J Hematol

Journal of Hematology, ISSN 1927-1212 print, 1927-1220 online, Open Access

Article copyright, the authors; Journal compilation copyright, J Hematol and Elmer Press Inc

Journal website https://www.thejh.org

Original Article

Volume 11, Number 3, June 2022, pages 92-108

Hematological, Biochemical Properties, and Clinical Correlates of Hemoglobin S Variant Disorder: A New Insight Into Sickle Cell Trait

Figure 1. Comparison of characteristics of anemia between SCT subjects and SCD patients. Bar graphs show the percentages of Hb values (g/dL) (a), RDW value (b), the RBC count (× 10⁶/L) (c), RBC volume (MCV, fL) (d) and chromicity (MCHC, g/dL) (e). SCT: sickle cell trait; SCD: sickle cell disease; Hb: hemoglobin; RDW: red cell distribution width; RBC: red blood cell; MCV: mean corpuscular volume; MCHC: mean corpuscular hemoglobin concentration.

Figure 2. Receiver operating characteristic curves for discriminating cases with Hb S variant (group 1) from healthy controls by: (a) RDW, RDWI and Mentzer index, (b) GK, EF and SLI, (c) SI, RI and EI, and (d) Sir I and HH. Hb: hemoglobin; RDW: red cell distribution width; RDWI: red cell distribution width index; GK: Green and King index; EF: England and Frazer index; SL: Shine and Lal index; SI: Srivastava index; RI: Ricerca index; EI: Ehsani index; Sir I: Sirdah index; HH: Huber-Herklotz index.

Figure 3. Receiver operating characteristic curves for discriminating patients with SCD from subjects with SCT by: (a) Hb, MCHC and Hct, (b) Hb A, Hb A2, Hb F and Hb S, (c) RDW, RDWI and Mentzer index, (d) GK, EF and SL, (e) SI, RI and EI, and (f) Sir I and HH. SCT: sickle cell trait; SCD: sickle cell disease; Hb: hemoglobin; MCHC: mean corpuscular hemoglobin concentration; Hct: hematocrit; RDW: red cell distribution width; RDWI: red cell distribution width index; GK: Green and King index; EF: England and Frazer index; SL: Shine and Lal index; SI: Srivastava index; RI: Ricerca index; EI: Ehsani index; Sir I: Sirdah index; HH: Huber-Herklotz index.

Figure 4. I: Schematic box plots representing the correlations of RDW, RDWI, MI and GKI results with hematological parameters among hemoglobin S variant cases. First, correlation between RDW and (a) Hb levels, (b) Hb F, (c) Hb S, (d) reticulocyte count; second, correlation between RDWI and (e) Hb levels, (f) Hb F, (g) Hb S, (h) reticulocyte count; third, correlation between Mentzer index and (i) Hb levels, (j) Hb F, (k) Hb S, (l) reticulocyte count; fourth, correlation between GK and (m) Hb levels, (n) Hb F, (o) Hb S, (p) reticulocyte count. II: Schematic box plots representing the correlations of (a-d) EF, (e-h) SL, (i-l) SI and (m-p) RI results with hematological parameters among hemoglobin S variant cases. Correlated as indicated in the figure. III: Schematic box plots representing the correlations of (a-d) EI, (e-h) Sir I and (i-l) HH results with hematological parameters among hemoglobin S variant cases. Correlated as indicated in the figure. IV: Schematic box plots representing correlations of some hematological parameters (a-f) among hemoglobin S variant cases. RDW: red blood cell distribution width; RDWI: red blood cell distribution width index; MI: Mentzer index; GKI: Green and King index; EF: England and Frazer index; SL: Shine and Lal index; SI: Srivastava index; RI: Ricerca index; EI: Ehsani index; Sir I: Sirdah index; HH: Huber-Herklotz index. r: Spearman rank correlation coefficient; P: P value.

