Table 1.

Quality assessment of studies included in the systematic review

Study	Study type (P, R, PR)	Study type (RCT/obs)	Standardisation of imaging	Variability of diameter given	Patient selection criteria
Li, J., 2008	R	Obs	Y	N	All patients diagnosed as AAA during 1975 and 2007 in the Department of Geriatric Medicine of Beijing Hospital with imaging proof (US, CT or MRI)
Fan, L.H. 1999	Unclear	Obs	N	N	Not described
Wu, Q., 2009	R	Obs	N	N	All patients aged above 80 and diagnosed as AAA during January, 1997 and Juanuary, 2008 in People’s Liberation Army General Hospital
Zhang, L.F., 2006	P	Obs	Y	N	All patients whose medical history and imaging data are complete and aneurysm had been regularly monitored after being diagnosed as AAA in Air Force General Hospital.
Zhao, B. 2008	P	Obs	N	N	Randomly selected from outpatients and inpatients diagnosed with AAA during US screening, and with no syptom or sign.
Song, H.G., 2013	R	Obs	N	N	Not described.

Abbreviations: N no, U unclear, Y yes, Obs observational study, P prospective, PR prospective and retrospective, R retrospective, RCT randomized controlled trial