N the VT and AP direction were also significantly correlated with this clinical test. Postural Stability Measures Modality Findings Disease Duration (Years) NonFreezer 6.7?.2 Freezer 7.5?.ArticleExperimental Groups N (Mean Age ?SD) Hoehn Yahr Non-Freezer = 2.4 ?.5 Freezer = 3.2 ?.8 UPDRS III– OFF NonFreezer = 42.3 ?2.9 Freezer = 46.2 ?2.2 UPDRS III– ON NonFreezer = 35.6 ?2.8 Freezer = 36.3 ?1.7 Hoehn Yahr Non-Faller = 2.4 ?.5 Faller = 2.9 ?.8 Non-Faller 5.2?.1 Faller 6.1 ?.0 3D Accelerometer Freq: 100 Hz Lower back Harmonic ratio (HR) Anteroposterior (AP) Mediolateral (ML) Vertical (VT) Stride regularity Anteroposterior (AP) Mediolateral (ML) Vertical (VT) Width of dominant frequency Anteroposterior (AP) Mediolateral (ML) Vertical (VT) Gait Gait Step regularity Stride regularity Step symmetry Stride length variability Stride timing variabilityWeiss 2014 [35]PD Freezer vs. Non-Freezer: NonFreezer = 44 (66.5 ?.8) Freezer = 28 (64.4?.7)PLOS ONE | DOI:10.1371/journal.pone.0123705 April 20, 2015 During a 3-day assessment of gait and mobility, fallers exhibited reduced HRs in both the AP and VT directions. PD fallers also had less VT stride regularity than nonfallers and a greater width of the dominant frequency for the AP and VT directions. Hoehn Yahr PD = 2? Not Reported 3D Accelerometer Freq: 50 Hz Lateral pelvis 1D Gyroscopes Freq: 200 Hz Anterior shank 2D Gyroscopes Freq: 200 Hz Wrist Inertial Sensor Freq: 200 Hz Sternum There were no significant differences observed in step regularity, stride regularity or step symmetry between PD patients and controls. Timed Up and Go PD and control groups did not differ with respect to stride length variability or stride time variability. Hoehn Yahr PD = 1.6?.5 UPDRS III PD = 20.0?.4 PD 1.1 ?.1 Wearable Sensors for order Q-VD-OPh Assessing Balance and Gait in Parkinson’s DiseaseWeiss 2014 [31]PD Fallers vs. Non-Fallers: NonFaller = 67 (64.0 ?.8) Faller = 40 (66.5?.2)Yang[23]PD = 5 (78.0?.8) Control = 5 (26.0 ?.1)Zampieri 2009 [28]PD = 12 (60.4?.5) Control = 12 (60.2 ?.2)PD: Parkinson’s disease; PSP: Progressive supranuclear palsy; IPD: Idiopathic Parkinson’s disease; VPD: Vascular Parkinson’s disease; HRPD: People at high-risk of Parkinson’sdisease; UPDRS: Unified Parkinson’s Disease Rating Scale; MDS-UPDRS: Movement Disorders Society’s CGP-57148B dose revision of the Unified Parkinson’s Disease Rating Scale; Freq: Sampling frequency of wearable sensordoi:10.1371/journal.pone.0123705.t12 /Wearable Sensors for Assessing Balance and Gait in Parkinson’s Diseaseidentified five additional papers for consideration. Following full-text review of the remaining 44 studies, a further 18 studies were excluded, including one that was unattainable, three that had no control group or condition and 14 that had no sensor-based measure of standing balance or walking stability. The remaining 26 articles were selected for inclusion in this systematic review.Study Design and Methodological QualityAll 26 studies included within this review had a cross-sectional research design with a broad aim of using different types of wearable sensors to observe or identify differences in standing balance or walking stability for Parkinson’s disease compared with controls or a control condition (e.g. on medication vs. off medication, PD subtypes). Given their cross-sectional nature, ten items were excluded from the methodological quality checklist, as they specifically targeted qualities that are unique to intervention studies. The decision