Type of control: Sham Outcomes measured: VAS, global perceived effect, Impairment evaluation (Waddell), Oswestry Disability Index, and the COOPWONCA quality of life questionnaire Patient characteristics: 15 participants (10 women and 5 men) with a mean age of 46.67.4 years, were randomly assigned to receive the intervention. 16 participants (10 women and 6 men) with a mean age of 41.47.5 years were randomly assigned to receive the sham procedure. There were no statistically significant differences in patient characteristics between the sham and intervention groups procedure with the same placement as the intervention, but no current applied Outcome ascertainment: Baseline, 2 months Type of analysis: Not reported Van Wijk et al (23), 2005; The Netherlands Patient selection: Patients were recruited from 4 pain clinics between May 1996 and January 1999 Inclusion criteria: Older than 117, chronic low back pain for >6 months, no radicular

Type of control: Sham Outcomes measured: VAS, daily activities, analgesic intake, global perceived effect, Short Form-36 Health Survey, Zung Self Rating Depression Scale and Multidimensional Pain Inventory Patient characteristics: 40 participants (30 women and 10 men) with a mean age of 46.911.5 years were randomly assigned to receive the intervention. 41 participants (28 women and 13 men) with a mean age of 48.112.6 years were randomly assigned to receive the sham procedure. There were no statistically significant differences in patient characteristics between the sham and intervention groups procedure with the same placement as the intervention, but no current applied Outcome ascertainment: Baseline, 3 months Type of analysis: Not reported Continued on next page Pain Res Manag Vol 19 No 5 September/October 2014 e149 leggett et al Table 2 COnTInueD Characteristics of randomized controlled trials reporting the efficacy of radiofrequency ablation (RFa)

Baseline, 1 month, 3 months, 6 months 51.913.6 years were randomly assigned to receive the intervention; 14 participants (8 women and 6 men) with a mean age of 51.813.1 years were randomly assigned to receive the sham procedure. There were no statistically significant differences in patient characteristics between the sham and intervention groups, with the exception of military duty status, and baseline Oswestry Disability Index Scores procedure with the same placement as the intervention, but no current applied Type of analysis: Not reported Patel et al (21), 2012; United States Patient selection: Patients were recruited by the authors, the authors colleagues and using advertisements between July 2008 and July 2010. Participants were randomly assigned in a 2:1 ratio Inclusion criteria: Axial pain below the L5 vertebrae lasting >6 months, 3-day average NRS score rating between 4 and 8, >18 years of age, no response to conservative treatment

Exclusion criteria: History of intervertebral disc disease or zygopophyseal joint pain, Becks Depression Inventory score >20, psychological barriers to recovery, spinal pathology, infection, cervical or thoracic pain >2/10 on NRS, acute illness, pregnancy, radicular pain, immunosuppression, allergy to medications used, smokers, high narcotics use Patient characteristics: 34 participants (23 women and 11 men) with a mean age of 5613 years, were randomly assigned to receive the intervention. 17 participants (14 women and 3 men) with a mean age of 6414 years, were randomly assigned to receive the sham procedure. There were no statistically significant differences in patient characteristics between the sham and intervention groups Type of intervention: Continuous cooled RFA, with a 17-gauge cannula and 4 mm tip length, for 150 s using a temperature of 60C