Characteristics of patients at study entry
| Characteristic . | Normal MRI . | Silent infarct . | P . |
|---|---|---|---|
| n (%) | 58 (73.4) | 21 (26.6) | |
| Age, y | 12.1 ± 0.43 | 12.6 ± 0.67 | NS |
| Male, n (%) | 25 (43.1%) | 8 (38.1%) | NS* |
| Hemoglobin, g/dL | 9.2 ± 0.35 | 9.7 ± 0.29 | NS |
| White cell count, ×10−3/mm3† | 11.4 ± 0.62 | 11.1 ± 0.81 | NS |
| Reticulocyte count, %† | 7.3 ± 0.59 | 8.2 ± 1.29 | NS |
| Platelet count, ×10−3/mm3‡ | 357 ± 18.0 | 387 ± 23.3 | NS |
| Hemoglobin S, %§ | 19.9 ± 1.3 | 20.2 ± 2.1 | NS |
| Indirect bilirubin, mg/dL‖ | 2.58 ± 0.24 | 2.55 ± 0.25 | NS |
| LDH, IU/l§ | 477 ± 34.8 | 419 ± 34.0 | NS |
| Four α-globin genes | 41 (70.7%) | 19 (90.5%) | NS* |
| TCD, cm/sec¶ | 212 ± 1.3 | 220 ± 4.4 | NS |
| Characteristic . | Normal MRI . | Silent infarct . | P . |
|---|---|---|---|
| n (%) | 58 (73.4) | 21 (26.6) | |
| Age, y | 12.1 ± 0.43 | 12.6 ± 0.67 | NS |
| Male, n (%) | 25 (43.1%) | 8 (38.1%) | NS* |
| Hemoglobin, g/dL | 9.2 ± 0.35 | 9.7 ± 0.29 | NS |
| White cell count, ×10−3/mm3† | 11.4 ± 0.62 | 11.1 ± 0.81 | NS |
| Reticulocyte count, %† | 7.3 ± 0.59 | 8.2 ± 1.29 | NS |
| Platelet count, ×10−3/mm3‡ | 357 ± 18.0 | 387 ± 23.3 | NS |
| Hemoglobin S, %§ | 19.9 ± 1.3 | 20.2 ± 2.1 | NS |
| Indirect bilirubin, mg/dL‖ | 2.58 ± 0.24 | 2.55 ± 0.25 | NS |
| LDH, IU/l§ | 477 ± 34.8 | 419 ± 34.0 | NS |
| Four α-globin genes | 41 (70.7%) | 19 (90.5%) | NS* |
| TCD, cm/sec¶ | 212 ± 1.3 | 220 ± 4.4 | NS |
Plus-minus values are means ± SE. P-values were calculated by Student t-test, except where indicated otherwise.
MRI indicates magnetic resonance imaging; LDH, lactate dehydrogenase; TCD, transcranial Doppler ultrasonography; and NS, not significant (P ≥ .05).
The value was calculated by Fisher exact test.
Two patients in the transfusion-halted group were excluded, one because no laboratory values were available at study entry and the other because the blood sample was too old to be processed.
Four patients were excluded, 1 from the continued-transfusion group because the blood sample was clotted and could not be processed, and 3 from the transfusion-halted group (1 because no blood sample was available at study entry, 1 because the blood sample was too old to be processed, and 1 because the blood sample was clotted).
Laboratory values at study entry were not available for 1 patient in the transfusion-halted group. LDH normal reference range is 120-246 IU/l.
Two patients were excluded, one in the transfusion-halted group because laboratory values at study entry were not available and the other in the continued-transfusion group because of missing data. To convert values for bilirubin to micromoles per liter, multiply by 17.1.
The value is the average of 2 qualifying TCD examinations performed before transfusion that showed abnormal velocities or 1 TCD examination if the velocity was < 220 cm/second (for new patients entering the STOP II trial).