Statistical analysis
NRS
Statistical justification of the sample size: a 2-point improvement of the numerical rating scale is considered to be clinically relevant [As this is the first protocol dedicated to the treatment of painful patients in a palliative care setting with tDCS, we did not find any evidence in the literature that could help us justify the number of needed patients for the evaluation of the other clinical parameters, apart from the NRS.On the basis of these hypotheses:A mean NRS difference of 2 points between the active tDCS arm and the sham tDCS arm,Standard deviation of 2.8,Power of 80%.Alpha risk of 5%,32 patients per arm would be necessary, i.e. a total of 64 patients. In order to ensure sufficient power, an additional 10% of patients will be included in the study, i.e. a total of 70 patients.The study will therefore include 70 patients: 35 in the tDCS arm and 35 in the sham tDCS arm.The variables measured on inclusion will be described for all patients and in each of the two arms by number and percentage for each modality for qualitative variables and by minimum, maximum, mean, standard deviation and quartiles for quantitative variables. The primary efficacy population will be a modified intention-to treat (mITT) population, comprising all randomized patients who have received at least one tDCS session (active or sham) and who were evaluated on D0 (baseline) and on D8.