Measures of change over 12 months for the four scales tested
| Scale | Mean change over 12 months | SD (baseline) | SD (change) | p Value | Effect size | Power calculation: subjects per group* | Standardised ratio: subjects per group† |
|---|---|---|---|---|---|---|---|
| FARS, Friedreich Ataxia Rating Scale; FIM, Functional Independence Measure; ICARS, International Cooperative Ataxia Rating Scale; MBI, Modified Barthel Index. | |||||||
| *The number of participants needed for a clinical trial with a treatment and placebo group assuming that the treatment slows the observed disease progression over 12 months by 50%, with 80% power and α = 0.05. | |||||||
| †Compared with a trial powered to detect a 50% reduction in disease progress, a 25% reduction would require four times as many patients per group. A 10% reduction in disease progress would require 25 times more patients in each group. | |||||||
| FARS | −9.5 | 27.9 | 9.1 | <0.001 | 0.34 | 60 | 1 |
| ICARS | −5 | 19.5 | 6.8 | <0.001 | 0.26 | 118 | 2 |
| FIM | 3.1 | 12.9 | 6.0 | 0.02 | 0.24 | 253 | 4 |
| MBI | 1.9 | 16.3 | 6.2 | NS | 0.12 | 605 | 10 |