Table 4.

Result of source of control subgroup analysis of eNOS (4b/4a) polymorphism and DR risk in T2DM patients.

Variables	N	References	Case/control	Genetic model	Fixed-effects model		Random-effects model		Heterogeneity
					OR (95%CI)	p Value	OR (95%CI)	p Value	PH	I2 (%)
Source of control				Allelic model
HB	10	[8,15,22–24,36,38–40,42]	1720/1999		1.066(0.945–1.201)	.297	1.086(0.824–1.431)	.558	0.000	77.9%
PB	9	[4,10,11,16,18,19,28,37,41]	2139/1989		0.901(0.806–1.006)	.064	0.905(0.778–1.053)	.197	0.200	27.4%
				Recessive model
HB	10	[8,15,22–24,36,38–40,42]	1720/1999		0.961(0.714–1.294)	.796	0.941(0.593–1.492)	.794	0.060	45.0%
PB	9	[4,10,11,16,18,19,28,37,41]	2139/1989		1.014(0.772–1.331)	.922	1.034(0.783–1.366)	.813	0.613	0.0%
				Dominant model
HB	10	[8,15,22–24,36,38–40,42]	1720/1999		1.084(0.940–1.249)	.267	1.131(0.825–1.549)	.445	0.000	76.3%
PB	9	[4,10,11,16,18,19,28,37,41]	2139/1989		0.858(0.749–0.983)	.027	0.859(0.711–1.039)	.118	0.136	35.2%
				Additive model
HB	10	[8,15,22–24,36,38–40,42]	1720/1999		0.925(0.797–1.073)	.301	0.863(0.639–1.164)	.334	0.000	70.8%
PB	9	[4,10,11,16,18,19,28,37,41]	2139/1989		1.168(1.016–1.341)	.029	1.162(0.985–1.371)	.075	0.298	16.2%
				Homozygote model
HB	10	[8,15,22–24,36,38–40,42]	1720/1999		1.097(0.812–1.482)	.547	1.120(0.677–1.854)	.659	0.027	52.1%
PB	9	[4,10,11,16,18,19,28,37,41]	2139/1989		0.879(0.663–1.164)	.367	0.860(0.644–1.148)	.307	0.464	0.0%
				Heterozygote model
HB	10	[8,15,22–24,36,38–40,42]	1720/1999		1.084(0.933–1.260)	.293	1.164(0.848–1.599)	.348	0.000	73.4%
PB	9	[4,10,11,16,18,19,28,37,41]	2139/1989		0.847(0.735–0.977)	.022	0.850(0.702–1.028)	.094	0.172	30.8%

Note: PB: population-based; HB: hospital-based; N: number of studies; OR: odd ratio; 95%CI: 95% confidence intervals.

Bold indicates the P value was less than 0.05 and a significant association was found between eNOS (4a/4b) and the risk of incident DR.