Study reference

Study characteristics

Patient characteristics

Intervention (I)

Comparison/ control (C)

Follow-up

Outcome measures and effect size

Comments

Li, 2016

PS., study characteristics and results are extracted from the SR (unless stated otherwise)

SR and meta-analysis of (cohort studies)

Literature search up to May, 2015

A: Ahmed, 2015

B: Maleo-Milewska, 2014

C: Johnston, 2012

D: Sagir, 2011

E: Demircay, 2010

F: Agarwal-Kozlowski, 2009

G: Reig, 2005

H: Park, 2015

I: Gunduz, 2015

J: Mastroluca, 2011

K: Abejon, 2007

L: Plancarte-Sanchez, 2005

M: Hamaguchi, 2003

N: Swofford, 1998

O: Anwer, 2011

P: Ozyalcin, 1996

Study design: All were cohort studies, type of cohort study not reported (prospective / retrospective).

Setting and Country: not reported per study.

Source of funding and conflicts of interest:

Not reported per study.

Li (2016) declares the authors have no conflict of interest. Funding not reported.

Inclusion criteria SR: (1) GIB as an intervention for chronic intractable pelvic and/or perineal pain; (2) Including the effective rate or the VAS score comparison between baseline and post-treatment.

Exclusion criteria SR: (1) Patients with severe cardiovascular and cerebrovascular diseases or other contradictions of the block; (2) Duplications; (3) Missing data; (4) The simple qualitative description; (5) Incorrect statistical analysis performed in the report.

16 studies included

Important patient characteristics at baseline:

Number of patients; characteristics important to the research question and/or for statistical adjustment (confounding in cohort studies); for example, age, sex, bmi,...

N, mean age

A: 15 patients, 54.3 (SD 13.3) yrs

B: 9 patients, 43-73 years

C: 1 patients, 67 years

D: 1 patient, age unknown

E: 10 patients, 42.9 (SD 14.4) years

F: 43 patients, 64.4 (SD 12.4) years

G: 13 patients, 35-76 years

H: 4 patients, age not reported

I: 22 patients, 41 (SD 9) years

J: 11 patients, age not reported

K: 35 patients, 53 (SD 17) years

L: 16 patients, 24-87 years

M: 1 patient, 62 years

N: 20 patients, 35-70 years

O: 14 patients, age not reported

P: 30 patients, 36-68 years.

Sex: not reported per study.

Pain:

A: chronic pelvic pain and chronic perineal pain

B: chronic pelvic pain

C: chronic perineal pain

D: Chronic coccydynia

E: Chronic coccydynia

F: chronic perineal pain

G: chronic perineal pain

H: chronic perineal pain

I: Chronic coccydynia

J: chronic perineal pain

K: chronic perineal pain

L: chronic perineal pain

M: chronic perineal pain

N: chronic perineal pain

O: chronic pelvic pain and chronic perineal pain

P: chronic perineal pain

Groups comparable at baseline?

Describe intervention:

Post-intervention outcome

Block:

A: GIB + SHGPB

B: GIB

C: GIB

D: GIB

E: GIB +RFT

F: GIB + N

G: GIB + RFT

H: GIB

I: GIB

J: GIB +PR

K: GIB + RFT

L: GIB

M: GIB + CB

N: GIB

O: GIB+N

P: GIB

Block drugs

A: 4-6 mL 8% phenol + 1 mL saline + 10 mL 10% phenol + 1 mL saline

B: 4-6 mL (65% alcohol + lidocaine)

C: 10 mL 0.25% chirocaine + 75 ug clonidine

D: 9 mL 0.25% chirocaine + 1 mL-40 mg methylprednisolone

E: 10 mL 0.25% chirocaine

F: 10 mL 1.0% ropivacaine + 2 mL 95% alcohol

G: 5 mL 0.2% ropivacaine + 40 mg triamcinolone

H: 4 mL 0.5% lidocaine + 5 mL 0.2% ropivacaine + 20 mg triamcinolone

I: 2 mL 0.5% bupivacaine + 2 mL saline + 40 mg methylprednisolone

J: not reported

K: not reported

L: 4 mL (1% lidocaine or 0.25% bupivacaine) + 4-6 mL 10% phenol

M: 5 mL 0.25% bupivacaine + 4 mL 7% phenol

N: 5 mL 0.25% bupivacaine + 20 mg triamcinolone

O: Bupivacaine + absolute alcohol

P: 6 mL 0.25% bupivacaine + 6 mL 6% phenol

Describe control:

