Table II.
Differences in Hematological Tests Across the Three “MPH Sensitivity” Groups.
| Characteristic | High MPH Sensitivity n=8 | Medium MPH Sensitivity n=9 | Low MPH Sensitivity n=12 | Statistic | p value |
|---|---|---|---|---|---|
| Age Test Obtained | 3.0 ± 2.2 | 2.8 ± 1.8 | 2.7 ± 1.6 | F=0.07 | >.9 |
| Test to MPH Start Time Interval, yrs | 2.3 ± 1.2 | 2.9 ± 1.7 | 3.5 ± 1.6 | F=1.44 | >.2 |
| Hemoglobin, g/dl | 12.0 ± 1.1 | 12.0 ± 1.2 | 11.7 ± 1.0 | F=0.33 | >.7 |
| Low Hemoglobin, n (%)* | 2 (25) | 1 (11) | 2 (18) | Fisher’s | >.8 |
| Hematocrit, (%) | 34.3 ± 4.2 | 35.3 ± 1.6 | 33.8 ± 2.0 | F=0.59 | >.5 |
| Low Hematocrit, n (%)* | 2 (28) | 0 (0) | 3 (33) | Fisher’s | >.3 |
| MCV, fL | 79.2 ± 2.7 | 78.7 ± 1.0 | 71.9 ± 7.2 | F=5.3 | <.02 |
| Microcytosis, n (%)* | 3 (43) | 1 (17) | 6 (75) | Fisher’s | >.1 |
| RDW, (%) | 14.3 ± 1.5 | 13.0 ± 2.0 | 14.6 ± 1.9 | F=0.90 | >.4 |
| Large RDW, n (%)* | 1 (25) | 1 (17) | 3 (75) | Fisher’s | >.4 |
High, medium, and low MPH sensitivity was based on the relative percent time spent, during the first year of treatment, receiving a high, medium, or low weight-adjusted dose of methylphenidate (MPH) (see Methods section for details).
*
Cutoffs were based on Ref. (Marks et al., 1998), Tables 6 and 8. They varied by age and sex.