Table 3.

Patient reported outcome measures.

Parameter	Number of studies	Number of patients	Number of levels	Average pre-op	Average post op value	standard error of difference	P value
ODI	22	1059	2248	50.18	28.03	1.457	<0.0006
VAS for Leg pain	15	673	1281	6.29	3.06	0.284	<0.0001
VAS for Back Pain	13	609	1157	7.43	3.24	0.295	<0.0001
VAS (not specified)	7	384	980	7.7	3.37	0.391	<0.0001