to exclude thes.N the VT and AP direction were also significantly correlated with this clinical test. Postural Stability Measures Modality Findings Disease Duration (Years) NonFreezer 6.7?.2 Freezer 7.5?.ArticleExperimental Groups N (Mean Age ?SD) Hoehn Yahr Non-Freezer = 2.4 ?.5 Freezer = 3.2 ?.8 UPDRS III– OFF NonFreezer = 42.3 ?2.9 Freezer = 46.2 ?2.2 UPDRS III– ON NonFreezer = 35.6 ?2.8 Freezer = 36.3 ?1.7 Hoehn Yahr Non-Faller = 2.4 ?.5 Faller = 2.9 ?.8 Non-Faller 5.2?.1 Faller 6.1 ?.0 3D Accelerometer Freq: 100 Hz Lower back Harmonic ratio (HR) Anteroposterior (AP) Mediolateral (ML) Vertical (VT) Stride regularity Anteroposterior (AP) Mediolateral (ML) Vertical (VT) Width of dominant frequency Anteroposterior (AP) Mediolateral (ML) Vertical (VT) Gait Gait Step regularity Stride regularity Step symmetry Stride length variability Stride timing variabilityWeiss 2014 [35]PD Freezer vs. Non-Freezer: NonFreezer = 44 (66.5 ?.8) Freezer = 28 (64.4?.7)PLOS ONE | DOI:10.1371/journal.pone.0123705 April 20, 2015 During a 3-day assessment of gait and mobility, fallers exhibited reduced HRs in both the AP and VT directions. PD fallers also had less VT stride regularity than nonfallers and a greater width of the dominant frequency for the AP and VT directions. Hoehn Yahr PD = 2? Not Reported 3D Accelerometer Freq: 50 Hz Lateral pelvis 1D Gyroscopes Freq: 200 Hz Anterior shank 2D Gyroscopes Freq: 200 Hz Wrist Inertial Sensor Freq: 200 Hz Sternum There were no significant differences observed in step regularity, stride regularity or step symmetry between PD patients and controls. Timed Up and Go PD and control groups did not differ with respect to stride length variability or stride time variability. Hoehn Yahr PD = 1.6?.5 UPDRS III PD = 20.0?.4 PD 1.1 ?.1 Wearable Sensors for Assessing Balance and Gait in Parkinson’s DiseaseWeiss 2014 [31]PD Fallers vs. Non-Fallers: NonFaller = 67 (64.0 ?.8) Faller = 40 (66.5?.2)Yang[23]PD = 5 (78.0?.8) Control = 5 (26.0 ?.1)Zampieri 2009 [28]PD = 12 (60.4?.5) Control = 12 (60.2 ?.2)PD: Parkinson’s disease; PSP: Progressive supranuclear palsy; IPD: Idiopathic Parkinson’s disease; VPD: Vascular Parkinson’s disease; HRPD: People at high-risk of Parkinson’sdisease; UPDRS: Unified Parkinson’s Disease Rating Scale; MDS-UPDRS: Movement Disorders Society’s revision of the Unified Parkinson’s Disease Rating Scale; Freq: Sampling frequency of wearable sensordoi:10.1371/journal.pone.0123705.t12 /Wearable Sensors for Assessing Balance and Gait in Parkinson’s Diseaseidentified five additional papers for consideration. Following full-text review of the remaining 44 studies, a further 18 studies were excluded, including one that was unattainable, three that had no control group or condition and 14 that had no sensor-based measure of standing balance or walking stability. The remaining 26 articles were selected for inclusion in this systematic review.Study Design and Methodological QualityAll 26 studies included within this review had a cross-sectional research design with a broad aim of using different types of wearable sensors to observe or identify differences in standing balance or walking stability for Parkinson’s disease compared with controls or a control condition (e.g. on medication vs. off medication, PD subtypes). Given their cross-sectional nature, ten items were excluded from the methodological quality checklist, as they specifically targeted qualities that are unique to intervention studies. The decision to exclude thes.
