Wong 2007.

Methods	Randomised, placebo‐controlled, double‐blind trial
Participants	55 participants who fulfilled international classification criteria for SMA types II or III Inclusion criteria: aged 2–18 years clinical diagnosis of SMA with confirmed mutations of the SMN1 gene FVC ≥ 20% of predicted for age < 15% variance on test–retest of QMT in ≥ 1 muscle group (for participants aged > 5 years) postpubertal sexually active girls must have had a negative pregnancy test Exclusion criteria: any evidence of renal dysfunction central nervous system damage neurodegenerative or neuromuscular disease other than SMA a requirement for mechanical ventilation ≥ 16 hours a day use of creatine or any experimental substance such as riluzole within 90 days of entering the study
Interventions	Creatine: aged 2–5 years, 2 g once a day or placebo; age 5–18 years, 5 g once a day or placebo Duration of treatment: 6 months Follow‐up: 9 months
Outcomes	2–5 years and 5–18 years: change in disability score (GMFM), change in quality of life, adverse events 5–18 years: change in quantitative muscle strength (QMT), change in pulmonary function
Funding	National Institutes of Health, the Muscular Dystrophy Association, and Andrew's Buddies Experimental and Applied Sciences; Golden, Colorado supplied creatine
Conflicts of interest	Not reported
Notes	Creatine group at baseline slightly weaker; follow‐up inadequate (> 20% dropout rate and < 9 months' follow‐up). Muscle strength was measured bilaterally for hand grip, elbow flexion, knee extension and knee flexion according to the Richmond Quantitative Measurement System
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomly assigned, method of randomisation unknown.
Allocation concealment (selection bias)	Unclear risk	Randomisation at central site. Method not known.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Participants, families, investigators, evaluators and study co‐ordinators blinded; the study statistician blinded to group membership.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Participants, families, investigators, evaluators and study co‐ordinators blinded; the study statistician blinded to group membership.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	High dropout rate partially described.
Selective reporting (reporting bias)	Low risk	Outcome measurements were limited and inconsistent in the published report, but the trialists provided additional data for analysis.
Other bias	Unclear risk	None identified.

CMAP: compound muscle action potential; CSF: cerebrospinal fluid; DEXA: dual energy X‐ray; ECG: electrocardiogram; FEV₁: forced expiratory volume in 1 second; FVC: forced vital capacity; GMFM: Gross Motor Function Measure; HFMS(E): Hammersmith Functional Motor Scale (Expanded); ITT: intention‐to‐treat; MFM: Motor Function Measure; MHFMS: Modified Hammersmith Functional Motor Scale; mini‐SIP: mini‐Sickness Impact Profile; MIP: maximum inspiratory pressure; MMT: manual muscle testing; mRNA: messenger ribonucleic acid; MUNE: motor unit number estimation; PedsQL: Pediatric Quality of Life Inventory; QMT: quantitative muscle testing; SMA: spinal muscular atrophy; SMAFRS: Spinal Muscular Atrophy Functional Rating Scale; SMN: survival motor neuron.