Table 1.

Characteristics of trials and observational studies included in the review

Study	Year of publication	Number of patients	Site of treatment	Outcome	Study design
Van Zundert32	2003	18	Cervical radicular	72% of patients pain relief of 50% at 4 weeks	Observational
Van Zundert28	2007	23	Cervical radicular	At 3 months, the PRF group showed a significantly better outcome with regard to the global perceived effect (>50% improvement) and VAS (20 point pain reduction)	Trial PRF vs SHAM
Chao SC33	2008	49	Cervical radicular	55% of patients pain relief of 50% at 3 months	Observational
Choi GS35	2011	15	Cervical radicular	77.3% of patients pain relief of 50% at 3 months	Observational
Choi GS34	2012	21	Cervical radicular	66% of patients pain relief of 50% at 3 months; 71% of patients satisfied at 12 months	Observational
Yoon YM36	2014	22	Cervical radicular	68% success rate after 6 months	Observational
Wang F30	2016	62	Cervical radicular	At 1, 3 and 6 months of follow-up, the combined therapy achieved significantly lower NRS and higher GPE compared with CNRB or PRF alone group (p < 0.001)	Trial PRF + CNRB vs PRF alone vs CNRB
Halim W29	2016	34	Cervical radicular	Within 3 months, both PCN and PRF show significant pain improvement in patients with contained cervical disk herniation, but none is superior to the other	Trial vs PCN
Lee DG31	2016	38	Cervical radicular	No statistically significant difference was observed between the PRF and TFESI groups in terms of VAS scores at any time during follow-up	Trial PRF vs TFESI
Mikeladze40	2003	114	Spondylosis/facet pain	59% patients respond favourably (pain reduction more than 50%)	Observational
Lindner R41	2006	48	Spondylosis/facet pain	21/29 non-operated patients and 5/19 operated patients, the outcome was successful	Observational
Tekin I38	2007	20	Spondylosis/facet pain	PRF and CRF are effective but PRF is not as long lasting as CRF	Trial PRF vs CRF
Kroll HR39	2008	25	Spondylosis/facet pain	No significant difference between CRf and PRF, there was a greater improvement over time noted within the CRF group	Trial PRF vs CRF
Colini-Baldeschi42	2012	300	Spondylosis/facet pain	62% of patients reported good pain relief at 1 month	Observational
Teixeira A47	2006	8	Intradiscal	100% fall of the NRS score of at least 4 points at the 3-month follow-up	Observational
Rohof O49	2011	76	Intradiscal	38% of the patients had >50% pain reduction (3 months), 29% (12 months)	Observational
Fukui S48	2012	31	Intradiscal	The mean NRS was significantly improved from 7.2 ± 0.6 pre-treatment to 2.5 ± 0.9 in the disc PRF group, and from 7.5 ± 1.0 to 1.7 ± 1.5 in the IDET group (6 months)	Trial PRF vs IDET
Jung YJ50	2012	26	Intradiscal	Successful outcome in 58%, 50% and 42% patients, measured at 3, 6 and 12 months post-treatment	Observational
Fukui S51	2013	23	Intradiscal	65.2% had >50% pain reduction, 12 months after treatment	Observational
Teixeira A52	2005	13	DRG in disc herniation and radiculitis	NRS fell from 7.83 to 2.25 over the first 2 weeks, followed by a gradual further fall to 0.27 at the final follow-up, 15.8 (11–23) months after the procedure	Observational
Martin DC53	2007	8	DRG in disc herniation and radiculitis	Treatment were effective from 2 to 12 months	Observational
Abejón D54	2007	54	DRG in disc herniation and radiculitis	A decrease in the NRS score was observed in patients with HD and SS, but not in those with FBSS	Observational
Chao SC33	2008	116	DRG in disc herniation and radiculitis	44 % of patients had pain relief of 50% or more at the follow-up period of 3 months	Observational
Simopoulos TT55	2008	76	DRG in disc herniation and radiculitis	70% of the patients treated with PRF and 82% treated with PRF + CRF had a successful reduction in pain intensity at 2 months	Trial vs PRF + CRF
Tsou HK57	2010	127	DRG in disc herniation and radiculitis	55.10% of patients had initial improvement ≥50% at 3-month follow-up	Observational
Van Boxem K56	2011	60	DRG in disc herniation and radiculitis	The primary end point was achieved in 29.5% of all the PRF interventions. After 6 months, 50% pain relief was still present in 22.9% of the cases and after 12 months in 13.1% of the cases	Observational
Nagda JV58	2011	50	DRG in disc herniation and radiculitis	100% of patients were identified who received 50% pain relief or better after PRF and CRF	Observational PRF + CRF
Shanthanna H59	2014	31	DRG in disc herniation and radiculitis	6 of 16 patients in the PRF group and 3 of 15 in the placebo group showed a >50% decrease in VAS score	Trial vs SHAM
Koh W61	2014	62	DRG in disc herniation and radiculitis	The number of patients with successful treatment results was higher in the PRF group at 2 months and 3 months	Trial vs corticosteroid injection
Van Boxem K60	2015	65	DRG in disc herniation and radiculitis	Clinical success was achieved in 56.9%, 52.3% and 55.4% of the patients at 6 weeks, 3 months and 6 months, respectively	Observational
Vallejo R67	2006	126	SIJ	72.7% of patients experienced “Good” (>50% reduction in VAS) or “Excellent” (>80% reduction in VAS) pain relief	Observational
Sluijter ME68	2008	1	SIJ	Successfully treated	Case report
Hashemi M71	2014	8	Spondylolisthesis	PRF significantly reduced NRS at 6-month follow-up compared with steroid + bupivacaine	Trial PRF vs steroid + bupivacaine
Ke M73	2013	96	Post-herpetic neuralgia	Short-term pain relief, and improved quality of life	Trial PRF vs SHAM

CNRB, cervical nerve root block; CRF, continuous radiofrequency; DRG, dursal root ganglia; FBSS, failed back surgery syndrome; HD, herniated disc; IDET, intradiscal electrothermal therapy; LBP, low back pain; NRS, numeric rating scale; PCN, percutaneous nucleoplasty; PRF, pulsed radiofrequency; SIJ, sacroiliac joint; SS, spinal stenosis; TFESI, transforaminal epidural steroid injections; VAS, visual analogue scale.