range | 0.4-8.8 | 0.4-8.1 | 0.4-8.8 | ||||
| Length of follow-up from study exit, years | < .001 | ||||||
| Median | 3.3 | 3.8 | 2.4 | ||||
| Range | 0-8.5 | 0-8.0 | 0-8.5 | ||||
| Relapse | 27 | 8.3 | 8 | 5.1 | 19 | 11.2 | .04 |
Abbreviations: MP, mercaptopurine; NA, not applicable; NCI, National Cancer Institute; SD, standard deviation; TPMT, thiopurine methyltransferase.
*
Statistics were calculated for this table by excluding patients with missing values for the characteristics.
†
Unfavorable chromosomal abnormalities included t(9;22), t(4;11), hypodiploidy, or extreme hypodiploidy; favorable cytogenetics included one or more of the following: t(12;21), hyperdiploidy, trisomy 4 and 10, or trisomy 4, 10, and 17.
‡
MP dose-intensity: mean MP dose (mg/m2 body surface area) prescribed over the No. of days that the drug was prescribed divided by the planned daily protocol dosage (75 mg/m2).