Figure 6. Diagnostic algorithm for identification of SCD and SCT. SCT: sickle cell trait; SCD: sickle cell disease; HHA: hereditary hemolytic anemia; CBC: complete blood cell count; PBS: peripheral blood smear; AIHA: autoimmune hemolytic anemia; MAHA: microangiopathic hemolytic anemia; TTP: thrombotic thrombocytopenic purpura; HUS: hemolytic uremic syndrome; PNH: paroxysmal nocturnal hemoglobinuria.

**Table 1.** Demographic, Clinical and Hematological Characteristics of Studied Groups
Variable, n (%)	Hb S variant (group 1) (n = 55)	Controls (group 2) (n = 60)	P- value	SCD (group 1a) (n = 24)	SCT (group 1b) (n = 31)	P-value
P value was calculated with unpaired sample t-test. *P value was calculated with the Mann-Whitney test. ^#P value was calculated with the χ² test. P value < 0.05 was considered significant. SCD: sickle cell disease; SCT: sickle cell trait; SD: standard deviation; CBC: complete blood cell count; WBC: white blood cell; RBC: red blood cell; Hb: hemoglobin; MCV: mean corpuscular volume; MCH: mean corpuscular hemoglobin; MCHC: mean corpuscular hemoglobin concentration; Hct: hematocrit; MI: Mentzer index; RDW: red cell distribution width; RDWI: red cell distribution width index; GK: Green and King index; EF: England and Fraser index; SL: Shine and Lal index; SI: Srivastava index; RI: Ricerca index; EI: Ehsani index; Sir I: Sirdah index; HH: Huber-Herklotz index.
Age (years)			0.796			0.041
Mean ± SD	26.35 ± 9. 85	25.93 ± 11.77		25.96 ± 10.31	30.71 ± 9.73
Median	26	27		22	29
Range	18 - 52	18 - 45		18 - 48	18 - 52
Gender			0.193^#
Male	31 (56.4)	26 (43.3)		14 (58.3)	17 (54.8)	0.421
Female	24 (43.6)	34 (56.7)		10 (41.7)	14 (45.2)
Residence			0.074^#			0.863^#
Assiut	18 (32.7)	21 (35)		9 (37.5)	9 (41.9)
El Minia	1 (1.8)	4 (6.7)		1 (4.2)	0 (0.0)
Sohag	12 (21.8)	27 (45)		6 (25)	6 (35.5)
Qena	8 (14.5)	5 (8.3)		1 (4.2)	7 (0.0)
Luxor	2 (3.6)	0 (0.0)		1 (4.2)	1 (3.2)
Aswan	3 (5.5)	1 (1.7)		1 (4.1)	2 (3.2)
Red Sea	5 (9.1)	2 (3.3)		2 (8.3)	3 (6.5)
