Table 4

Analysis of effect size, heterogeneity, and ANOVA testing of difference by surgery indication.

	Indication for Surgery	Number of Studies Included in This Analysis	Effect Size	Lower Limit	Upper Limit	Higgins I ² Statistic of Heterogeneity	Variance	Standard Error	Number of Patients
Oswestry Disability Index	Discogenic pain	2	0.9112	0.8866	0.9359	0.0000	0.0002	0.0126	216
	HNP radiculopathy	22	0.9179	0.8888	0.9471	0.0000	0.0002	0.0149	3520
	Stenosis claudication	14	0.9531	0.9290	0.9772	0.0000	0.0002	0.0123	1638
	ANOVA Q test random effects with separate estimates of T ²				Sig = 0.094		Total patient samples		5374
VAS back	Stenosis claudication	5	0.8745	0.7792	0.9698	0.0000	0.0024	0.0486	388
	HNP radiculopathy	10	0.7086	0.5522	0.8650	0.0000	0.0064	0.0798	1108
	ANOVA Q test random effects with separate estimates of T ²				Sig = 0.074		Total patient samples		1496
VAS leg	Stenosis claudication	13	0.9113	0.8673	0.9553	0.0000	0.0005	0.0225	1024
	HNP radiculopathy	23	0.8942	0.8612	0.9273	0.0000	0.0003	0.0169	3667
	Discogenic pain	3	0.8828	0.8204	0.9452	0.0000	0.0010	0.0318	320
	ANOVA Q test random effects with separate estimates of T ²				Sig = 0.74		Total patient samples		5011

ANOVA, analysis of variance; HNP, herniated nucleus pulposus; Sig, significance level of 95% CI; VAS, visual analog scale.