Hruby 2006.

Study characteristics
Methods	Type of study: double blind, placebo‐controlled, parallel RCT. Condition and number of participants randomised: participants undergoing flexible cystoscopy (N = 148). Groups: active TENS group (N = 48); placebo TENS group (N = 49); control group (N = 51).
Participants	Demographics: N = 148, 108 male/40 female.  Active TENS Group, 62.23 yrs; placebo TENS Group, 61.53 yrs; control group, 60.98 yrs (? mean). Setting: office‐based. Inclusion: flexible cystoscopy for surveillance of transitional cell carcinoma; voiding symptoms; hematuria, or stent removal. Exclusion: participants with a neobladder; cystoscopy with biopsy or with dilation of strictures; participants taking chronic analgesics or with pain syndromes; and participants who required post procedure catheterization. Withdrawals/dropouts: not detailed.
Interventions	Where applied: in hospital. Applied by: clinician. Waveform: symmetric rectangular biphasic. Frequency: 100 pulses/s. Pulse duration: 180 μs. Pulse amplitude/Intensity: at the initial settings, the participant typically felt a slight tickle at the site of the electrodes. The tickling sensation is greater than the sensory threshold but less than the pain threshold. The starting point for pulse amplitude was 20 mA. During flexible cystoscopy, participants were able to change the amplitude on the TENS device at will. Placebo TENS Group: unit identical to active unit but without any nerve stimulation. Control Group: no analgesia. Electrodes: 2, type and size not detailed, each electrode was placed halfway along an imaginary line drawn from the ASIS to pubis. Duration and frequency of Rx: duration not detailed, 1 Rx. Device/manufacturer: Prometheus Group, Dover, NH. Adverse effects: 2 participants in the Active TENS group could not tolerate the TENS unit as the amplitude was gradually increased to the starting point of 20 mA; 1 participant in the Placebo TENS group reported severe abdominal pain several hours after the procedure.
Outcomes	Pain outcome: VAS, 30 seconds and 1 min into the procedure, 5 mins after procedure finished. ITT/per protocol analysis: not detailed. Statistical analysis:  no evaluable data for this review as unclear if SD data are presented. No significant changes in VAS between groups at each of the 3 time points.
Notes	Abbreviation: ASIS‐anterior superior iliac spine
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"A total of 148 patients were prospectively randomised into one of three groups."
Allocation concealment (selection bias)	Unclear risk	No details provided.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	No details provided.
Source of funding bias	Unclear risk	No details provided.
Blinding (Participant)	High risk	It is impossible to adequately blind participants who receive electrical stimulation. Text says it was a double‐blind study but no details provided ‐ assume they intended to blind the participants. The placebo TENS group was described as "a control group with a placebo TENS unit (unit identical to active unit but without any nerve stimulation)". The inclusion/exclusion criteria did not state that participants had to be TENS naïve. Control group received no treatment so these participants could not be blinded.
Blinding (Outcome Assessor)	Unclear risk	Text states that it was a double‐blind study but no details provided if the outcome assessor was blinded.
Sample Size	High risk	TENS (N = 48); placebo TENS (N = 49); control (N = 51).