New Valley	6 (10.9)	0 (0.0)		3 (12.5)	3 (3.2)
Clinical presentation						0.000^#
Acute hemolysis	11 (20)			9 (37.5)	2 (6.4)
Painful crisis	9 (16.3)			8 (33.3)	1 (3.2)
Acute abdomen	4 (7.3)			4 (16.3)	0 (0)
Anemic manifestations	19 (34.5)			6 (25)	1 (3.2)
Jaundice	4 (7.2)			3 (12.5)	1 (3.2)
Acute chest syndrome	2 (3.6)			2 (8.3)	0 (0)
Obstructive jaundice	7 (12.7)			6 (25)	1 (3.2)
Accidental discovery	15 (27.2)			0 (0.0)	25 (80.6)
Nephropathy	3 (5.4)			2 (8.3)	1 (3.2)
Aplastic crisis	2 (3.6)			2 (8.3)	0 (0)
CBC
WBCs (× 10³/L)	7.72 ± 4.34	7.33 ± 1.75	0.163	8.83 ± 5.30	6.86 ± 3.25	0.502
RBCs (× 10⁶/L)	5.01 ± 4.93	5.92 ± 0.53	< 0.001	3.78 ± 1.31	5.96 ± 6.34	0.050
Hb (g/dL)	10.65 ± 3.31	14.22 ± 1.54	< 0.001	9.10 ± 2.20	11.85 ± 3.55	< 0.001
MCV (fL)	74.67 ± 17.79	85.72 ± 4.32	< 0.001	76.48 ± 9.86	73.27 ± 22.14	0.830
MCH (pg)	25.10 ± 5.43	28.27 ± 1.20	< 0.001	26.31 ± 4.59	24.17 ± 5.91	0.391
MCHC (g/dL)	36.21 ± 10.61	32.59 ± 1.26	0.518	31.29 ± 2.14	40.02 ± 12.84	< 0.001
Hct (%)	35.42 ± 11.77	43.82 ± 3.03	< 0.001	27.23 ± 3.84	41.76 ± 11.96	< 0.001
Reticulocytes (%)	3.74 ± 2.54	0.9 ± 0.37	< 0.001	4.72 ± 3.12	2.97 ± 1.67	0.045
Platelets (× 10³/L)	300.67 ± 93.84	316.73 ± 60.11	0.149	316.13 ± 82.53	300.67 ± 93.84	0.247
Targeted indices
MI	20.56 ± 11.14	16.37 ± 2.03	0.046	23.37 ± 10.91	18.09 ± 3.11	0.086
RDW (%)	17.01 ± 3.86	13.26 ± 0.80	< 0.001	17.01 ± 3.86	16.19 ± 4.22	0.030
RDWI	353.43 ± 24.80	216.71 ± 26.56	< 0.001	424.99 ± 201.77	298.03 ± 229.09	0.040
GK	108.37 ± 63.09	69.19 ± 8.72	0.260	127 ± 55.91	93.20 ± 6.49	0.009
EF	15.5 ± 22.30	5.94 ± 8.26	0.076	23.79 ± 11.9	9.13 ± 22.67	0.008
SL	1,569.90 ± 656.78	2,089.21 ± 280.90	< 0.001	1,608.6 ± 638.10	1,539.8 ± 679.80	0.773
SI	6.90 ± 3.54	5.39 ± 0.60	0.023	8.03 ± 3.94	6.01 ± 2.96	0.017
RI	4.81 ± 2.55	2.52 ± 0.28	< 0.001	5.43 ± 2.25	4.32 ± 2.68	0.018
EI	36.06 ± 19.90	32.77 ± 7.34	0.799	38.60 ± 20.46	34.09 ± 19.56	0.164
Sir I	40.59 ± 17.11	37.78 ± 5.87	1.000	45.39 ± 15.45	36.88 ± 17.64	0.018
HH	28.90 ± 9.29	20.40 ± 1.26	< 0.001	32.66 ± 8.64	26.00 ± 8.85	0.003

