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High-dose CoQ10 = placebo in halting progression of Parkinson disease

Clinical Question:
Is coenzyme Q10 effective in slowing disease progression in patients with early Parkinson disease?

Bottom Line:
Coenzyme Q10 (CoQ10) was no better than placebo in slowing the progression of early Parkinson disease. This study was halted before completion because of futility. (LOE = 1b)

Parkinson Study Group QE3 Investigators. A randomized clinical trial of high-dosage coenzyme q10 in early Parkinson disease: no evidence of benefit. JAMA Neurol 2014;71(5):543-552.  [PMID:24664227]

Study Design:
Randomized controlled trial (double-blinded)



Outpatient (specialty)

The researchers in this multicenter trail evaluated the effects of CoQ10 on patients older than 30 years with all 3 cardinal signs of Parkinson disease: tremor in repose, bradykinesia, and rigidity. The patients' severity had to be such that dopaminergic therapy was not needed and was not anticipated for at least the subsequent 3 months. Additionally, patients taking any other Parkinson medications during the 2 months to 3 months were excluded. Patients received either 2400 mg CoQ10 daily (n = 196), 1200 mg CoQ10 daily (n = 201), or placebo (n = 203). Additionally, all patients received 1200 IU vitamin E daily because of reports that vitamin E enhances CoQ10absorption. The research teams evaluated the patients at baseline and then again at 1, 4, 8, 12, and 16 months. The main outcome—change on the Unified Parkinson’s Disease Rating Scale —was assessed using intention-to-treat analysis. The scale assesses 5 domains: cognition, mood and behavior, patient-assessed activities of daily living, clinician assessment of motor function, severity of symptoms, and a clinician assessment of activities of daily living. More men than women enrolled in the study (2:1 ratio) and the patients were an average of 62.5 years old. Only 7.5% of the patients were of a minority ethnic group. After approximately 2 years, the study's data monitoring and safety committee recommended to a halt of the study on the basis of futility: No benefits were seen and the results from the patients who had not yet completed the study would not alter the study outcomes, even if they all showed dramatic improvement. There were no safety concerns.


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