Table 4 Test characteristics of the high sensitivity, high positive predictive value (PPV), and balanced algorithms for classifying type 1 diabetes compared to the reference standard in the validation cohort, stratified by age at diagnosis. Sensitivity, specificity, PPV and negative predictive value (NPV) are percentages with 95% confidence intervals. Cohen’s kappa coefficient represents agreement after agreement due to chance is removed (1.0 indicates perfect agreement) [31]. The “Type 1 Proportion” columns refer to the percentage of people in the cohort with diabetes classified as type 1 using each algorithm (“Calculated”) and the reference standard (“True”)

41

280

2

4778

95.3 (84.2, 99.4)

94.5 (93.8, 95.1)

12.8 (9.3, 16.9)

100.0 (99.8, 100.0)

0.21

6.3

0.8

14

6

0

21

100.0 (76.8, 100.0)

77.8 (57.7, 91.4)

70.0 (45.7, 88.1)

100.0 (83.9, 100.0)

0.71

48.8

34.1

19

41

2

300

90.5 (69.6, 98.8)

88.0 (84.0, 91.2)

31.7 (20.3, 45.0)

99.3 (97.6, 99.9)

0.42

16.6

5.8

8

233

0

4457

100.0 (63.1, 100.0)

95.0 (94.4, 95.6)

3.3 (1.4, 6.4)

100.0 (99.9, 100.0)

0.06

5.1

0.2

16

0

27

5058

37.2 (23.0, 53.3)

100.0 (99.9, 100.0)

100.0 (79.4, 100.0)

99.5 (99.2, 99.6)

0.54

0.3

0.8

8

0

6

27

57.1 (28.9, 82.3)

100.0 (87.2, 100.0)

100.0 (63.1, 100.0)

81.8 (64.5, 93.0)

0.64

19.5

34.1

6

0

15

341

28.6 (11.3, 52.2)

100.0 (98.9, 100.0)

100.0 (54.1, 100.0)

95.8 (93.1, 97.6)

0.43

1.7

5.8

2

0

6

4690

25.0 (3.2, 65.1)

100.0 (99.9, 100.0)

100.0 (15.8, 100.0)

99.9 (99.7, 100.0)

0.40

0.0

0.2

28

9

15

5049

65.1 (49.1, 79.0)

99.8 (99.7, 99.9)

75.7 (58.8, 88.2)

99.7 (99.5, 99.8)

0.70

0.7

0.8

12

0

2

27

85.7 (57.2, 98.2)

100.0 (87.2, 100.0)

100.0 (73.5, 100.0)

93.1 (77.2, 99.2)

0.89

29.3

34.1

12

7

9

334

57.1 (34.0, 78.2)

97.9 (95.8, 99.2)

63.2 (38.4, 83.7)

97.4 (95.1, 98.8)

0.58

5.2

5.8

4

2

4

4688

50.0 (15.7, 84.3)

100.0 (99.8, 100.0)

66.7 (22.3, 95.7)

99.9 (99.8, 100.0)

0.57

0.1

0.2