Emery 1983.

Methods	Double‐blind parallel group with stratified random sampling
Participants	8 boys with DMD aged 4 years 8 months to 9 years 6 months. Diagnosed according to clinical findings, serum enzymes, muscle biopsy; and EMG in some
Interventions	Verapamil 40 mg twice daily or placebo for 12 months
Outcomes	Vignos score (0 to 10). Motor ability (0 to 40). Muscle force in 10 bilateral muscle groups by MRC scale and ergometry. CK. 24 hr creatine. 24 hr creatinine. Assessed as difference from baseline
Notes	1 in verapamil arm developed prolonged PR interval. Study preceded by a trial of verapamil with 4 participants, of whom 2 developed prolonged PR interval
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: ‘..then randomly assigned ‘. Comment: does not describe how randomly assigned
Allocation concealment (selection bias)	Low risk	Quote: ‘then randomly assigned to either the active drug ... or placebo by a pharmacist..who was not involved in assessing the effects of the drug’ Comment: suggests a central pharmacy allocation
Blinding (performance bias and detection bias) All outcomes	Low risk	Quote:  ‘ The effects of treatment were assessed ..........without any knowledge of the results of previous assessments or of any of the biochemical findings’
Incomplete outcome data (attrition bias) All outcomes	Low risk	Comment: outcome data were complete
Selective reporting (reporting bias)	Low risk	Comment: no evidence of selective reporting
Other bias	High risk	Quote: ‘the criteria of selection were that they should live within easily travelling distance of this hospital...’ Comment: ‘this may have introduced bias because of differences in socioeconomic status and in ability to travel