Table 4.

Subgroup analysis.

Factors	Subgroup	Sensitivity (95%CI)	Specificity (95%CI)	+LR (95%CI)	–LR (95%CI)	DOR (95%CI)	AUC (95%CI)
All studies (27)		0.64 (0.59–0.73)	0.77 (0.71–0.83)	2.82 (2.10–3.78)	0.46 (0.36–0.61)	6.08 (3.63–10.18)	0.78 (0.74–0.81)
I2 (%)		86.47	93.64	77.92	87.21	100
Age	Adults (21)	0.64 (0.54–0.73)	0.76 (0.69–0.82)	2.69 (1.92–3.77)	0.47 (0.35–0.63)	5.75 (3.17–10.42)	0.77 (0.73–0.80)
	I2 (%)	85.25	94.34	79.64	87.50	100.00
	Pediatrics (5)	0.61 (0.31–0.84)	0.83 (0.66–0.92)	3.5 (1.98–6.18)	0.48 (0.25–0.93)	7.33 (2.86–18.78)	0.81 (0.78–0.85)
	I2 (%)	92.32	87.35	19.14	87.32	95.43
Predictive time	≤12 h (13)	0.69 (0.53–0.81)	0.73 (0.60–0.82)	2.51 (1.66–3.81)	0.43 (0.27–0.68)	5.87 (2.68–12.85)	0.77 (0.73–0.80)
	I2 (%)	82.62	92.44	76.58	88.54	100.00
	>12 h (13)	0.60 (0.47–0.71)	0.81 (0.75–0.86)	3.15 (2.15–4.62)	0.50 (0.36–0.69)	6.31 (3.21–12.39)	0.80 (0.76–0.83)
	I2 (%)	86.43	85.71	80.90	89.01	100
Obtaining specimen	Admission (6)	0.58 (0.36–0.77)	0.75 (0.68–0.81)	2.32 (1.83–2.94)	0.56 (0.36–0.87)	4.12 (2.17–7.81)	0.75 (0.71–0.79)
	I2 (%)	87.63	88.32	45.91	77.60	98.43
	Other times (20)	0.66 (0.56–0.76)	0.78 (0.70–0.85)	3.08 (2.07–4.57)	0.43 (0.31–0.59)	7.20 (3.69–14.04)	0.79 (0.75–0.82)
	I2 (%)	84.19	93.08	81.29	88.39	100.00
Patients population	Cardiac surgery (12)	0.62 (0.48–0.75)	0.73 (0.62–0.81)	2.29 (1.63–3.21)	0.52 (0.37–0.73)	4.42 (2.39–8.16)	0.74 (0.69–0.77)
	I2 (%)	76.37	92.57	56.00	81.94	100.00
	Other patients (14)	0.65 (0.52–0.77)	0.81 (0.73–0.87)	3.46 (2.16–5.52)	0.43 (0.29–0.63)	8.11 (3.64–18.10)	0.81 (0.77–0.84)
	I2 (%)	91.48	96.75	90.68	93.38	100
Publication date	Before 2009 (including 2009) (8)	0.51 (0.34–0.68)	0.78 (0.65–0.87)	2.30 (1.29–4.11)	0.63 (0.43–0.92)	3.65 (1.48–9.00)	0.71 (0.67–0.75)
	I2 (%)	81.52	84.26	22.39	83.32	99.99
	After 2009 (18)	0.69 (0.58–0.78)	0.77 (0.69–0.83)	2.99 (2.13–4.22)	0.41 (0.29–0.56)	7.39 (4.01–13.63)	0.80 (0.76–0.83)
	I2 (%)	88.58	95.65	87.44	90.04	100
AKI definition	Standardized definition (RIFLE, AKIN, KDIGO) (17)	0.69 (0.69–0.69)	0.78 (0.78–0.78)	3.09 (3.09–3.09)	0.39 (0.39–0.39)	7.81 (7.81–7.81)	0.80 (0.77–0.84)
	I2 (%)	89.90	94.23	85.98	90.19	100
	Non-standardized definition (9)	0.53 (0.39–0.67)	0.77 (0.65–0.86)	2.30 (1.43–3.68)	0.61 (0.45–0.83)	3.76 (1.82–7.77)	0.70 (0.66–0.74)
	I2 (%)	72.90	89.64	42.09	85.29	100
Continents	Asia (12)	0.74 (0.60–0.84)	0.79 (0.67–0.88)	3.56 (2.20–5.76)	0.33 (0.21–0.52)	10.81 (4.92–23.73)	0.83 (0.80–0.86)
	I2 (%)	82.22	94.66	88.19	85.65	100
	North America (11)	0.58 (0.45–0.70)	0.77 (0.70–0.83)	2.51 (1.18–3.36)	0.55 (0.41–0.72)	4.59 (2.73–7.72)	0.76 (0.72–0.79)
	I2 (%)	85.84	93.53	34.73	80.45	100
	Other (3)	0.43 (0.24–0.64)	0.67 (0.55–0.78)	1.29 (0.66–2.53)	0.86 (0.55–1.33)	1.51 (0.50–4.59)	0.60 (0.56–0.64)
	I2 (%)	79.84	89.55	72.25	84.56	99.61