Table 3. Meta-regression for the potential source of heterogeneity.

Study characteristic	P-value	RDOR	95% CI
Specimen type (plasma, serum or tissue)	0.0587	0.56	(0.31-1.02)
Control sources (healthy blood, normal tissue or adjacent non-tumor tissue)	0.9385	0.90	(0.05-15.68)
Sample size (GC<100 vs. GC≥100)	0.1047	2.27	(0.82-6.23)
Reference gene (GAPDH vs. β-actin)	0.5264	0.73	(0.25-2.13)
Cut-off value (value <100 vs. value ≥100)	0.1798	0.71	(0.42-1.2)
Study quality (QUADAS score≤10 or≥11)	0.1008	3.29	(0.76-14.14)

Abbreviations: CI: confidence interval; RDOR: relative diagnostic odds ratio; QUADAS: quality assessment for studies of diagnostic accuracy; GC: Gastric cancer; GAPDH: glyceraldehyde-phosphate dehydrogenase