Table 5 Possible sources of heterogeneity of meta-analysis (results of subgroup analysis and meta-regression analysis)

Setting

ICU

10

0.85 (0.81–0.88)

0.82 (0.79–0.85)

4.73 (3.41–6.55)

0.19 (0.12–0.31)

29.05 (14.29–59.02)

0.91

–0.96

1.16

0.45

0.38 (0.02–9.57)

ER

2

0.67 (0.59–0.75)

0.63 (0.52–0.73)

2.56 (0.48–13.65)

0.35 (0.05–2.34)

7.57 (0.27–216.18)

–

Design

Prospective

7

0.77 (0.73–0.82)

0.76 (0.71–0.80)

3.41 (1.98–5.85)

0.24 (0.11–0.50)

15.00 (4.58–49.14)

0.84

0.16

0.80

0.85

1.18 (0.13–10.85)

Nonprospective

5

0.85 (0.79–0.90)

0.87 (0.82–0.90)

6.40 (3.94–10.40)

0.19 (0.11–0.32)

45.65 (18.15–114.83)

0.94

Number of cases

≥100

7

0.87 (0.74–0.82)

0.76 (0.72–0.79)

3.20 (1.95–5.24)

0.24 (0.12–0.49)

13.62 (4.53–40.98)

0.82

1.33

0.84

0.19

3.77 (0.37–38.63)

<100

5

0.85 (0.78–0.91)

0.90 (0.85–0.94)

7.85(5.24–11.74)

0.18 (0.11–0.30)

58.18 (27.63–122.49)

0.95

NGAL test method

ELISA

9

0.81 (0.77–0.84)

0.81 (0.77–0.84)

4.79 (2.76–8.32)

0.18 (0.09–0.35)

28.07 (9.47–83.18)

0.91

0.51

1.01

0.64

1.66 (0.10–26.97)

Non-ELISA

3

0.78 (0.69–0.86)

0.77 (0.70–0.83)

3.16 (1.46–6.82)

0.31 (0.12–0.76)

15.56 (2.42–100.09)

0.86

Location

Asia

9

0.88 (0.84–0.91)

0.83 (0.79–0.86)

5.01 (3.87–6.49)

0.17 (0.12–0.22)

33.05 (20.72–52.72)

0.92

–1.23

1.30

0.40

0.29 (0.01–10.88)

Others

3

0.63 (0.55–0.70)

0.69 (0.61–0.76)

1.99 (0.83–4.76)

0.56 (0.34–0.93)

4.34 (0.96–19.62)

0.64

Language

English

5

0.74 (0.68–0.79)

0.71 (0.65–0.76)

2.51 (1.38–4.57)

0.34 (0.17–0.69)

9.36 (2.40–36.54)

0.83

0.60

1.04

0.59

1.82 (0.10–32.62.)

Chinese

7

0.87 (0.83–0.91)

0.86 (0.82–0.89)

5.77 (4.56–7.30)

0.16 (0.10–0.24)

41.64 (22.82–75.97)

0.93