Table 2.

Randomized trials with abnormal surveillance results and comparing intervention versus observation.

Name	Total no. of patients	Intervention	Conservative	Surveillance methods used	Primary outcome	Result
Lumsden et al., 1997 [37]	64	32	32	Color flow duplex scan	Cumulative patency	Negative
Martin et al., 1999 [64]	21	8	13	Color flow duplex scan	Virgin graft patency	Positive
Dember et al., 2004 [63]	64	32	32	Static venous pressure/systolic blood pressure ratio	Access survival	Negative
Tessitore et al., 2004 [65]	79	43	36	Access flow	Access survival, thrombosis	Positive
Scaffaro et al., 2009 [66]	108	53	58	Duplex scan	Thrombosis	Negative