Baseline score

End-point of follow-up:

A: 2 months

B: 3 years

C: 5 days

D: not reported

E: 9.1 (SD 1.2) months

F: 4 months

G: 6 months

H: 3 months – 2 years

I: 6 months

J: 6 months

K: 1 year

L: 14-120 days

M: 6 months

N: not reported

O: 1 month

P: 6 months

For how many participants were no complete outcome data available?

Not reported per study.

Outcome measure-1: pain

Defined by VAS score 0-10, no to maximum pain.

Pain score was calculated in 2 manners:

1. OR (95% CI) of the VAS score lowering <50%

Pooled effect (fixed effects model): 0.01 (95%CI 0.00, 0.02) favoring post-treatment score (people treated with GIB have an extremely low odds to experience less than 50% improvement in pain.

Heterogeneity (I²): 0%

2. mean difference between pre- and post-procedure VAS score:

Pooled mean difference -5.98 (95%CI -7.14 to -4.81) favoring post-procedure.

N=110 patients, n=4 studies included (K, F, E. I)

3. mean difference between pre- and 1 month post-procedure:

Pooled mean difference -5.56 (95%CI -6.93 tot -4.18) favoring 1 month post-procedure.

N=69, n=4 studies included (K,A,E,B)

Outcome measure-2: patient satisfaction

Not reported

Outcome measure-3: complications

Number of complications as reported per study.

All the included studies described the complications of GIB. Of all the 245 participants, however, there were only five patients with transient paresthesia and three patients with injection pain (study A).

Outcome measure-4: quality of life

Not reported.

Facultative:

Brief description of author’s conclusion

“In conclusion, this meta-analysis demonstrated that GIB can effectively alleviate the chronic intractable pain with few complications. And our results provided the true and reliable evidence for the clinical application of GIB in chronic intractable pelvic and/or perineal pain. Accordingly, the clinicians should further understand this method and keep improving it. Nevertheless, we don’t primarily recommend GIB for the general pain because of the probable damage of nerve. Further investigations should be operated to explore and improve the application of GIB.”

Personal remarks on study quality, conclusions, and other issues (potentially) relevant to the research question

Level of evidence: GRADE (per comparison and outcome measure) including reasons for down/upgrading

Sensitivity analyses (excluding small studies; excluding studies with short follow-up; excluding low quality studies; relevant subgroup-analyses); mention only analyses which are of potential importance to the research question

Heterogeneity: clinical and statistical heterogeneity; explained versus unexplained (subgroupanalysis)

Study

First author, year

Appropriate and clearly focused question?¹

Yes/no/unclear

Comprehensive and systematic literature search?²

Yes/no/unclear

Description of included and excluded studies?³

Yes/no/unclear

Description of relevant characteristics of included studies?⁴

Yes/no/unclear

Appropriate adjustment for potential confounders in observational studies?⁵

Yes/no/unclear/notapplicable

Assessment of scientific quality of included studies?⁶

Yes/no/unclear

Enough similarities between studies to make combining them reasonable?⁷

Yes/no/unclear

Potential risk of publication bias taken into account?⁸

Yes/no/unclear

Potential conflicts of interest reported?⁹

Yes/no/unclear

Li, 2016

Yes

Yes

Yes

Yes, except it was not reported whether outcome data were all complete and how many men and women were included.

Unclear, not performed (comparison of pre- and post-baseline scores)

Yes

Yes

Yes

No

Study reference

Study characteristics

Patient characteristics ²

Intervention (I)

Comparison / control (C) ³

Follow-up

Outcome measures and effect size ⁴

Comments

Fang, 2018

Type of study: prospective,

randomized controlled clinical trial

Setting and country: single centre, unclear if this was secondary or tertiary care facility, China.

