Table 2 Participant characteristics of the training and test set.

From: Predicting skeletal fluorosis severity using machine learning across diverse fluoride-exposed populations in China

 

Training sets (n = 917)

Test sets (n = 392)

 

SF (Mild)

(n = 600)

SF (Moderate/Severe) (n = 317)

P value

(Inner)

SF (Mild)

(n = 254)

SF (Moderate/Severe)

(n = 138)

P value

(Inner)

P value

(External)

Demographic data

 Gender

  

0.15

  

0.09

0.07

  Male

241 (26.3%)

112 (12.2%)

 

120 (30.6%)

53 (13.5%)

  

  Female

359 (39.2%)

205 (22.4%)

 

134 (34.2%)

85 (21.7%)

  

 Age

58.0 (51.0, 67.0)

68.0 (59.0, 73.0)

< 0.001

59.0 (52.0, 66.0)

65.0 (58.0, 72.0)

< 0.001

0.79

 Living area

  

< 0.001

  

< 0.001

0.98

  Guizhou

130 (14.2%)

138 (15.1%)

 

57 (14.5%)

59 (15.1%)

  

  Shanxi

194 (21.2%)

132 (14.4%)

 

86 (21.9%)

51 (13.0%)

  

  Sichuan

276 (30.1%)

47 (5.10%)

 

111 (28.3%)

28 (7.10%)

  

 Nationality

  

< 0.001

  

0.01

0.34

  Han ethnicity

289 (31.5%)

311 (33.9%)

 

123 (31.4%)

131 (33.4%)

  

  Minority

224 (24.4%)

93 (10.1%)

 

85 (21.7%)

53 (13.5%)

  

 Educational level

  

< 0.001

  

0.009

0.72

  Illiteracy

160 (17.5%)

35 (3.80%)

 

69 (17.6%)

22 (5.60%)

  

  Elementary school

296 (32.3%)

177 (19.3%)

 

113 (28.8%)

82 (20.9%)

  

  Middle school and above

144 (15.7%)

105 (11.5%)

 

72 (18.4%)

34 (8.70%)

  

 Annual income (Yuan)

  

< 0.001

  

0.003

0.46

  Less than 20,000

285 (31.1%)

315 (34.4%)

 

110 (28.1%)

114 (36.7%)

  

  More than 20,000

194 (21.2%)

123 (13.4%)

 

86 (21.9%)

52 (13.3%)

  

 Average sleep time (hours)

8.00 (7.00, 9.00)

7.00 (6.00, 8.00)

< 0.001

8.00 (7.00, 9.00)

8.00 (6.00, 9.00)

0.006

0.33

 Body mass index

25.4 (23.2, 28.0)

24.7 (22.5, 27.3)

0.01

25.6 (23.2, 27.9)

24.9 (22.4, 27.4)

0.06

0.91

 Bone density

1529 (1511, 1550)

1519 (1505, 1535)

< 0.001

1531 (1511, 1557)

1517 (1505, 1533)

< 0.001

0.59

 Bone mass index

48.3 (43.9, 53.6)

44.8 (41.1, 50.2)

< 0.001

48.6 (44.2, 55.4)

45.7 (41.9, 49.7)

< 0.001

0.17

 Bone mass

4.80 (4.40, 5.20)

4.60 (4.20, 5.20)

< 0.001

5.00 (4.40, 5.40)

4.60 (4.20, 5.00)

0.002

0.31

Orthopedic surgical evaluation

 Elbow function

  

< 0.001

  

< 0.001

0.10

  No limitation of movement

463 (50.5%)

137 (14.9%)

 

181 (46.2%)

73 (18.6%)

  

  Significant limitation of movement

167 (18.2%)

150 (16.4%)

 

70 (17.9%)

68 (17.4%)

  

 Spinal function

  

< 0.001

  

< 0.001

0.43

  No limitation of movement

425 (46.4%)

175 (19.1%)

 

174 (44.4%)

80 (20.4%)

  

  Significant limitation of movement

146 (15.9%)

171 (18.7%)

 

61 (15.6%)

77 (19.6%)

  

 Knee function

  

< 0.001

  

< 0.001

0.32

  No limitation of movement

436 (47.6%)

164 (17.9%)

 

189 (48.2%)

65 (16.6%)

  

  Significant limitation of movement

84 (9.20%)

234 (25.4%)

 

45 (11.5%)

93 (23.7%)

  

 Shoulder function

  

< 0.001

  

< 0.001

0.07

  No limitation of movement

539 (58.8%)

61 (6.70%)

 

219 (55.9%)

35 (8.90%)

  

  Significant limitation of movement

204 (22.3%)

113 (12.3%)

 

75 (19.1%)

63 (16.1%)

  

 Pain level score

3.00 (2.00, 4.00 )

5.00 (4.00, 6.00 )

< 0.001

3.00 (2.00, 4.00)

5.00 (4.00, 6.00)

< 0.001

0.93

Bone metabolism indicators

 PTH (pg/mL)

52.8 (40.8, 67.6)

48.3 (38.3, 64.1)

0.002

51.6 (38.7, 67.0)

50.4 (41.0, 65.4)

0.50

0.72

 Osteocalcin (ng/mL)

24.9 (19.2, 33.1)

28.1 (21.9, 35.7)

0.003

24.5 (18.0, 30.7)

