Summary of findings for the main comparison. Hydroxytryptophan versus placebo for speech disorder resulting from hereditary ataxias.
| Hydroxytryptophan (L‐5HT) for speech disorder resulting from hereditary ataxias | ||||||
| Patient or population: people with speech disorder resulting from hereditary ataxias Settings: hospital Intervention: L‐5HT | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect (95% CI) | No of participants (studies) | Quality of the evidence (GRADE) | Comments | |
| Assumed risk | Corresponding risk | |||||
| Placebo | L‐5HT | |||||
| Short‐term (within 1 month) percentage change (improvement) in overall speech production | See comment | See comment | Not estimable | 0 (0) | See comment | Not an outcome in these studies |
|
Short‐term (within 1 month) change in isolated movement, objective and subjective measures of speech production
Wessel 1995: Mean syllable duration during rapid‐syllable repetition task. Scale from: 1 to 500. Shorter durations are better. Follow‐up: 10 months Trouillas 1995: Mean time for producing a standard sentence. Shorter durations are better. Follow‐up: 6 months |
The mean short‐term (within 1 month) change in isolated movement, objective and subjective measures of speech production in the control groups was a
2 ms increase in mean syllable duration (Wessel 1995) 0.2 s increase (Trouillas 1995) |
The mean short‐term (within 1 month) change in isolated movement, objective and subjective measures of speech production in the intervention groups was
0 ms higher (CI not calculable)1 (Wessel 1995) 0.5 s lower (0.9 s lower to 0.1 lower) (Trouillas 1995) |
Not estimable | 4
(Wessel 19953,4) 19 (Trouillas 1995) |
⊕⊝⊝⊝ very low4,5,6 | Results from Trouillas 1995 and Wessel 1995 were not comparable due to difference in outcome measurement No differences were observed after treatment in either the placebo or L‐5HT conditions in either Trouillas 1995 or Wessel 1995 |
| 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 Trouillas 1995 or Wessel 1995 |
| 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 Trouillas 1995 or Wessel 1995 |
| Adverse effects (during the study) | See comment | See comment | Not estimable | 65 (2 studies) | See comment | Minor gastrointestinal side effects in 8/39 L‐5HT and 5/39 placebo participants in Wessel 1995 and 6/14 L‐5HT and 2/12 placebo participants in Trouillas 1995. Data could not be pooled because Wessel 1995 did not break down results by condition |
| Longer‐term burdens (minimum 1 month) (for example demands on caregivers, frequency of tests and restrictions on lifestyle) | See comment | See comment | Not estimable | 0 (0) | See comment | Not an outcome in Trouillas 1995 or Wessel 1995 |
| Economic outcomes | See comment | See comment | Not estimable | 0 (0) | See comment | Not an outcome in Trouillas 1995 or Wessel 1995 |
| *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; L‐5HT: L‐hydroxytryptophan; 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. | ||||||
1CI of estimate of effect was not calculable in Wessel 1995, as no measure of variance was reported for the change. 2Cross‐over study design where the 4 participants each contributed 2 measurements (Wessel 1995). 3Only 4 of the original 19 participants with Friedreich ataxia completed the speech assessments during both arms of Wessel 1995, while only 19 of 26 participants completed Trouillas 1995. 4Missing data from Friedreich ataxia group in Wessel 1995. 5The method of allocation and blinding is not clear in Trouillas 1995. Adverse effects within the treatment arm may reduce the success of blinding of investigators or participants. 6Mean duration of a standard sentence is an insensitive measure of dysarthria (Trouillas 1995).