Funding and conflicts of interest: source of funding not reported; The authors report no conflicts of interest in this work.

Inclusion criteria: 1)

pain located in the pudendal nerve distribution area; 2) pain intensity increases in the sitting position; 3) no nocturnal pain

symptoms; 4) pain with no objective sensory impairment

and 5) pain is relieved by diagnostic pudendal NB. Another clinical standard provides extra support to the diagnosis of pudendal neuralgia: 6) the pain symptom is associated with

sexual dysfunction, with the elimination of obstetrical and

gynecologic, urological and anorectal diseases in the related

departments and absence of any physical and mental disorders; 7) treatment by other departments is invalid; 8) patients

should be older than 18 years and 9) patients should be able to sign an informed consent form.

Exclusion criteria: 1) patients have simple tailbone, gluteus muscle

or lower abdominal pain, or only paroxysmal pain, or only pruritic symptoms, and/or have imaging anomalies that may

explain the symptoms; 2) female patients who are pregnant;

3) patients who take anticoagulant drugs or have any coagulation disorder; 4) patients who are unable to complete the questionnaire; 5) patients with pain, which is caused by

malignant or autoimmune diseases and 6) patients who are

hypersensitive to metals.

N total at baseline:

Intervention: 40 (1 patient was lost to follow-up, n for analysis = 39)

Control: 40 (2 patients were lost to follow-up; n for analysis = 38)

Important prognostic factors²:

For example

age ± SD:

I: 45±15.1

C: 45.1±12.6 years

Sex: UNCLEAR, not reported in text. Both appeared to have been included.

I: % M

C: % M

Symptom duration:

I: 7.4±3.9 months

C: 6.4±3.8 months

Groups comparable at baseline? Yes, except for BMI (NB group had higher BMI than PRF group) (25.4±3.9 versus. 23.3±3)

Describe intervention (treatment/procedure/test):

Nerve block:

After pulling out the needle core, the surgeon injected 5

mL of the nutrient nerve compound (compound liquid 20

mL=Neurotropin® 6 mL+2% lidocaine 5 mL+0.75% ropivacaine 2 mL+0.9% NaCl 7 mL). Then, the surgeon removed

the puncture needle and compressed this area for 3 minutes

for hemostasis. The puncture point should be covered with

sterile material for 3 days to prevent any infection.

Describe control (treatment/procedure/test):

Nerve block + pulse radiofrequency

After connecting the electrode and the PRF needle, the surgeon determined whether the pudendal nerve innervation

produced paresthesia in the sensory stimulation test with a frequency of 50 Hz, pulse width of 1 ms and a voltage of 0.3–0.5 V. Thereafter, the radiofrequency ablation therapy was performed in 42°C, 120 seconds pulse mode (PMG230 Baylis Medical Company Inc., Montreal, QC, Canada), which consisted of two cycles. Following that, the surgeon injected 5 mL of the nerve nutrition compound liquid through radiofrequency trocar after pulling out the radiofrequency electrode.

Finally, the surgeon removed the puncture needle. The other care treatment was the same as in the former group.

We defined 24–48 hours after surgery as the first postoperative day (POD). All patients returned to the ward after the

operation and received the minimum oral dose of pregabalin (one tablet twice daily after meals) as a routine pain treatment

from POD, in order to obtain relief from pain and to control the visual analogue scale (VAS) score below four points. When patients had a breakthrough pain, they were recommended to

relieve the pain by taking one oxycodone–acetaminophen tablet.

Length of follow-up: 3 months

Loss-to-follow-up:

Intervention: 1

N (%) 1/40

Reasons (describe) “lost to follow-up”, reason not reported.

Control: 2

N (%) 2/40

Reasons (describe) “lost to follow-up”, reason not reported n=1; ‘refused to participate in next visits’ n=1.

Incomplete outcome data: not reported.

Intervention:

N (%)

Reasons (describe)

Control:

N (%)

Reasons (describe)

Outcome measures and effect size (include 95%CI and p-value if available):

Outcome measure-1: Pain score

Defined as pain as reported on VAS score (0-10, least to worst pain (assumed)).

