Truong 2010.

Methods	Randomised, double‐blind, parallel design Randomisation: pre‐generated randomisation code Setting: multicentre (16 centres in USA, 4 in Russia) Duration: 12 weeks
Participants	116 participants enrolled (BtA group = 55; placebo group = 61) % Female: BtA: 67%; placebo: 62% Mean age, SD: BtA: 51.9, 13.4; placebo: 53.9, 12.5 Mean CD duration, SD: BtA: 12.0 years, 8.8; placebo: 11.8 years, 8.8 Mean CD severity, SD (TWSTRS total): BtA: 43.8, 8.0; placebo: 45.8, 8.8 Inclusion criteria: reported symptoms for ≥ 18 months TWSTRS total score ≥ 30, TWSTRS severity subscale score ≥ 15, and TWSTRS disability subscale score ≥ 3 previously untreated with Bt, or previously treated with Bt with a minimum interval of 16 weeks since the last injection or a return to pre‐treatment status Exclusion criteria: pure anterocollis or retrocollis apparent symptom remission at screening previous poor response to Bt current treatment with BtB due to lack of efficacy of BtA or the presence of neutralising antibodies to BtA myasthenia gravis, other disease of the neuromuscular junction, or symptoms that could interfere with TWSTRS scoring use of muscle relaxants and benzodiazepines if not on a stable dosage for 6 weeks prior to study treatment known hypersensitivity to Bt or related compounds; total body weight < 100 lbs (45.4 kg) pregnant or lactation previous phenol injections to the neck muscles, myotomy or denervation surgery involving the neck or shoulder region cervical contracture that limited passive range of motion
Interventions	BtA: Dysport (abobotulinumtoxinA) Placebo: not described Study drug preparation: BtA provided in vials by Ipsen Muscles injected: the doses and number of injection sites per muscle were determined at the discretion of the investigator EMG guidance: left at discretion of the investigator BtA dose per participant: 500 U
Outcomes	Primary outcome: TWSTRS total score at week 4 Secondary outcomes: TWSTRS total and subtotal scores at weeks 8 and 12 Investigator assessment of symptom severity using a VAS, participant Assessment of Symptom Severity using a VAS Pain VAS scores Short Form 36 quality‐of‐life questionnaire scores Investigator Assessment of Overall Treatment Successes (Global Assessment of Efficacy ratings of ‘better’ or ‘much better’, and a Global Safety Assessment of no worse than 'Moderate') Adverse events Plasma neutralising antibodies
Notes	Study discontinuations, reasons: BtA: n = 10 (18%), lack of efficacy: n = 5, consent withdrawal: n = 2, lost to F/U: n = 1, unrelated reasons: n = 2 Placebo: n = 23 (38%), lack of efficacy: n = 23
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "In the double‐blind treatment phase, patients were randomized using a pre‐generated randomization code to receive intramuscular injection of either 500 units Dysport or placebo (1:1)"
Allocation concealment (selection bias)	Unclear risk	Comment: method of concealment not specified
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Comment: blinding not specified although study described as double‐blind
Blinding of outcome assessment (detection bias) Objective outcomes	Unclear risk	Comment: blinding not specified although study described as double‐blind
Blinding of outcome assessment (detection bias) Subjective outcomes	Unclear risk	Comment: blinding not specified although study described as double‐blind
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "Efficacy variables were assessed using intent‐to‐treat (ITT) analysis" Quote: "Safety assessments were based on the safety population, which included all patients who received at least one dose of study medication" Comment: the reasons for discontinuation were described
Selective reporting (reporting bias)	Low risk	Comment: the expected outcomes that are usually evaluated in intervention trials for this condition were reported in this study.
For‐profit bias	High risk	Quote: "This study was supported by the Ipsen Group. Editorial assistance for the preparation of this manuscript was provided by Ogilvy Healthworld Medical Education; funding was provided by Ipsen Limited, Slough, UK"
Enriched population – preferential enrolment of positive responders	High risk	Quote: "Patients were excluded if they had a (...) previous poor response to BoNT‐A or BoNT‐B treatments; current treatment with BoNT‐B due to lack of efficacy of BoNT‐A or the presence of neutralising antibodies to BoNT‐A"
Enriched population – exclusion of poor responders	High risk	Quote: "Patients were excluded if they had a diagnosis of pure anterocollis or retrocollis"