Table 1. Demographic, Clinical and Hematological Characteristics of Studied Groups

Variable, n (%)

Hb S variant (group 1) (n = 55)

Controls (group 2) (n = 60)

P- value

SCD (group 1a) (n = 24)

SCT (group 1b) (n = 31)

P-value

P value was calculated with unpaired sample t-test. *P value was calculated with the Mann-Whitney test. ^#P value was calculated with the χ² test. P value < 0.05 was considered significant. SCD: sickle cell disease; SCT: sickle cell trait; SD: standard deviation; CBC: complete blood cell count; WBC: white blood cell; RBC: red blood cell; Hb: hemoglobin; MCV: mean corpuscular volume; MCH: mean corpuscular hemoglobin; MCHC: mean corpuscular hemoglobin concentration; Hct: hematocrit; MI: Mentzer index; RDW: red cell distribution width; RDWI: red cell distribution width index; GK: Green and King index; EF: England and Fraser index; SL: Shine and Lal index; SI: Srivastava index; RI: Ricerca index; EI: Ehsani index; Sir I: Sirdah index; HH: Huber-Herklotz index.

Age (years)

0.796

0.041

Mean ± SD

26.35 ± 9. 85

25.93 ± 11.77

25.96 ± 10.31

30.71 ± 9.73

Median

Range

18 - 52

18 - 45

18 - 48

18 - 52

Gender

0.193^#

Male

31 (56.4)

26 (43.3)

14 (58.3)

17 (54.8)

0.421

Female

24 (43.6)

34 (56.7)

10 (41.7)

14 (45.2)

Residence

0.074^#

0.863^#

Assiut

18 (32.7)

21 (35)

9 (37.5)

9 (41.9)

El Minia

1 (1.8)

4 (6.7)

1 (4.2)

0 (0.0)

Sohag

12 (21.8)

27 (45)

6 (25)

6 (35.5)

Qena

8 (14.5)

5 (8.3)

1 (4.2)

7 (0.0)

Luxor

2 (3.6)

0 (0.0)

1 (4.2)

1 (3.2)

Aswan

3 (5.5)

1 (1.7)

1 (4.1)

2 (3.2)

Red Sea

5 (9.1)

2 (3.3)

2 (8.3)

3 (6.5)

New Valley

6 (10.9)

0 (0.0)

3 (12.5)

3 (3.2)

Clinical presentation

0.000^#

Acute hemolysis

11 (20)

9 (37.5)

2 (6.4)

Painful crisis

9 (16.3)

8 (33.3)

1 (3.2)

Acute abdomen

4 (7.3)

4 (16.3)

0 (0)

Anemic manifestations

19 (34.5)

6 (25)

1 (3.2)

Jaundice

4 (7.2)

3 (12.5)

1 (3.2)

Acute chest syndrome

2 (3.6)

2 (8.3)

0 (0)

Obstructive jaundice

7 (12.7)

6 (25)

1 (3.2)

Accidental discovery

15 (27.2)

0 (0.0)

25 (80.6)

Nephropathy

3 (5.4)

2 (8.3)

1 (3.2)

Aplastic crisis

2 (3.6)

2 (8.3)

0 (0)

CBC

WBCs (× 10³/L)

7.72 ± 4.34

7.33 ± 1.75

0.163

8.83 ± 5.30

6.86 ± 3.25

0.502

RBCs (× 10⁶/L)

5.01 ± 4.93

5.92 ± 0.53

< 0.001

3.78 ± 1.31

5.96 ± 6.34

0.050

Hb (g/dL)

10.65 ± 3.31

14.22 ± 1.54

< 0.001

9.10 ± 2.20

11.85 ± 3.55

< 0.001

MCV (fL)

74.67 ± 17.79

85.72 ± 4.32

< 0.001

76.48 ± 9.86

73.27 ± 22.14

0.830

MCH (pg)

25.10 ± 5.43

28.27 ± 1.20

< 0.001

26.31 ± 4.59

24.17 ± 5.91

0.391

MCHC (g/dL)

36.21 ± 10.61

32.59 ± 1.26

0.518

31.29 ± 2.14

40.02 ± 12.84

< 0.001

Hct (%)

35.42 ± 11.77

43.82 ± 3.03

< 0.001

27.23 ± 3.84

41.76 ± 11.96

< 0.001

Reticulocytes (%)

3.74 ± 2.54

0.9 ± 0.37

< 0.001

4.72 ± 3.12

2.97 ± 1.67

0.045

Platelets (× 10³/L)

300.67 ± 93.84

316.73 ± 60.11

0.149

316.13 ± 82.53

300.67 ± 93.84

0.247

Targeted indices

20.56 ± 11.14

16.37 ± 2.03

0.046

23.37 ± 10.91

18.09 ± 3.11

0.086

RDW (%)

