Gordon 1995

Methods	A double‐blind, placebo‐controlled trial in which patients were treated with creatine vs placebo for 10 days. Before and on the last day of supplementation ejection fraction was determined by radionuclide angiography as was symptom‐limited 1‐legged knee extensor and 2‐legged exercise performance on the cycle ergometer. Muscle strength as unilateral concentric knee extensor performance (peak torque, Nm at 180degrees/s) was also evaluated twice with an interval of 14 days. Skeletal muscle biopsies were taken for the determination of energy‐rich phosphagens. Duration of follow‐up was not more than 14 days.
Participants	17 patients with heart failure (HF) aged 43‐70 years, ejection fraction (EF) < 40.
Interventions	Patients were supplemented with creatine 20 g vs placebo per os daily during 10 days.
Outcomes	Outcomes on death, total myocardial infarction, hospitalization for heart failure, or changes in blood pressure were not reported. Ejection fraction at rest (32 ± 4.1%) and during exercise (35 ± 5.7%) did not differ between groups and did not change after the ten day treatment in any of the two groups). Other outcomes: a significant increase in strength, measured through peak torque (+ 5 ± 1.5%) and one leg endurance tests (+ 21 ± 8.1%) which both significantly differed compared to baseline and placebo (p < 0.05). These improvements were linearly related to the increase in skeletal muscle creatine phosphate.
Notes	Cardiovascular Research. 30(3)(pp 413‐418), 1995.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "double‐blind randomization". Unclear because the method of randinomization is not mentioned.
Allocation concealment (selection bias)	Unclear risk	Method not mentioned.
Blinding (performance bias and detection bias) All outcomes	Low risk	Quote: "double‐blind randomization", "Since glucose was added tot the creatine supplementation, there was no taste difference between the two substances." No further details on blinding.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Not mentioned.
Selective reporting (reporting bias)	Low risk	All end points detailed.
Other bias	High risk	Diverse pathophysiology of heart failure, and diverse standard therapy for heart failure, so possible baseline imbalance. (Side) effect attribution difficult because simultaneous usage of standard therapy.