Table 2.

Results of clinical parameters and SMAD4 expression in patients with NSCLC.

Clinical parameters	No. of studies	Overall OR (95% CI)	Heterogeneity test (Q, I2, P)
Age	1, 3, 4, 5, 6	0.822 (0.515–1.312)	0.45, 0.0%, .978 (fixed)
Gender	1, 3, 4, 5, 6, 7	1.056 (0.675–1.653)	5.72, 12.6%, .811 (fixed)
Differentiation	1, 2, 3, 4, 5, 6, 8	2.784 (1.842–4.209)	10.22, 41.3%, .116 (fixed)
N	1, 2, 3, 4, 6, 8	0.469 (0.304–0.725)	13.96, 64.2%, .0016 (random)
TNM	1, 2, 3, 4, 5, 6, 7	0.228 (0.156–0.362)	9.43, 36.4%, .151 (fixed)

NSCLC = non-small cell lung cancer, SMAD4 = SMAD family member 4, TNM = tumor node metastasis.