Table 1.

Demographic characteristics

Index	ERFA group	Control group	P value
Cases (n)	30	30
Gender (male/female)	16/14	17/13	0.795
Age (years)	65.73 ± 7.62	64.78 ± 6.62	0.607
Duration of back pain (months)	46.83 ± 11.43	46.71 ± 11.21	0.967
History of lumbar surgery (yes/no)	10/20	9/21	0.781
BMI (kg/m2)	21.52 ± 1.32	21.44 ± 1.33	0.816
L3-4, L4-5, L5-S1	6, 16, 8	5, 17, 8	0.941