Qerama 2006.

Study characteristics
Methods	Study design: randomised, double‐blind, placebo‐controlled, parallel study Intention‐to‐treat: not used Sample size: "Pain reduction of 25 to 30% from baseline has been considered clinically relevant. Expecting the mean pain intensity at the baseline correspond to a 25 to 30% reduction of the baseline.Thus, a total of 26 participants were expected to be sufficient to obtain a statistical power greater than 90% (α = 0.05) for a parallel trial." Setting: Department of Neurophysiology, Aarhus University Hospital, Denmark Follow‐up: 28 days
Participants	N = 30 (40% male, 60% female) Mean age (years): BTXA 54.5, control 46.7 Mean pain duration (months): BTXA 26.3, control 13.9 Trigger point location, sex distribution and use of analgesics were similar in both groups
Interventions	Group 1 ‐ botulinum toxin A (BTXA) ‐ 50 units/0.25 mL of BTXA Group 2 ‐ placebo ‐ 0.25 mL of sodium chloride (0.9%) For both comparison groups units were administered via the EMG needle at the second visit. The substances were injected at the trigger point through one insertion and in 5 directions at 4 sites per direction
Outcomes	1. Median spontaneous and evoked trigger point pain intensity 2. Motor endplate activity 3. Range of motion 4. Pain relief 5. Pressure pain detection and tolerance thresholds 6. Median spontaneous and evoked referred pain intensity 7. Area of local and referred pain intensity
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"Assignment to treatment group was done randomly by means of a computer generated randomizations code, known only by the assistant (LF), who had no contact with the participants during the study."
Allocation concealment (selection bias)	Low risk	Participants were enrolled and allocated by the investigator (EQ). After completion of the study the assistant (LF) who had no contact with the participants during the study, returned the closed envelopes with information about treatment sequence.
Blinding (performance bias and detection bias) All outcomes	Low risk	Blinding was maintained until the data analysis was completed
Selective reporting (reporting bias)	Low risk	The reports of the study were free of suggestion of selective outcome reporting
Other bias	Low risk	It appears that the study was free of other problems that could put it at a high risk of bias
Size of study	High risk	N = 30 participants

BMI: body mass index
BTXA: botulinum toxin A
RCT: randomised controlled trial
U: units
VAS: visual analogue scale