Table 1.

Summary of included studies

Ref.	Patients	Assay method	Cut off	Test results				Quality score
				TP	FP	FN	TN	STARD	QUADAS
Ribera et al[12]	86	RIA	3 U/mL or 9 U/mL	16	0	0	70	11	9
Soliman et al[13]	50	ELISA	26 pg/mL	13	0	3	33	15	12
Sathar et al[14]	92	RIA	3.2 U/mL	25	1	2	54	13	10
Saleh et al[28]	41	ELISA	0.35 IU/mL	13	0	1	27	16	11
Sharma et al[29]	119	ELISA	112 pg/mL	30	3	1	85	18	13
Sathar et al[30]	52	ELISA	20 pg/mL	21	0	2	29	14	12

ELISA: Enzyme-linked immunosorbent assay; RIA: Radioimmunoassay; TP: True-positive; FP: False-positive; FN: False-negative; TN: True-negative; STARD: Standards for Reporting Diagnostic Accuracy, maximum score 25, guidelines that aim to improve the quality of reporting in diagnostic studies; QUADAS: Quality Assessment for Studies of Diagnostic Accuracy, appraisal by use of empirical evidence, maximum score 14, expert opinion and formal consensus to assess the quality of primary studies of diagnostic accuracy.