Statistical analyses
12VT, sVT
SECONDARY
The sample size calculation is described in the published study ptotocol [The potential effects of sVT on the primary outcome (6MWT) were performed based on intention-to-treat (ITT), including all data recorded throughout the trial. Per-protocol analyses (PPA) were also run on the primary outcome and all secondary outcomes, excluding data associated with protocol violations.Analyses were carried out using linear mixed models based on repeated measures. The model for any given outcome included the three sequential measurements (if available) for all participants at the end of the Control period and after 12 weeks and 20 weeks of sVT (12VT and 20VT, respectively). Models included the study ID as a random factor to account for the non-independence of multiple measurements on the same participant, study period (i.e., Control, 12VT, and 20VT), and randomisation group (20 vs 25 Hz), with participant’s GMFCS level and the value of the outcome at baseline (T0) also included as covariates.In addition, the linear association between the baseline values for a given outcome and the participants’ ages at baseline were assessed using Pearson’s correlation coefficients; where a statistically significant association was observed (at Potential 2-way and 3-way interactions between the study period, randomisation group, and GMFCS level were assessed for all models, and where a significant interaction was present results were reported accordingly. However, non-significant interactions were removed from the models.Data are reported as the least-squares means (i.e., adjusted means) and respective 95% confidence intervals (CI), with pairwise differences between assessments reported as the adjusted mean differences (aMD) and the 95% CI. Compliance data are reported as the median, quartile 1 (Q1, 25th percentile), and quartile 3 (Q3, 75th percentile). The distribution of all outcomes was examined, and, where appropriate, data were log-transformed to approximate a normal distribution, with results back-transformed for reporting.Data were analysed using SAS v9.4 (SAS Institute, Cary, NC, USA). There was no imputation of missing values. All statistical tests were two-sided, with statistical significance maintained at 