Baseline score:

I: 5.5 (SD 1.4)

C: 5.7 (SD 1,3)

P=0.631

Difference between groups in post-intervention scores:

1 month

I: 5.1 (SD 1.8)

C: 3.3 (SD 1.9)

P=0.001

3 months

I: 5.2 (SD 1.9)

C: 3.9 (SD 2.1)

Outcome measure-2: patient satisfaction

Not reported.

Outcome measure-3: complications

Descriptive presentation of reported complications. Participants were enquired at each

follow-up visit if they had any adverse reactions and

accident medical events during the period from the last

visit, including hypertension or hypotension, dizziness,

nausea, vomiting, lower limb numbness, urinary retention, puncture point of hematoma and so on. The doctors

recorded every adverse event and reported them on time.

Adverse reactions at 3 months follow-up.

Hypertension

I: 1/39

C: 1/38

P=0.985

Dizziness

I: 2/39

C: 1/38

P=0.547

Outcome measure-4: quality of life

Not reported.

Complete description of procedure:

The patients were treated as follows. The patient was made to lie in a prone position and a thin pillow was placed under the patient’s anterior lower abdomen and the projection area of the pudendal nerve on the body surface was labeled. Thereafter, the skin was sterilized by povidone iodine and a sterile surgical towel was placed on the patient (Figure 1A). The areas were scanned and marked by low-resolution (12–16 mHz) linear array transducer probe (S-Nerve; Sonosite, Bothell, WA, USA). First, in order to identify the bone sign of the ischial spine, an ultrasound transducer was placed at the level of the sacrospinous ligament and the internal iliac artery and the pudendal nerve position were identified (Figure 1B). Then, local anesthesia was administered by skin infiltration of 1% lidocaine. Second, under the guidance of ultrasound (S-Nerve, Sonosite), the 20 G, 10 cm puncture needle with 5 mm tip (RF Simject Cannula; NeuroTherm, Wilmington, MA, USA) was inserted near the pudendal nerve (Figure 1C). On entering into the visual operating area, the surgeon should pay attention to the patient’s response (the patient’s painful response appears in the same position, but is more severe than usual). Later, the surgeon proceeded with the treatment according to the protocol of the two groups.

Hetta, 2018

Type of study: A Double-Blind, Sham-Controlled, Randomized Trial

Setting and country: single centra, university hospital, Egypt.

Funding and conflicts of interest: There was no external funding in the preparation of this manuscript. Conflict of interest. The authors declare no conflict of interest.

Inclusion criteria: patients with chronic scrotal pain (orchialgia) that fulfilled the following criteria: 1) pain intensity ≥ 5 on the visual analog scale (VAS), 2) pain that lasted for more than 3 months after groin surgeries, 3) failed conservative treatment with nonsteroidal anti-inflammatory drugs (NSAIDs), and 4) showed more than 50% reduction of their orchialgia on the VAS for at least 6 hours following spermatic cord block with 6 mL of lidocaine 2%.

Exclusion criteria: 1) patients with other causes of scrotal pain, e.g., epididymitis, orchitis, and hydrocele, 2) patients complaining of groin infection and coagulopathy, 3) patients suffering from hypertension, ischemic heart disease, or psychiatric disorders, and 4) patients allergic to study medications and concomitant use of NSAIDS or monoamine oxidase inhibitors

N total at baseline:

Intervention: 35

Control: 35

Important prognostic factors²:

For example

age ± SD: n=30

I: 35.8 (SD 9.7)

C: 3.7 (SD 10.4)

Sex: 100%M

Groups comparable at baseline? Yes

Describe intervention (treatment/procedure/test):

Pulsed radiofrequency to the ilioinguinal nerve and genital branch of the genitofemoral nerve

