Clinical and laboratory characteristics of sickle cell disease patients according to hydroxyurea treatment
| . | Not on hydroxyurea . | Hydroxyurea treatment . | P* . | ||
|---|---|---|---|---|---|
| n . | Result . | n . | Result . | ||
| Age, y | 247 | 11 (10-12) | 150 | 13 (12-14) | <.001 |
| Female sex, no. (%) | 247 | 123 (50) | 150 | 67 (45) | .3 |
| Severe sickling phenotype, hemoglobin SS, Sβ0 thalassemia, or SDLA, no. (%) | 244 | 171 (70) | 149 | 127 (85) | .001 |
| Oxygen saturation, %† | 233 | 97 (97-98) | 144 | 98 (98-99) | .001 |
| Change in oxygen saturation during 6-minute walk, %† | 183 | 0 (−1-0) | 132 | 0 (−1-0) | .6 |
| Tricuspid regurgitation velocity, m/s† | 227 | 2.3 (2.2-2.3) | 143 | 2.3 (2.2-2.3) | .5 |
| Tricuspid regurgitation velocity, 2.5 m/s or higher, no. (%) | 227 | 47 (21) | 143 | 33 (23) | .6 |
| Tricuspid regurgitation velocity, 2.6 m/s or higher, no. (%) | 227 | 22 (10) | 143 | 19 (13) | .3 |
| Hemoglobin g/L† | 235 | 91 (89-93) | 147 | 97 (94-99) | .002 |
| Mean corpuscular volume, fL† | 230 | 81 (79-82) | 146 | 92 (90-93) | <.001 |
| White blood cells, ×109/L† | 230 | 10.7 (10.2-11.2) | 143 | 8.8 (8.2-9.5) | .001 |
| Absolute neutrophil count, ×109/L | 229 | 5.2 (4.8-5.5) | 145 | 4.2 (3.7-4.6) | .00 |
| Platelets, ×109/L† | 230 | 384 (364-408) | 146 | 361 (331-388) | .2 |
| Reticulocytes, ×109/L† | 227 | 240 (220-259) | 146 | 198 (174-224) | .026 |
| Lactate dehydrogenase, U/L† | 219 | 403 (380-424) | 136 | 365 (336-391) | .070 |
| Aspartate aminotransferase, U/L† | 232 | 42 (40-44) | 149 | 36 (33-39) | .006 |
| Total bilirubin, mg/dL† | 232 | 2.4 (2.2-2.6) | 149 | 2.0 (1.8-2.2) | .034 |
| Hemolytic component‡ | 209 | 0.32 (0.12-0.52) | 133 | −0.36 (−0.63-−0.08) | .001 |
| Hemoglobin F, %† | 121 | 9 (7-10) | 76 | 13 (11-15) | <.001 |
| Hemoglobin F 8% or higher, no. (%) | 121 | 55 (45) | 76 | 56 (74) | <.001 |
| Erythropoietin, IU/L§ | 227 | 48 (44-52) | 143 | 59 (52-66) | .012 |
| . | Not on hydroxyurea . | Hydroxyurea treatment . | P* . | ||
|---|---|---|---|---|---|
| n . | Result . | n . | Result . | ||
| Age, y | 247 | 11 (10-12) | 150 | 13 (12-14) | <.001 |
| Female sex, no. (%) | 247 | 123 (50) | 150 | 67 (45) | .3 |
| Severe sickling phenotype, hemoglobin SS, Sβ0 thalassemia, or SDLA, no. (%) | 244 | 171 (70) | 149 | 127 (85) | .001 |
| Oxygen saturation, %† | 233 | 97 (97-98) | 144 | 98 (98-99) | .001 |
| Change in oxygen saturation during 6-minute walk, %† | 183 | 0 (−1-0) | 132 | 0 (−1-0) | .6 |
| Tricuspid regurgitation velocity, m/s† | 227 | 2.3 (2.2-2.3) | 143 | 2.3 (2.2-2.3) | .5 |
| Tricuspid regurgitation velocity, 2.5 m/s or higher, no. (%) | 227 | 47 (21) | 143 | 33 (23) | .6 |
| Tricuspid regurgitation velocity, 2.6 m/s or higher, no. (%) | 227 | 22 (10) | 143 | 19 (13) | .3 |
| Hemoglobin g/L† | 235 | 91 (89-93) | 147 | 97 (94-99) | .002 |
| Mean corpuscular volume, fL† | 230 | 81 (79-82) | 146 | 92 (90-93) | <.001 |
| White blood cells, ×109/L† | 230 | 10.7 (10.2-11.2) | 143 | 8.8 (8.2-9.5) | .001 |
| Absolute neutrophil count, ×109/L | 229 | 5.2 (4.8-5.5) | 145 | 4.2 (3.7-4.6) | .00 |
| Platelets, ×109/L† | 230 | 384 (364-408) | 146 | 361 (331-388) | .2 |
| Reticulocytes, ×109/L† | 227 | 240 (220-259) | 146 | 198 (174-224) | .026 |
| Lactate dehydrogenase, U/L† | 219 | 403 (380-424) | 136 | 365 (336-391) | .070 |
| Aspartate aminotransferase, U/L† | 232 | 42 (40-44) | 149 | 36 (33-39) | .006 |
| Total bilirubin, mg/dL† | 232 | 2.4 (2.2-2.6) | 149 | 2.0 (1.8-2.2) | .034 |
| Hemolytic component‡ | 209 | 0.32 (0.12-0.52) | 133 | −0.36 (−0.63-−0.08) | .001 |
| Hemoglobin F, %† | 121 | 9 (7-10) | 76 | 13 (11-15) | <.001 |
| Hemoglobin F 8% or higher, no. (%) | 121 | 55 (45) | 76 | 56 (74) | <.001 |
| Erythropoietin, IU/L§ | 227 | 48 (44-52) | 143 | 59 (52-66) | .012 |
Results are mean (95% confidence interval [CI] of mean) unless otherwise indicated.
Comparison of patients on hydroxyurea with those not on hydroxyurea.
Adjusted for sickling phenotype, age, sex, site, and chronic transfusion program.
Adjusted for sickling phenotype, sex, site, and chronic transfusion program.
Adjusted for sickling phenotype, age, sex, site, hemoglobin concentration, and chronic transfusion program.