Table 1. The characteristics of the included studies.

Study	Year	Country	TP	FP	FN	TN	Detection Method	Cut-off (ng/ml)
Body(a)	1992	Belgium	79	6	18	94	RIA	11.7
Body(b)	1992	Belgium	86	11	11	89	RIA	9.2
Burghuber	1990	Austria	63	53	18	299	RIA	12.3
Dienemann	1994	Germany	42	26	13	163	ELISA	13.7
Dilmaghani-Marand	2013	Germany	50	0	0	90	ELISA	29.5
Ebert	1996	Germany	95	34	35	348	RIA	13.8
ESSCHER	1985	Sweden	74	4	29	368	RIA	25
Feng	2010	China	4	72	4	192	ECSIA	15.2
FRANJEBIC	2012	Croatia	201	10	127	195	ECSIA	NA
Gruber	2008	Germany	78	2	116	316	RIA	35
Han	1994	China	10	14	8	31	ELISA	20
HOLDENRIEDER	2010	Germany	44	2	9	38	ECSIA	NA
Jaques	1993	Japan	75	0	146	87	RIA	25
Keller	1998	Germany	52	50	8	302	ELISA	18
Lamy	2000	France	110	4	36	55	ELISA	17
Li	2003	China	18	5	12	55	ELISA	8
Molina	2008	Spain	78	32	18	385	ELISA	25
Molina	2009	Spain	114	50	61	577	ELISA	25
Muley	2003	Germany	138	71	50	744	ECSIA	21.6
Niklinski	1993	Poland	30	0	18	15	ELISA	15
NISMAN	2009	Japan	18	15	19	110	ELISA	22
Pan	2002	China	19	51	5	99	ELISA	13
Pinson	1997	Belgium	47	20	17	96	RIA	12.5
Poposka	2004	Macedonia	24	11	9	79	RIA	16.6
Scagliotti	1989	Italy	44	5	18	42	RIA	12
Shibayama	2001	Japan	49	3	65	103	ELISA	7.5
Stieber	1993	Germany	34	14	28	259	RIA	18
STIEBER(a)	1999	Japan	39	4	48	70	RIA	11.9
STIEBER(b)	1999	Japan	25	1	61	73	RIA	23.1
Takada	1996	Japan	73	6	28	108	ELISA	10.6
Yang	2000	China	18	5	12	55	ELISA	8
Yang(a)	2005	China	14	41	7	103	ECSIA	16.3
Yang(b)	2005	China	40	16	23	65	ECSIA	16.3
Zhang	2002	China	6	22	2	106	RIA	20
Zhou	1995	China	16	13	4	72	ELISA	20.8

ELISA: enzyme linked immunosorbent assay; ECSIA: electro-chemiluminescence; Immunoassay assay; RIA= radioimmunoassay assay; TP=true positive; FP: false positive; FN: false negative; TN=true negative.