We sterilized the lower abdomen from the umbilicus to the scrotum, then, we started the ultrasound (US) scanning using an M-Turbo machine (SonoSite, Inc., Bothell, WA) with a superficial linear probe 10 HZ frequency. The scanning process was implemented from the anterior superior iliac spine towards the umbilicus, keeping the shadow of iliac bone in view. The ilioinguinal nerve was identified in the fascial splitting area between the fascia transversalis and internal oblique muscles, just medial to the shadow of iliac bone (Fig. 1). A 22-gauge, 10 cm RF needle with a 10 mm active tip was introduced out of plane towards the nerve, and localization was further confirmed by producing a groin pain at 50 HZ and less than 0.5 volt sensory stimulation and contraction of the lower outer quadrant of the abdominal muscles at 2 HZ and less than 1 volt motor stimulation. After satisfactory needle position was confirmed, PRF was initiated using the following parameters: voltage output:

40–60 V; 2 Hz frequency; 20 ms pulses in a one-second cycle, 120 second duration per cycle and 42°C plateau temperature. PRF was applied for 4 cycles. The genital branch of the genitofemoral nerve was targeted under US guidance with the same probe, where the assistant held the testis and the cord and the probe was applied transversely just distal to the external inguinal ring; the deferent duct is visible as a non-compressible, internal hypoechoic structure with a hyperechoic horizon (Fig. 2). A 22-gauge, 10 cm RF needle with a 10 mm active tip was advanced out of plane just lateral to the deferent duct and manipulated to achieve scrotal pain at 50 HZ and less than 0.5 volt sensory stimulation. After localization of the nerve, PRF was commenced with the same parameters applied for the ilioinguinal nerve.

Describe control (treatment/procedure/test):

Sham procedure

The sham group (n = 35) was the control group, and the same procedure applied for the interventional group was done without giving PRF. The procedure was done by a senior staff pain clinician.

Length of follow-up: until 3 months post-intervention.

Loss-to-follow-up:

Intervention:

N (%) 5 (14.3%)

Reasons (describe) n=3 (8.6%) lost to follow-up, not further defined; n=2 (5.7%) excluded due to protocol violation, not further explained.

Control:

N (%)5 (14.3%)

Reasons (describe) n=2 (5.7%) lost to follow-up, not further defined; n=3 (8.6%) excluded due to protocol violation, not further explained.

Incomplete outcome data:

Intervention: 0

N (%)

Reasons (describe)

Control: 0

N (%)

Reasons (describe)

Outcome measures and effect size (include 95%CI and p-value if available):

Outcome measure-1: Pain score

Defined as >50% reduction of VAS pain score at 3 months post-operation.

I: 24/30 (80%)

C: 7/30 (23.33%)

Defined as mean VAS score (scale 0-10, presumably)

I: 2.40 (95%CI 1.92 – 2.89)

C: 3.17 (2.79 – 3.56)

P=0.001

Outcome measure-2: patient satisfaction

Not reported.

Outcome measure-3: complications

Not reported.

Outcome measure-4: quality of life

Not reported.

Kircelli, 2019

Type of study: retrospective observational study.

Setting and country: single centre, university hospital, Turkey.

Funding and conflicts of interest: funding not reported. The authors state that they don’t have any conflict of interest.

Inclusion criteria: Patients with traumatic or nontraumatic coccydynia with no response to conservative therapy, such as NSAIDs, those with pain despite the use of sitting pillows, and those with chronic (more than 6 months) coccydynia even after physical therapy or local injections were included in our study.

Exclusion criteria: pilonidal sinus/cysts, lumbar disc herniation, rectal problems, and gynecologic or pelvic diseases; pregnant or lactating patients; and those with a sensitivity to local anesthetics

N total at baseline:

Intervention: 20 (follow-up)

Control: 20 (baseline)

Important prognostic factors²:

For example

age ± SD: 48.7 (SD 14.3)

Sex: 55% M; 45% F

Mean duration of symptoms: >6 months, mean not reported.

Aetiology CC: 40% trauma, 60% idiopathic.

Groups comparable at baseline? Not applicable.