27.1 (21.5, 34.3)

0.004

0.05

 PINP (µg/L)

77.5 (56.0, 96.3)

77.8 (61.6, 98.2)

0.02

66.5 (52.1, 88.0)

74.1 (56.9, 96.3)

0.01

0.03

 β-CrossLaps (ng/mL)

0.450 (0.338, 0.600)

0.520 (0.390, 0.650)

0.001

0.425 (0.320, 0.570)

0.530 (0.360, 0.670)

0.002

0.10

 Vitamin D (ng/mL)

23.1 (17.9, 29.1)

24.3 (19.2, 29.9)

0.02

23.0 (18.2, 29.0)

25.1 (19.2, 30.6)

0.06

0.64

Biochemical indicators

 Total bilirubin (µmol/L)

11.63 (7.20, 16.4)

10.0 (6.30, 14.4)

0.003

12.3 (6.72, 18.3)

10.3 (6.37, 14.0)

0.03

0.46

 Direct bilirubin (µmol/L)

2.93 (2.01, 4.10)

3.30 (2.45, 4.41)

0.001

3.10 (2.10, 4.26)

3.20 (2.25, 4.18)

0.20

0.99

 Urea (mmol/L)

5.11 (4.30, 6.20)

5.50 (4.80, 6.60)

< 0.001

5.29 (4.39, 6.42)

5.47 (4.65, 6.80)

0.03

0.59

 IBIL (µmol/L)

9.60 (5.10, 13.9)

7.60 (4.20, 11.0)

< 0.001

9.40 (5.20, 14.9)

7.25 (4.13, 10.2)

0.004

0.87

 Albumin (g/L)

44.4 (42.7, 46.0)

43.7 (41.9, 45.7)

0.007

44.4 (42.3, 46.1)

44.0 (41.8, 48.5)

0.19

0.69

 Urinary fluoride (mg/L)

1.26 (0.66, 2.61)

2.04 (1.11, 3.34)

< 0.001

1.33 (0.740, 2.91)

1.83 (0.922, 3.28)

0.01

0.47

 WBC (10^9/L)

5.89 (4.72, 6.94)

6.21 (5.30, 7.60)

< 0.001

6.19 (5.07, 7.30)

6.15 (5.1, 7.49)

0.50

0.07

 NEUT (10^9/L)

3.50 (2.68, 4.54)

3.86 (3.05, 5.01)

0.001

3.79 (2.86, 4.79)

3.81 (2.91, 5.37)

0.30

0.08

 RBC (10^12/L)

4.95 (4.52, 5.42)

4.65 (4.25, 5.00)

< 0.001

4.96 (4.52, 5.46)

4.64 (4.31, 4.97)

< 0.001

0.74

 HCT (%)

45.1 (41.3, 48.9)

42.7 (39.4, 46.2)

< 0.001

45.5 (41.1, 50.1)

43.2 (40.5, 47.4)

0.02

0.13

 MCV (fL)

91.8 (88.5, 94.9)

92.2 (89.5, 95.5)

0.03

91.9 (88.5, 94.8)

92.5 (89.7, 95.5)

0.06

0.79

 MCH (pg)

29.8 (28.4, 31.2)

30.4 (29.2, 31.8)

< 0.001

29.8 (28.4, 31.3)

30.5 (29.1, 31.9)

0.004

0.88

 MCHC (g/dL)

321 (316, 331)

329 (323, 336)

< 0.001

322 (316, 331)

328 (319, 334)

0.003

0.83

 PDW (fL)

11.4 (9.90, 15.6)

14.3 (10.8, 16.4)

< 0.001

11.3 (9.90, 15.9)

13.6 (10.7, 16.3)

0.006

0.64

 PCT (%)

0.240 (0.200, 0.280)

0.230 (0.190, 0.270)

0.01

0.250 (0.200, 0.290)

0.230 (0.200, 0.280)

0.10

0.45

 IL5 (pg/mL)

3.22 (2.41, 4.01)

2.90 (1.23, 3.86)

0.001

3.27 (2.49, 4.14)

2.63 (1.19, 3.68)

< 0.001

0.94

 IFNα (pg/mL)

2.48 (1.76, 3.03)

2.04 (0.930, 2.85)

< 0.001

2.46 (1.81, 3.09)

1.98 (0.898, 2.71)

< 0.001

0.86

 IL2 (pg/mL)

0.920 (0.660, 1.20)

0.840 (0.380, 1.15)

0.02

0.925 (0.670, 1.27)

0.760 (0.460, 1.15)

0.02

0.69

 IL1β (pg/mL)

1.83 (0.710, 4.48)

1.04 (0.180, 4.48)

< 0.001

1.88 (0.820, 4.48)

1.13 (0.210, 4.48)

0.002

0.81

 IFNγ (pg/mL)

4.36 (1.78, 7.27)

3.07 (0.840, 7.27)

0.006

4.13 (1.79, 7.75)

2.47 (0.618, 6.58)

0.002

0.85

 IL4 (pg/mL)

0.515 (0.270, 0.913)

0.570 (0.310, 1.04)

0.02

0.600 (0.320, 0.948)

0.520 (0.278, 0.855)

0.38

0.69

  1. Inner P values compare severity groups within the same dataset; External P values compare the training and test sets. All numerical values in this table are rounded to three significant digits to ensure consistent precision.