Change scores, relative changes and effect sizes for matched cohorts
| Change score | Relative change (%) | Effect size | ||||
| STN-DBS | MED | STN-DBS | MED | Cohen’s d | Classification | |
| PDQ-8 SI | 6.1 | –6.2 | 21.0 | –20.9 | 0.72 | Moderate |
| SCOPA-motor examination | 2.8 | –0.5 | 25.7 | –4.1 | 0.67 | Moderate |
| SCOPA-activities of daily living | 0.6 | –1.3 | 9.4 | –18.1 | 0.56 | Moderate |
| SCOPA-motor complications | 1.5 | –0.7 | 63.9 | –20.6 | 0.85 | Large |
| LEDD | 307.4 | –68.2 | 30.4 | –7.5 | 0.82 | Large |
| NMSS total score | 15.6 | –16.8 | 28.8 | –36.5 | 1.11 | Large |
| Cardiovascular | –1.6 | –0.2 | –200.0 | –11.4 | 0.74 | Moderate |
| Sleep/fatigue | 4.4 | –5.1 | 33.9 | –67.8 | 1.16 | Large |
| Mood/apathy | 2.1 | –0.7 | 33.3 | –8.9 | 0.27 | Small |
| Perceptual problems/hallucinations | 0.1 | –0.6 | 9.1 | –61.0 | 0.24 | Small |
| Attention/memory | 0.8 | –1.9 | 14.6 | –35.0 | 0.50 | Moderate |
| Gastrointestinal | –0.7 | –2.4 | –15.9 | –50.1 | 0.30 | Small |
| Urinary | 2.6 | –5.5 | 24.5 | –85.0 | 0.97 | Large |
| Sexual function | 2.0 | 0.6 | 66.7 | 12.3 | 0.25 | Small |
| Miscellaneous | 5.5 | –1 | 59.8 | –14.2 | 0.88 | Large |
Change scores and relative changes from baseline to 36-month follow-up in the STN-DBS and MED groups. Effect sizes of the between-group comparison STN-DBS versus MED (Mann-Whitney U test).
Change score = (mean testbaseline − mean test follow-up)
Relative change = (mean testbaseline − mean testfollow-up) / mean test baseline x 100.
Cohen’s d = (mean pre-post changetreatment group − mean pre-post changecontrol group) / SD pretestpooled groups.
Cohen’s d can be classified as ‘small’ (0.20≥d<0.50), ‘moderate’ (0.50≥d<0.80) and ‘large’ (d≥0.80).
Effect size for the NMSS cardiovascular domain was favourable in the MED group and for all other outcome parameters and NMSS groups in the STN-DBS group.
LEDD, levodopa equivalent daily dose; MED, standard-of-care medical treatment; NMSS, Non-motor Symptom Scale; PDQ-8 SI, 8-item Parkinson’s Disease Questionnaire Summary Index; SCOPA, Scales for Outcomes in Parkinson’s disease; STN-DBS, subthalamic nucleus deep brain stimulation.