Describe intervention (treatment/procedure/test):

Post-intervention score:

Radiofrequency thermocoagulation (RFT) was performed on patients who underwent a diagnostic ganglion impar blockade and achieved at least 80% temporary pain relief. The RFT procedure was similar to ganglion impar blockade with the modified technique of Reig et al.9 After inserting and confirming the position of a 22-gauge, 5-mm active-tip radiofrequency needle under imaging guidance in anteroposterior and lateral fluoroscopic views, electrical sensory stimulation was applied at 50-Hz cycles/s; 1 mL of 2% lidocaine was used before RFT to minimize pain. For successful electrical sensory stimulation, the location of the response should be consistent with the distribution of the patient’s usual pain. During the procedure, the patients were asked whether they felt any pain.10,11 Once the denervation process began, the patient confirmed whether the pain felt similar to the previous pain. The patients were assured that they could end the procedure at any time if they did not feel well enough to continue. RFT was performed at 80°C for 120 seconds (Figure 3). The patients did not receive any additional medication after the procedure.

Describe control (treatment/procedure/test):

Baseline score (before intervention with impar block + RFT.

Length of follow-up: 12 months (mean 17.3 (SD 2.9) months)

Loss-to-follow-up: not reported

Intervention:

N (%)

Reasons (describe)

Control:

N (%)

Reasons (describe)

Incomplete outcome data: not reported

Intervention:

N (%)

Reasons (describe)

Control:

N (%)

Reasons (describe)

Outcome measures and effect size (include 95%CI and p-value if available):

Outcome measure-1: Pain score

Defined as pain as reported on VNS score (0-10, least to worst pain).

Difference between pre- and post-baseline score:

I (1 month post-baseline): 2.0 (SD 0.9)

C (baseline score): 9.0 (SD 0.8)

I (6 months post-baseline): 2.5 (SD 1.2)

C (baseline score): 9.0 (SD 0.8)

I (12 months post-baseline): 2.0 (SD 2.1)

C (baseline score): 9.0 (SD 0.8)

Outcome measure-2: patient satisfaction

Not reported.

Outcome measure-3: complications

Descriptive information on complications was reported.

“No complications related to the procedure, such as infection, neurological deficit, or bleeding, were observed.”

Outcome measure-4: quality of life

Not reported.

Complete description of procedure:

The procedure was performed in the operating room after routine surgical preparation under local anesthesia and light sedation. Sterile preparation was accomplished using a povidone iodine antiseptic solution with the patient in the prone position on a fluoroscopy table and C-arm fluoroscopic guidance. After local anesthetic injection, a 9-cm-long, 21gauge spinal needle (Arrow StimuQuik insulated peripheral nerve block needle, Teleflex, Morrisville, NC, U.S.A.) was introduced through the sacrococcygeal junction or from the first intercoccygeal junction anteriorly, and then the needle was tapped until it was 1 to 2 mm beyond the anterior aspect of the sacrococcygeal junction. The position of the tip of the needle was visualized by fluoroscopic guidance with contrastenhanced imaging using 1 mL of nonionic, radiocontrast dye injected retroperitoneally. The “reverse comma” aspect of the contrast dye under lateral fluoroscopy is shown in Figure 2. If the reverse comma sign was not observed due to sacrococcygeal ligament fusion, then the C1–C2 intercoccygeal junction was used. Ganglion impar blockade was performed with 10 mL of 0.25% bupivacaine in all patients, and 80% pain relief was observed for 2 to 6 hours.

Usmani, 2018

Type of study: prospective, randomized, double-blind study.

Setting and country: Two different interventional pain management centers in India.

Funding and conflicts of interest: not reported.

Inclusion criteria: age 15 and 75years with chronic nononcological perineal pain of at least six weeks’ duration who were unresponsive to conservative treatment (gabapentin oral 300mg three times a day). Diagnostic ganglion Impar block with 1.5mL of 0.25% bupivacaine was performed, and the patients showing at least 50% pain relief lasting for two to six hours were selected.

Exclusion criteria: Patients with coexisting coagulation abnormalities or prolonged bleeding time or septicemia, as demonstrated by elevated white blood cells or infection overlying the entry area, were excluded from the study. Patients receiving anticoagulant, aspirin or nonsteroidal antiinflammatory drug, or showing hypersensitivity to local anesthetic agents were also excluded.

N total at baseline:

Intervention: 35 (n for analysis = 34).

Control: 35 (n for analysis = 31).

