Table 3 Sensitivity, specificity, positive predictive value, and negative predictive value of different tests of physical examination and hemodynamic parameters to detect AVF stenosis against duplex Doppler ultrasound (n=324)

	AUC (95%CI)	Sens (%)	Spec (%)	PPV (%)	NPV (%)
Physical examinations
Swollen fistula arm	0.59 (0.52–0.65)	16.87	92.23	48.28	72.06
Collateral veins in ipsilateral arm and chest wall	0.60 (0.54–0.65)	16.87	96.37	66.67	72.94
Arm elevation test	0.74 (0.67–0.81)	89.16	73.06	58.73	94
Pulse augmentation test	0.96 (0.92–1.00)	91.57	97.93	95	96.43
A combination of arm elevation and pulse augmentation test	0.87 (0.82–0.91)	100	73.06	61.48	100
Hemodynamic parameters
Qa<500 mL/min (brachial artery)	0.54 (0.47–0.62)	9.64	98.96	80	71.8
Qa<750 mL/min (brachial artery)	0.58 (0.51–0.66)	21.69	94.82	64.29	73.79
Qmin<500 mL/min	0.71 (0.63–0.78)	50.6	90.67	70	81.02
Pa>100 mmHg	0.55 (0.47–0.64)	72.29	50.26	38.46	80.83
Delta Pai-Pvi<0	0.59 (0.52–0.67)	26.51	80.31	36.67	71.76
VAPR>1.54	0.57 (0.48–0.65)	66.27	58.03	40.44	80
Access recirculation ratio≥5%	0.60 (0.53–0.68)	60.24	60.1	39.37	77.85
spKt/V<1.2	0.51 (0.43–0.58)	14.46	87.05	32.43	70.29

AUC, area under the curve; Qa, blood flow at brachial artery feeding AVF; Qmin, the minimal blood flow value of the 4 sites (brachial artery feeding the AVF, anastomosis, 5 cm and 10 cm from the anastomosis); VAPR, venous access pressure ratio; Sens, sensitivity; Spec, specificity; PPV, positive predictive value; NPV, negative predictive value.