Table 2.

Selected red cell indices (mean, SD) in HbAS and HbAC with significance of difference from a normal AA phenotype

Phenotype (n)	Hb (g/dL)	Hct (L/L)	MCHC (g/dL)	RBC (× 1012/L)	MCV (fL)	MCH (pg)	lnRDW
Males
HbAA (5579)	14.47, 1.16	42.96, 3.47	33.72, 1.42	5.13, 0.44	83.96, 5.72	28.31, 2.32	13.68, 1.25
HbAS ( 632)	14.50, 1.09	42.79, 3.19	33.92, 1.49	5.26, 0.47	81.64, 5.67	27.70, 2.29	14.09, 1.32
Females	14.75, 1.14	42.96, 3.21	34.40, 1.78	5.46, 0.47	79.00, 6.26	27.09, 2.31	15.11, 1.48
HbAA (7219)	12.45, 1.24	37.34. 3.50	33.36, 1.56	4.51, 0.39	82.96, 7.04	27.70, 2.82	14.06, 1.98
HbAS ( 827)	12.51, 1.20	37.24, 3.40	33.61, 1.47	4.65, 0.40	80.39, 7.13	27.05, 2.80	14.48, 2.19
HbAC ( 301)	12.58, 1.27	36.91, 3.66	34.08, 1.80	4.80, 0.39	77.02, 6.93	26.27, 2.67	15.51, 2.07
Significance of phenotype differences – difference / (95%CI) / p value
Males
HbAS:HbAA	0.04 (0.05, 0.14) 0.35	-0.12 (-0.40, 0.16) 0.41	0.20 (0.08, 0.32)  <0.01	0.13 (0.10, 0.17)  <0.01	-2.30 (-2.77, -1.83)  <0.01	-0.60 (-0.79, -0.41)  <0.01	0.03 (0.02, 0.04)  <0.01
HbAC:HbAA	0.28 (0.13, 0.43)  <0.01	0.03 (-0.42, 0.48) 0.90	0.67 (0.48, 0.86)  <0.01	0.33 (0.28, 0.39)  <0.01	-4.95 (-5.72, -4.19)  <0.01	-1.22 (-1.53, -0.91)  <0.01	0.10 (0.09, 0.11)  <0.01
Females
HbAS:HbAA	0.06 (-0.03, 0.14) 0.22	-0.11 (-0.36, 0.14) 0.38	0.26 (0.15, 0.37)  <0.01	0.13 (0.11, 0.16)  <0.01	-2.58 (-3.09, -2.08)  <0.01	-0.64 (-0.84, -0.44)  <0.01	0.03 (0.02, 0.04)  <0.01
HbAC:HbAA	0.13 (-0.01, 0.28) 0.06	-0.41 (-0.81, -0.01) 0.04	0.73 (0.56, 0.91)  <0.01	0.29 (0.25, 0.34)  <0.01	-5.94 (-6.75, -5.13)  <0.01	-1.42 (-1.75, -1.10)  <0.01	0.10 (0.08, 0.11)  <0.01

RDW is skewed in distribution and log-transformed for the tests for difference. RDW-CV expressed in arbitrary units

SD = standard deviation; CI = confidence interval; diff = difference derived from the multilevel model adjusting for school effects