Background: Fatigue is reported to occur in up to 92% of patients with multiple sclerosis (MS) and has been described as the most debilitating of all MS symptoms by 28% to 40% of MS patients.
Objectives: To assess whether carnitine (enteral or intravenous) supplementation can improve the quality of life and reduce the symptoms of fatigue in patients with MS-related fatigue and to identify any adverse effects of carnitine when used for this purpose.
Search methods: A literature search was performed using Cochrane MS Group Trials Register (09 September 2011), Cochrane Central Register of Controlled Trials (CENTRAL) "The Cochrane Library 2011, issue 3", MEDLINE (PubMed) (1966-09 September 2011), EMBASE (1974-09 September 2011), and www.clinicaltrials.gov for ongoing trials retrieval. Reference lists of review articles and primary studies were also screened. A hand search of the abstract book of recent relevant conference symposia was also conducted. Personal contact with MS experts and a manufacturer (Source Naturals, United States) of carnitine formulation was contacted to determine if they knew of other clinical trials. No language restrictions were applied.
Selection criteria: Full reports of published and unpublished randomized controlled trials and quasi-randomized trials of any carnitine intervention in adults affected by multiple sclerosis with a clinical diagnosis of fatigue associated with multiple sclerosis were included.
Data collection and analysis: Data from the eligible trials was extracted and coded using a standardized data extraction form and entered into RevMan 5. Discrepancies were to be resolved by discussion with a third reviewer, however this was not necessary.The quality items to be assessed were method of randomization, allocation concealment, blinding (participants, investigators, outcome assessors and data analysis), intention-to-treat analysis and completeness of follow up.
Main results: The search identified one ongoing randomized, placebo-controlled, cross-over trial (expected completion 2013) and one completed randomized, active-comparator, cross-over trial. In the completed study, adult patients with relapsing-remitting and secondary progressive MS were exposed to both acetyl L-carnitine 2 grams daily and amantadine 200 mg daily The effects of carnitine on fatigue are unclear. There was no difference between carnitine and amantadine for the number of patients withdrawing from the study due to an adverse event (relative risk ratio 0.20; 95% confidence interval 0.03 to 1.55) and no patients experienced a serious adverse event in either treatment group. Mortality and quality of life were not reported.
Authors' conclusions: There is insufficient evidence that carnitine for the treatment of MS-related fatigue offers a therapeutic advantage over placebo or active comparators. Results of the ongoing trial are eagerly anticipated in order to provide clarity.