17.01 ± 3.86

13.26 ± 0.80

< 0.001

17.01 ± 3.86

16.19 ± 4.22

0.030

RDWI

353.43 ± 24.80

216.71 ± 26.56

< 0.001

424.99 ± 201.77

298.03 ± 229.09

0.040

108.37 ± 63.09

69.19 ± 8.72

0.260

127 ± 55.91

93.20 ± 6.49

0.009

15.5 ± 22.30

5.94 ± 8.26

0.076

23.79 ± 11.9

9.13 ± 22.67

0.008

1,569.90 ± 656.78

2,089.21 ± 280.90

< 0.001

1,608.6 ± 638.10

1,539.8 ± 679.80

0.773

6.90 ± 3.54

5.39 ± 0.60

0.023

8.03 ± 3.94

6.01 ± 2.96

0.017

4.81 ± 2.55

2.52 ± 0.28

< 0.001

5.43 ± 2.25

4.32 ± 2.68

0.018

36.06 ± 19.90

32.77 ± 7.34

0.799

38.60 ± 20.46

34.09 ± 19.56

0.164

Sir I

40.59 ± 17.11

37.78 ± 5.87

1.000

45.39 ± 15.45

36.88 ± 17.64

0.018

28.90 ± 9.29

20.40 ± 1.26

< 0.001

32.66 ± 8.64

26.00 ± 8.85

0.003

**Table 2.** T-Test Results of Hematological Parameters of SCT Subjects and Control Group
	Participant group	Mean	SD	P value
P value was calculated with unpaired sample t-test. SCT: sickle cell trait; SD: standard deviation; WBC: white blood cell; RBCs: red blood cells; Hb: hemoglobin; MCV: mean corpuscular volume; MCH: mean corpuscular hemoglobin; MCHC: mean corpuscular hemoglobin concentration; Hct: hematocrit; MI: Mentzer index; RDW: red cell distribution width; RDWI: red cell distribution width index; GK: Green and King index; EF: England and Fraser index; SL: Shine and Lal index; SI: Srivastava index; RI: Ricerca index; EI: Ehsani index; Sir I: Sirdah index; HH: Huber-Herklotz index.
WBCs (× 10³/L)	Controls	7.329	1.7476	0.138
	SCT	7.048	2.9781
RBCs (× 10⁶/L)	Controls	5.296	0.5288	< 0.001
	SCT	4.368	1.2013
Hb (g/dL)	Controls	14.218	1.5449	0.007
	SCT	12.174	3.0627
MCV (fL)	Controls	85.732	4.3223	< 0.001
	SCT	77.774	11.6808
MCH (pg)	Controls	28.273	1.2038	< 0.001
	SCT	24.168	5.9053
MCHC (g/dL)	Controls	32.592	1.2607	0.008
	SCT	40.023	12.8395
Platelets (× 10³/L)	Controls	316.73	60.106	0.027
	SCT	288.71	101.439
Hct (%)	Controls	43.82	3.037	0.805
	SCT	40.44	9.655
Reticulocytes (%)	Controls	0.873	0.3654	< 0.001
	SCT	2.974	1.6733
Mentzer index	Controls	16.3668	2.02790	0.779
	SCT	20.3172	10.53331
RDW index	Controls	216.71	26.55909	0.49
	SCT	345.52	246.46697
RDW	Controls	13.2650	0.80398	0.002
	SCT	16.1903	4.22164
GK	Controls	69.1987	8.71872	0.514
	SCT	93.2031	64.98447
EF	Controls	5.9440	8.26077	0.233
	SCT	9.1348	22.67161
SL	Controls	2,089.21	280.97225	< 0.001
	SCT	1,539.93	679.80101
SI	Controls	5.3922	0.60189	0.763
	SCT	6.0194	2.96136
RI	Controls	2.5274	0.27603	< 0.001
	SCT	4.3260	2.68780
EI	Controls	32.7717	7.34526	0.293
	SCT	34.0903	19.56032
Sir I	Controls	37.7807	5.87379	0.016
	SCT	36.8832	17.64508
HH	Controls	20.4038	1.25761	0.001
	SCT	26.0023	8.85158

Table 2. T-Test Results of Hematological Parameters of SCT Subjects and Control Group

