Table 1.

Baseline demographic characteristics and DXA results for the SCCRIP BMD Cohort

VariableAll (N = 306)Female (n = 153)Male (n = 153)
School-age (n = 96 [31.4%])Adolescent (n = 210 [68.6%])School-age (n = 46 [30.1%])Adolescent (n = 107 [69.9%])School-age (n = 50 [32.7%)Adolescent (n = 103 [67.3%])
SCD genotype
 HbSS/Sβ0-thalassemia61 (63.5)136 (64.8)27 (58.7)67 (62.6)34 (68.0)69 (67.0)
 HbSC28 (29.2)52 (24.8)16 (34.8)30 (28.0)12 (24.0)22 (21.4)
 HbSβ+-thalassemia7 (7.3)22 (10.5)3 (6.5)10 (9.4)4 (8.0)12 (11.6)
Age at DXA, y7.2 ± 1.13*14.8 ± 2.16*7.0 ± 0.78*14.9 ± 2.16*7.4 ± 1.37*14.7 ± 2.17*
Race/ethnicity
 African American94 (97.9)210 (100.0)44 (95.6)107 (100)50 (100)103(100)
 Other2 (2.1)0 (0)2 (4.4)0 (0)0 (0)0 (0)
Hydroxyurea use
 No42 (43.8)83 (39.5)21 (45.6)44 (41.1)21 (42.0)39 (37.9)
 Yes54 (56.2)127 (60.5)25 (54.4)63 (58.9)29 (58.0)64 (62.1)
Chronic RBC transfusions
 No95 (99.0)202 (96.2)46 (100)101 (94.4)49 (98.0)101 (98.1)
 Yes1 (1.0)8 (3.8)0 (0)6 (5.6)1 (2.0)2 (1.9)
Height, cm122.2 ± 9.74*160.0 ± 11.53*120.7 ± 7.97*158.1 ± 8.51*123.5 ± 11.03*161.9 ± 13.77*
Height-for-age z scores−0.12 ± 1.07−0.21 ± 1.11−0.19 ± 0.96−0.14 ± 1.09−0.05 ± 1.17−0.29 ± 1.13
TBLH aBMD, g/cm20.58 ± 0.07*0.86 ± 0.11*0.57 ± 0.06*0.85 ± 0.09*0.59 ± 0.08*0.86 ± 0.14*
TBLH aBMD z score
 Normal73 (76.0)137 (65.2)35 (76.1)73 (68.2)38 (76.0)64 (62.1)
 Low23 (24.0)73 (34.8)11 (23.9)34 (31.8)12 (24.0)39 (37.9)
TBLH aBMD z score−1.14 ± 1.03*−1.60 ± 1.25*−1.07 ± 1.06*−1.54 ± 1.20*−1.20 ± 1.01*−1.65 ± 1.30*
TBLH Ht-aBMD z score
 Normal92 (95.8)*158 (75.2)*44 (95.6)*84 (78.5)*48 (96.0)*74 (71.8)*
 Low4 (4.2)*52 (24.8)*2 (4.4)*23 (21.5)*2 (4.0)*29 (28.2)*
TBLH Ht-aBMD z score−0.80 ± 0.69*−1.36 ± 1.05*−0.81 ± 0.72*−1.34 ± 1.02*−0.80 ± 0.67*−1.37 ± 1.08*
  • Data are presented as n (%) or mean ± standard deviation.

  • Hb, hemoglobin; RBC, red blood cell.

  • * P < .05 between school-age vs adolescent values.

  • Defined as ≥4 RBC transfusions per year.