Mercuri 2007.

Methods	Randomised, placebo‐controlled, double‐blind trial
Participants	107 participants who fulfilled international classification criteria for SMA type II Inclusion criteria: diagnosis confirmed by genetic analysis with homozygous deletion of SMN1 SMA 2 was classified according to the International Classification for SMA, based on age at disease onset and maximum function achieved, i.e. age at onset over 6 months and being able to sit unsupported but not to walk Exclusion criteria: participation in other pharmacological trials (e.g. albuterol) in the year before our trial started undergone corrective surgery for scoliosis
Interventions	Phenylbutyrate 500 mg/kg/day 7 days orally, divided in 5 doses using an intermittent schedule (7 days on and 7 days off) or placebo Duration of treatment: 3 months Follow‐up: 3 months
Outcomes	Functional score (HFMS), change in functional score. Subgroup aged > 5 years: change in muscle strength arm and leg (myometry), change in pulmonary function (FVC), adverse events
Funding	Financial support from Famiglie SMA, Italy and Associazione per lo Studio delle Atrofie Spinali Musculari Infantili (ASAMSI) Fyrklövern Scandinavia AB, Sweden provided triButyrate Medication provided by pharmaceutical company, but no details about the involvement of the company in study procedures.
Conflicts of interest	Quote: "The authors report no conflicts of interest."
Notes	Muscle strength was measured bilaterally for elbow flexion, hand grip and 3‐point pinch. Muscle strength was measured bilaterally for knee flexion and knee extension.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomly assigned. Central allocation.
Allocation concealment (selection bias)	Low risk	Central allocation. Only randomisation unit and pharmacy had access to assignment.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Only randomisation unit and pharmacy had access to assignment.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Only randomisation unit and pharmacy had access to assignment.
Incomplete outcome data (attrition bias) All outcomes	High risk	Myometry and FVC were measured in children aged > 5 years, but a different number of children were reported in the 2 groups. No report on explaining this difference. Unclear reports on adverse events. Quote: "The efficacy analyses were conducted according to the original randomization assignment (intention to treat), using the last observation carried forward approach for missing follow‐up data"
Selective reporting (reporting bias)	Low risk	There was clear evidence that reported results corresponded to all intended outcome measurements.
Other bias	Low risk	No other bias identified