Meta-Analysis of Visual Evoked Potential and Parkinson’s Disease

Table 2

Metaregression analysis and subgroup analysis.

Subgroup factor	Assign criteria	Number of studies	WMD (95% CI)	-difference between groups
Sample size	≤20	10	4.20 (1.38, 7.02)	0.001
	>20	10	7.64 (2.21, 13.1)
Publication year	Before 2000	10	6.25 (1.91, 10.6)	0.12
	2000 or later	10	5.79 (0.49, 11.1)
Age (years)	<64	9	9.39 (3.04, 15.7)	0.08
	≥64	11	3.38 (1.18, 5.58)
Proportion of men	>50%	8	4.47 (2.03, 6.91)	0.03
	≤50%	4	8.44 (−3.98, 20.9)
Duration (months)	≤56.4	8	4.82 (−2.31, 12.0)	0.01
	>56.4	7	6.38 (1.08, 11.6)

Adjusted for all factors in this table.