Important prognostic factors²:

For example

age ± SD:

I: 39.32 (SD 14.29)

C: 42.32 (SD 15.64)

Sex: UNCLEAR

I: % M

C: % M

Symptom duration:

I: 13.7 (SD 9.3) months

C: 15.2 (SD 8.3) months

Diagnosis:

Coccygodynia

I: 29 (85.4%)

C: 25 (80.6%)

Chronic anal pain:

I: 1 (3%)

C: 3 (10%)

Chronic perineal pain:

I: 1 (3%)

C: 3 (10%)

Sacrococcygeal pain:

I: 3 (9%)

C: 0

Groups comparable at baseline? Yes

Describe intervention (treatment/procedure/test):

Conventional radiofrequency thermocoagulation

Patients in the CRF group (N=35) underwent radiofrequency lesioning at 80 degrees Celsius for 90seconds. As CRF application is a painful procedure and to avoid confounding effect, 1mL of 2% lidocaine was injected through the RF needle before performing conventional or pulsed radiofrequency ablation.

The patients were allowed to take a single tablet of tramadol and paracetamol (37.5mg + 325mg) combination, when required, during the study period, with a minimum interval of six hours between each dose. Gabapentin (300mg three times a day) was continued in the same dose as in the pretreatment period.

Describe control (treatment/procedure/test):

Pulsed radiofrequency neuromodulation

Patients in the PRF group (N=35) received treatment consisting of passage of pulsed RF current at 42 degrees Celsius for four minutes, two cycles of 120 seconds each.

As CRF application is a painful procedure and to avoid confounding effect, 1mL of 2% lidocaine was injected through the RF needle before performing conventional or pulsed radiofrequency ablation.

The patients were allowed to take a single tablet of tramadol and paracetamol (37.5mg + 325mg) combination, when required, during the study period, with a minimum interval of six hours between each dose. Gabapentin (300mg three times a day) was continued in the same dose as in the pretreatment period.

Length of follow-up: 6weeks

Loss-to-follow-up:

Intervention:

N (%) 1/35

Reasons (describe) not reported

Control:

N (%) 4/35

Reasons (describe) not reported

Incomplete outcome data: not reported

Intervention:

N (%)

Reasons (describe)

Control:

N (%)

Reasons (describe)

Outcome measures and effect size (include 95%CI and p-value if available):

Outcome measure-1: Pain score

Defined as pain as reported on VAS score (0-10, least to worst pain (assumed)).

Baseline score:

I: 7.76 (SD 1.25)

C: 7.88 (SD 1.07)

P=0.4665

Difference between groups in post-intervention scores:

6 weeks post-baseline

I: 1.96 (SD 1.4)

C: 6.12 (SD 2.02)

P=0.0001

Outcome measure-2: patient satisfaction

The patient’s satisfaction was graded as excellent when he/she reported significant pain relief and improvement in sitting and standing. It was graded as good when the patient reported lower pain than baseline but required intermittent analgesics. The satisfaction was graded as poor when the patient continued using analgesics in the same dose as before the block or there was only mild or no improvement

6 weeks post-baseline:

excellent/good satisfaction

I: n=28 (82.3%)

C: n=4 (12.9%)

Poor satisfaction:

I: n=6 (17.6%)

C: n=27 (87.1%)

P for overall test = 0.002

Outcome measure-3: complications

Descriptive presentation of reported complications.

“Patients were discharged from the hospital after four hours of observation without any adverse sequelae. No untoward side effect or neurological complication other than infection at the site of skin puncture was observed during the follow-up period in any patient of the two groups. Infection at the site of skin puncture was found in three out of 34 patients in the CRF group and two out of 31 patients in the PRF group, which resolved after oral antibiotic treatment. The incidence of this complication was comparable in both the study groups.”

Outcome measure-4: quality of life

Not reported.

