Table 3: Studies of functional, QOL, and global impression outcomes after DBS in PD.

Study Functional, QOL, or global impression scaleSignificant predictorsNumber of patientsTime lapse since surgery

Welter et al., 2002UPDRS II(i) Age
(ii) Disease duration
(iii) UPDRS III
(iv) Axial motor score
(v) LED
416 months

Daniels et al., 2011PD-Q39
SF-36
(i) Daily off time (+ve)
(ii) Lower dyskinesia score (+ve)
(iii) Improvement in UPDRS III (+ve)
(iv) Improvement in psychiatric scales (+ve)
(v) Reduction of dyskinesia (−ve)
616 months

Soulas et al., 2011PD-Q39
SF-36
(i) Age
(ii) Disease duration
(iii) Depression
(iv) Less use of social support coping
416 months and 12 months

Smeding et al., 2011PDQL(i) L-dopa response at baseline (+ve)10512 months

Maier et al., 2013Subjective perceived outcome(i) Depression
(ii) Apathy
303 months

Floden et al., 2014PD-Q39(i) Depression
(ii) Single-trial learning (episodic memory)
(iii) Preoperative PD-Q39 score
(iv) Bilateral surgery (+ve)
858 months (average)

Genc et al., 2016MDS-UPDRS II
EQ-5D
CGIS
(i) Household median income125 (43 for MDS-UPDRS II and EQ-5D)6 months and 12 months

Maier et al., 2016Subjective perceived outcome(i) Apathy
(ii) Axial motor score
2812 months

Abboud et al.MDS-UPDRS II
EQ-5D
PGIS
CGIS
(i) Falls/balance dysfunction
(ii) Dyskinesia
(iii) Absence of tremors
(iv) Freezing
(v) UPDRS III
(vi) Preoperative BMI
130 (45 FOR MDS-UPDRS II and EQ-5D)6 months and 12 months

UPDRS II: Unified Parkinson’s Disease Rating Scale, part 2: activities of daily living; LED: L-dopa equivalent dose; PD-Q39: Parkinson’s Disease Questionnaire-39; SF-36: 36-Item Short Form Health Survey; PDQL: Parkinson’s Disease Quality of Life Questionnaire; MDS-UPDRS II: Movement Disorders Society-Unified Parkinson’s Disease Rating Scale, part 2: motor experience of daily living; EQ-5D: European Quality of Life 5-dimension Questionnaire; CGIS: Clinician’s Global Impression of Change Scale; PGIS: Patient Global Impression of Change Scale.