Table 2.

Assessment of study heterogeneity by meta-regression

Comparison of Subgroups	Coefficient (standard error)	p-value
Surgical treatment vs. nonsurgical treatment	−2.7% (2.7)	0.36
≥50% follow-up rate vs. <50% follow-up rate	−2.8% (2.7)	0.34
>12 months vs. 6–12 months follow-up duration	−4.5% (2.6)	0.13
Retreatment vs. initial treatment #	−2.3% (2.1)	0.35
Above-median vs. below-median reported study quality (STROBE criteria)	1.5% (2.6)	0.57

^#Four studies with missing data

Negative (−) sign indicates that first subgroup has higher pain frequency