Complete description of intervention:

The procedure was performed with the patient in prone position on an x-ray translucent table. C-arm (Multimobil 5C, Siemens Ltd., India) was used to identify and mark the essential bony landmarks. No sedation was given. Under strict aseptic precautions, the sacrococcygeal and gluteal regions were cleaned with savlon and spirit and painted with povidone iodine 10%. The area was draped with sterile towels, and the access region was left open. In order to view the first intra-coccygeal joint, the C-arm was taken to the lateral position. After infiltrating the skin and subcutaneous tissues with 2% lidocaine, a 10-cm-long 22G radiofrequency cannula with 5-mm active tip (Cosman Medical Co Inc., MA, USA) was passed, until the tip reached anterior to the ventral intra-coccygeal ligament, felt as a tug or pull. The position of the needle tip was confirmed by injecting 1mL of radio-opaque dye in the presacral space. The spread of the dye gives a reverse comma appearance in the lateral view. A radiofrequency thermocouple electrode (Cosman Medical Co Inc., MA, USA) was passed through the radiofrequency cannula. The radiofrequency thermocouple electrode was connected to a Cosman radiofrequency generator (RFG-1A). Before radiofrequency ablation was performed, tissue impedance check and motor and sensory tests were done. These comprised tissue impedance<600Ohm, sensory response <50Hz, and a motor response <2Hz at a stimulation intensity between 0.4–0.8 volts (V).

Study reference

(first author, publication year)

Describe method of randomisation¹

Bias due to inadequate concealment of allocation?²

(unlikely/likely/unclear)

Bias due to inadequate blinding of participants to treatment allocation?³

(unlikely/likely/unclear)

Bias due to inadequate blinding of care providers to treatment allocation?³

(unlikely/likely/unclear)

Bias due to inadequate blinding of outcome assessors to treatment allocation?³

(unlikely/likely/unclear)

Bias due to selective outcome reporting on basis of the results?⁴

(unlikely/likely/unclear)

Bias due to loss to follow-up?⁵

(unlikely/likely/unclear)

Bias due to violation of

intention to treat analysis?⁶

(unlikely/likely/unclear)

Fang, 2018

A random assignment sequence was generated by the computer

Unlikely

Unlikely

Unclear, it was not possible to blind care providers to the treatment allocation. All treatments were performed by the same surgeon, follow-up and evaluation were done by others.

Unclear, not reported

Unlikely

Unclear, follow-up was almost equal (1 versus. 2) in both groups; reasons not reported.

Unlikely

Hetta, 2018

The patients were randomly allocated to 2 groups by using a computer-created number list, which was concealed in sealed envelopes without blocking, and they were open by the researcher before application of the procedure.

Unlikely

Unlikely

Unlikely

Unclear, it was reported that allocation was revealed to the researcher before application of the procedure. Unclear whether this researcher was the analyst also.

Unlikely

Unclear, follow-up was almost equal (2 versus. 3) in both groups; reasons not reported.

Likely, in the intervention group 2 patients (5.7%) were excluded due to protocol violation, in the control group 3 patients (8.7%) were excluded due to protocol violation. Not explained what the violations were or why they decided not to execute an intention to treat analysis and/or per protocol analysis.

Usmani, 2018

Patients were randomly divided into two groups using a computer-generated randomization schedule

Unlikely

Unclear, it was a double-blind design so bias seems unlikely. However it is not clarified in text how this was established.

Unclear, it was a double-blind design so bias seems unlikely. However it is not clarified in text how this was established.

Unclear, not reported

Unlikely

Likely, follow-up was 4 times higher in the PRF (n=4) versus. CRF group (n=1). Reasons not reported.

Unlikely.

Study reference

(first author, year of publication)

Bias due to a non-representative or ill-defined sample of patients?¹

(unlikely/likely/unclear)

Bias due to insufficiently long, or incomplete follow-up, or differences in follow-up between treatment groups?²

(unlikely/likely/unclear)

Bias due to ill-defined or inadequately measured outcome ?³

(unlikely/likely/unclear)

Bias due to inadequate adjustment for all important prognostic factors?⁴

(unlikely/likely/unclear)

Kircelli 2019

Unclear, patients with both trauma (n=8) and idiopathic (n=12) chronic coccydynia included.

Unclear, follow-up duration was 17.3 +/- 2.9 months on average, which implies almost every patient will have had follow-up data until 12 months. Lost to follow-up was not reported.

Unlikely

Unlikely, within-person comparisons were made with no drop-out.