Participant group

Mean

P value

P value was calculated with unpaired sample t-test. SCT: sickle cell trait; SD: standard deviation; WBC: white blood cell; RBCs: red blood cells; Hb: hemoglobin; MCV: mean corpuscular volume; MCH: mean corpuscular hemoglobin; MCHC: mean corpuscular hemoglobin concentration; Hct: hematocrit; MI: Mentzer index; RDW: red cell distribution width; RDWI: red cell distribution width index; GK: Green and King index; EF: England and Fraser index; SL: Shine and Lal index; SI: Srivastava index; RI: Ricerca index; EI: Ehsani index; Sir I: Sirdah index; HH: Huber-Herklotz index.

WBCs (× 10³/L)

Controls

7.329

1.7476

0.138

SCT

7.048

2.9781

RBCs (× 10⁶/L)

Controls

5.296

0.5288

< 0.001

SCT

4.368

1.2013

Hb (g/dL)

Controls

14.218

1.5449

0.007

SCT

12.174

3.0627

MCV (fL)

Controls

85.732

4.3223

< 0.001

SCT

77.774

11.6808

MCH (pg)

Controls

28.273

1.2038

< 0.001

SCT

24.168

5.9053

MCHC (g/dL)

Controls

32.592

1.2607

0.008

SCT

40.023

12.8395

Platelets (× 10³/L)

Controls

316.73

60.106

0.027

SCT

288.71

101.439

Hct (%)

Controls

43.82

3.037

0.805

SCT

40.44

9.655

Reticulocytes (%)

Controls

0.873

0.3654

< 0.001

SCT

2.974

1.6733

Mentzer index

Controls

16.3668

2.02790

0.779

SCT

20.3172

10.53331

RDW index

Controls

216.71

26.55909

0.49

SCT

345.52

246.46697

RDW

Controls

13.2650

0.80398

0.002

SCT

16.1903

4.22164

Controls

69.1987

8.71872

0.514

SCT

93.2031

64.98447

Controls

5.9440

8.26077

0.233

SCT

9.1348

22.67161

Controls

2,089.21

280.97225

< 0.001

SCT

1,539.93

679.80101

Controls

5.3922

0.60189

0.763

SCT

6.0194

2.96136

Controls

2.5274

0.27603

< 0.001

SCT

4.3260

2.68780

Controls

32.7717

7.34526

0.293

SCT

34.0903

19.56032

Sir I

Controls

37.7807

5.87379

0.016

SCT

36.8832

17.64508

Controls

20.4038

1.25761

0.001

SCT

26.0023

8.85158

**Table 3.** Differences of Hemoglobin Fractions Between SCT Subjects and Control Group
Hb	Groups	Mean	Std. deviation	Std. error mean	P-value
Hb: hemoglobin; SCT: sickle cell trait.
Hb A	SCT	62.45	11.45	2.0570	0.000
	Controls	96.770	0.5097	0.0658
Hb A2	SCT	3.37	0.47	0.9562	0.009
	Controls	2.623	0.2619	0.0338
Hb F	SCT	1.400	2.35	0.4229	0.014
	Controls	0.61	0.51	0.0650
Hb S	SCT	34.78	10.59	1.9412	0.000
	Controls	0.000	0.0000	0.0000

Table 3. Differences of Hemoglobin Fractions Between SCT Subjects and Control Group

Groups

Mean

Std. deviation

Std. error mean

P-value

Hb: hemoglobin; SCT: sickle cell trait.

