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Table 5 Aim-specific statistical analysis plan

From: Internet-based vestibular rehabilitation versus standard care after acute onset vertigo: a study protocol for a randomized controlled trial

Analysis Individuals analyzed Sample size Estimated difference based on previous results mean (SD) Power Method
Between group mean VSS-SF difference at w3, w6, m3, and m12 All participants 160+160 8.1 (7.4) vs 11.5 (9.9) [13] 94% ANCOVA
Between group mean EQ-5D difference until m3 All participants 160+160 Unknown Unknown Mixed models
Between group mean EQ-5D difference at 12m All participants 160+160 Unknown Unknown ANCOVA
Between group mean DHI difference until m3 All participants 160+160 24.4 (20.8) vs 29.2 (21.1) [13] 54% Mixed models
Mean of means T25-FW (seconds) and timed balance tests (seconds) until m3 All participants 160+160 Unknown Unknown Mixed models
Between group mean difference of means of vHIT gain (affected side) at w6 and m3 Participants at sites with access to vHIT 80+80 0.52 (0.24) vs 0.69 (0.25)a [31] 99% Ranked ANCOVA
Proportion with catch-up saccades on vHIT (affected side) at w6 and m3 Participants at sites with access to vHIT 80+80 Unknown Unknown Binary logistic regression
Body sway until m3 All participants 160+160 Unknown Unknown Mixed models
Enhanced gait and body sway analysis until m3 Umeå participants only 25+25 Unknown Unknown Mixed models
Total steps since last visit at w6 and m3. All participants 160+160 Unknown Unknown ANCOVA
Self-reported vestibular rehabilitation compliance until
6w (mean number of training sessions)
All participants 160+160 Unknown Unknown Mixed models
Proportion with falls or fractures All participants 160+160 Unknown Unknown Binary logistic regression
Proportion with BPPV All participants 320 Estimated frequency 10% N/A Binary logistic regression
  1. Abbreviations: VSS-SF vertigo symptom scale short form, EQ-5D EuroQol five-dimension scale, DHI dizziness handicap inventory, T25-FW timed 25-foot walk test, SD standard deviation, vHIT video head impulse test, w6 6 weeks, m3 3 months, m12 12 months
  2. aPower calculations based on mean gain differences before and after vestibular rehabilitation