Summary of findings 8. High‐dose versus low‐dose coenzyme Q₁₀ and vitamin E for speech disorder resulting from hereditary ataxia.

High‐dose versus low‐dose coenzyme Q10 (CoQ10) and vitamin E for speech disorder resulting from hereditary ataxia
Patient or population: people with speech disorder resulting from hereditary ataxia Settings: hospital Intervention: CoQ10 and vitamin E (high dose versus low dose)
Outcomes	Illustrative comparative risks* (95% CI)		Relative effect (95% CI)	No of participants (studies)	Quality of the evidence (GRADE)	Comments
	Assumed risk	Corresponding risk
	CoQ10 and vitamin E (low dose)	CoQ10 and vitamin E (high dose)
Short‐term (1 week) percentage change (improvement) in overall speech production	See comment	See comment	Not estimable	0 (0)	See comment	Not an outcome in this study
Short‐term (within 1 month) change in isolated movement, objective and subjective measures of speech production Cooper 2008 reported 3 speech measures: ICARS speech subscale. Scale from: 0 to 8. Higher scores indicate greater clinical severity Syllable repetition (number of repetitions of "pata" per 10 seconds). Higher repetitions represent lesser speech impairment Time taken (seconds) to read a standard passage. Higher scores represent greater speech impairment Follow‐up: mean 2 years	The mean short‐term (within 1 month) change in isolated movement, objective and subjective measures of speech production in the low‐dose group was ICARS speech subscale: a decrease of 0.05 Syllable repetition: a decrease of 0.6 Standard passage: an increase of 0.7	The mean short‐term (within 1 month) change in isolated movement, objective and subjective measures of speech production in the high‐ dose group was ICARS speech subscale: 0.03 higher (0.16 lower to 0.22 higher) Syllable repetition: 0.5 higher (0.03 lower to 1.03 higher) Standard passage: 2.3 higher	Not estimable	43 (1 study)	⊕⊕⊝⊝ low1,2	No statistically significant difference was observed between groups for any speech measure
Short‐term (within 1 month) change in quality of life scores related to communication as measured by validated communication assessments	See comment	See comment	Not estimable	0 (0)	See comment	Not an outcome in this study
Longer‐term (minimum 1 month) change in generic quality of life scores	See comment	See comment	Not estimable	0 (0)	See comment	Not an outcome in this study
Adverse effects (during study)	See comment	See comment	Not estimable	50 (1 study)	See comment	No major adverse events Minor effects included increased bowel frequency (1 participant, high‐dose group) and prolonged nausea (1 participant, low‐dose group)
Longer‐term burdens (minimum 1 month) (for example, demands on caregivers, frequency of tests, restrictions on lifestyle)	See comment	See comment	Not estimable	0 (0)	See comment	Not an outcome in this study
Economic outcomes	See comment	See comment	Not estimable	0 (0)	See comment	Not an outcome in this study
*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% CI) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; CoQ10 : coenzyme Q10; ICARS: International Cooperative Ataxia Rating Scale; RR: risk ratio
GRADE Working Group grades of evidence High quality: Further research is very unlikely to change our confidence in the estimate of effect. Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. Very low quality: We are very uncertain about the estimate.

¹Results are reported for both the RCT (no significant results) and for a comparison of the treated groups with a cross‐sectional data set, which was not adequately described.
 ²The primary outcome measure was based on a subjective measure of speech quality.