Hb A

SCT

62.45

11.45

2.0570

0.000

Controls

96.770

0.5097

0.0658

Hb A2

SCT

3.37

0.47

0.9562

0.009

Controls

2.623

0.2619

0.0338

Hb F

SCT

1.400

2.35

0.4229

0.014

Controls

0.61

0.51

0.0650

Hb S

SCT

34.78

10.59

1.9412

0.000

Controls

0.000

0.0000

**Table 4.** Receiver Operating Characteristic Curve Analysis Results and Predictive Values of Evaluated Indices for Differential Diagnosis of SCT Subjects and Control Group
Variable	AUC (95%)	Cut-off	Sens (%)	Spec (%)	PPV (%)	NPV (%)	% Correctly identified	YI	P value
AUC: area under the curve; Sens: sensitivity; Spec: specificity; PPV: positive-predictive value; NPV: negative-predictive value; YI: Youden’s index; SC: sickle cell; SCT: sickle cell trait; RBCs: red blood cell; Hb: hemoglobin; MCHC: mean corpuscular hemoglobin concentration; Hct: hematocrit; RDW: red blood cell distribution width; RDWI: red blood cell distribution width index; GK: Green and King index; EF: England and Frazer index; SL: Shine and Lal index; SI: Srivastava index; RI: Ricerca index; EI: Ehsani index; Sir I: Sirdah index; HH: Huber-Herklotz index.
MCHC	0.67 (0.52 - 0.81)	SCT > 33.5	61%	81%	63%	80%	75%	0.42	0.009
Retics (%)	0.98 (0.96 - 1.02)	SCT > 2%	70%	100%	100%	87%	66%	0.70	< 0.001
RDW (%)	0.70 (0.56 - 0.83)	SCT > 14%	54%	85%	65%	78%	74%	0.39	0.002
RDWI	0.63 (0.49 - 0.76)	SCT > 240%	54%	80%	59%	77%	71%	0.29	0.049
SL	0.82 (0.70 - 0.93)	SCT < 1,780	88%	71%	58%	76%	82%	0.59	< 0.001
RI	0.79 (0.68 - 0.90)	SCT > 2.8	68%	83%	68%	83%	78%	0.51	< 0.001
Sir I	0.35 (0.19 - 0.50)	SCT > 35	26%	52%	22%	58%	43%	-0.22	0.016
HH	0.71 (0.58 - 0.84)	SCT > 21.5	55%	78%	56%	77%	70%	0.33	0.001

Table 4. Receiver Operating Characteristic Curve Analysis Results and Predictive Values of Evaluated Indices for Differential Diagnosis of SCT Subjects and Control Group

Variable

AUC (95%)

Cut-off

Sens (%)

Spec (%)

PPV (%)

NPV (%)

% Correctly identified

P value

AUC: area under the curve; Sens: sensitivity; Spec: specificity; PPV: positive-predictive value; NPV: negative-predictive value; YI: Youden’s index; SC: sickle cell; SCT: sickle cell trait; RBCs: red blood cell; Hb: hemoglobin; MCHC: mean corpuscular hemoglobin concentration; Hct: hematocrit; RDW: red blood cell distribution width; RDWI: red blood cell distribution width index; GK: Green and King index; EF: England and Frazer index; SL: Shine and Lal index; SI: Srivastava index; RI: Ricerca index; EI: Ehsani index; Sir I: Sirdah index; HH: Huber-Herklotz index.

MCHC

0.67 (0.52 - 0.81)

SCT > 33.5

61%

81%

63%

80%

75%

0.42

0.009

Retics (%)

0.98 (0.96 - 1.02)

SCT > 2%

70%

100%

87%

66%

0.70

< 0.001

RDW (%)

0.70 (0.56 - 0.83)

SCT > 14%

54%

85%

65%

78%

74%

0.39

0.002

RDWI

0.63 (0.49 - 0.76)

SCT > 240%

54%

80%

59%

77%

71%

0.29

0.049

0.82 (0.70 - 0.93)

SCT < 1,780

88%

71%

58%

76%

82%

0.59

< 0.001

0.79 (0.68 - 0.90)

SCT > 2.8

68%

83%

68%

83%

78%

0.51

< 0.001

Sir I

0.35 (0.19 - 0.50)

SCT > 35

26%

52%

22%

58%

43%

-0.22

0.016

0.71 (0.58 - 0.84)

SCT > 21.5

55%

78%

56%

77%

70%

0.33

0.001