Creatine for treating muscle disorders

Abstract

BackgroundProgressivemuscle weakness is amain symptomofmost hereditary and acquiredmusclediseases. Creatine improvesmuscle performance in healthy individuals.This is an update of our 2007 Cochrane review that evaluated creatinetreatment in muscle disorders.ObjectivesTo evaluate the efficacy of creatine compared to placebo for the treatmentof muscle weakness in muscle diseases. Search methods We searchedthe Cochrane Neuromuscular Disease Group Specialized Register (4October 2010), the Cochrane Central Register of Controlled Trials(11 October 2010, Issue 4, 2010 in The Cochrane Library), MEDLINE(January 1966 to September 2010) and EMBASE (January 1980 to September2010) for randomised controlled trials (RCT) of creatine used totreat muscle diseases. Selection criteria RCTs or quasi-RCTs of creatinetreatment compared to placebo in hereditary muscle diseases or idiopathicinflammatory myopathies.Data collection and analysisTwo authors independently applied the selection criteria, assessedtrial quality and extracted data. We obtained missing data from investigators.Main results The updated searches identified two new studies. A totalof 14 trials, including 364 randomised participants, met the selectioncriteria. Meta-analysis of six trials in muscular dystrophies including192 participants revealed a significant increase in muscle strengthin the creatine group compared to placebo, with a weighted mean differenceof 8.47%; (95% confidence intervals (CI) 3.55 to 13.38). Pooled dataof four trials including 115 participants showed that a significantlyhigher number of patients felt better during creatine treatment comparedto placebo with a risk ratio of 4.51 (95% CI 2.33 to 8.74). One trialin 37 participants with idiopathic inflammatory myopathies also showeda significant improvement in functional performance. No trial reportedany clinically relevant adverse event.In metabolic myopathies, meta-analyses of three cross-over trialsincluding 33 participants revealed no significant difference in musclestrength. One trial reported a significant deterioration of ADL (meandifference 0.54 on a 1 to 10 scale; 95% CI 0.14 to 0.93) and an increasein muscle pain during high-dose creatine treatment in McArdle disease.Authors� conclusionsHigh quality evidence from RCTs shows that short- and medium-termcreatine treatment increases muscle strength in muscular dystrophies.There is also evidence that creatine improves functional performancein muscular dystrophy and idiopathic inflammatory myopathy. Creatineiswell tolerated in these people.High quality but limited evidencefrom RCTs does not showsignificant improvement inmuscle strengthinmetabolicmyopathies.High-dose creatine treatment impaired ADL andincreasedmuscle pain inMcArdle disease.