E criteria was made to ensure that the overall quality of the studies included in this review was not unfairly biased by these items that were not relevant to their chosen design. Based on the appraisal of methodology quality, eight papers were identified as being of low methodological quality (range = 31.8 to 50.0 ), 15 papers were of moderate methodological quality (range = 54.5 to 72.7 ) and three papers were of high methodological quality (range = 77.3 to 90.9 ). In general, the reviewed papers performed poorly on criteria addressing external validity (e.g. representativeness of the sample), internal validity (e.g. identification of and adjustment for potential confounders) and statistical power (e.g. no power calculation and insufficient details to make an informed appraisal).Sensor Type and PlacementMultiple wearable sensor types were used within the included articles to assess measures of standing balance and walking stability. Of these studies, 69 reported using three-dimensional accelerometers [14, 17?3, 30?7, 39, 40], 27 used inertial sensors [13, 24?8, 38], and 4 used other types of sensors [28, 29]. Similarly, there were multiple protocols described with respect to the placement of the wearable sensors on the human body. Of the 26 included studies, 85 reported placing a wearable sensor on either the lumbar or sacral region of the trunk [13, 14, 17?2, 24?7, 31?0] and 15 reported placing devices on other body landmarks (e.g. head, shank, wrist) [23, 28?0]. Details on the studies included in this review that reported using each specific type and placement of sensors are summarised in Table 1.Assessment of standing balance and walking stabilityOf the 26 included studies, 65 used wearable sensors to assess walking during clinical tests, such as the Timed up and Go Test [14, 28] or during assessments of straight-line walking at a self-selected speed [17?3, 27, 29?1, 34?6, 39]. A wide range of sampling frequencies was used to assess walking stability in the reviewed studies, with authors reporting sampling frequencies ranging between 20 and 1024 Hz. The remaining nine studies (35 ) assessed standing balance using an instrumented functional reach test [37], dynamic posturography [24] or one of many ZM241385 price pre-existing clinical tests conducted during quiet stance (i.e. the Romberg test, tandem stance, semi-tandem stance, standing with eyes open and eyes STI-571 site closed) [13, 25, 26, 32, 33, 38, 40]. Understandably, the wearable sensors used in these studies were generally set to collect data at a slower rate to those used for assessing the dynamic tasks, with reported sampling frequencies ranging from 50 to 128 Hz. The included studies reported multiple outcomes of standing balance and walking stability that were calculated from the signals provided by the wearable sensors (e.g. accelerations). OfPLOS ONE | DOI:10.1371/journal.pone.0123705 April 20,13 /Wearable Sensors for Assessing Balance and Gait in Parkinson’s Diseasethese outcomes, the most commonly-reported measures of standing balance included postural sway velocity (23 of studies) [13, 25, 26, 32, 33, 38], RMS accelerations (19 of studies) [13, 24?6, 38] and jerk (19 of studies) [13, 25, 26, 37, 38]. The most commonly-reported measures of walking stability included, the harmonic ratio (31 of studies) [14, 17, 19, 20, 22, 30, 35, 39] and stride timing variability (27 of studies) [17, 19, 22, 28?0, 36]. A summary of the studies reporting each of the outcome measures of standing b.E criteria was made to ensure that the overall quality of the studies included in this review was not unfairly biased by these items that were not relevant to their chosen design. Based on the appraisal of methodology quality, eight papers were identified as being of low methodological quality (range = 31.8 to 50.0 ), 15 papers were of moderate methodological quality (range = 54.5 to 72.7 ) and three papers were of high methodological quality (range = 77.3 to 90.9 ). In general, the reviewed papers performed poorly on criteria addressing external validity (e.g. representativeness of the sample), internal validity (e.g. identification of and adjustment for potential confounders) and statistical power (e.g. no power calculation and insufficient details to make an informed appraisal).Sensor Type and PlacementMultiple wearable sensor types were used within the included articles to assess measures of standing balance and walking stability. Of these studies, 69 reported using three-dimensional accelerometers [14, 17?3, 30?7, 39, 40], 27 used inertial sensors [13, 24?8, 38], and 4 used other types of sensors [28, 29]. Similarly, there were multiple protocols described with respect to the placement of the wearable sensors on the human body. Of the 26 included studies, 85 reported placing a wearable sensor on either the lumbar or sacral region of the trunk [13, 14, 17?2, 24?7, 31?0] and 15 reported placing devices on other body landmarks (e.g. head, shank, wrist) [23, 28?0]. Details on the studies included in this review that reported using each specific type and placement of sensors are summarised in Table 1.Assessment of standing balance and walking stabilityOf the 26 included studies, 65 used wearable sensors to assess walking during clinical tests, such as the Timed up and Go Test [14, 28] or during assessments of straight-line walking at a self-selected speed [17?3, 27, 29?1, 34?6, 39]. A wide range of sampling frequencies was used to assess walking stability in the reviewed studies, with authors reporting sampling frequencies ranging between 20 and 1024 Hz. The remaining nine studies (35 ) assessed standing balance using an instrumented functional reach test [37], dynamic posturography [24] or one of many pre-existing clinical tests conducted during quiet stance (i.e. the Romberg test, tandem stance, semi-tandem stance, standing with eyes open and eyes closed) [13, 25, 26, 32, 33, 38, 40]. Understandably, the wearable sensors used in these studies were generally set to collect data at a slower rate to those used for assessing the dynamic tasks, with reported sampling frequencies ranging from 50 to 128 Hz. The included studies reported multiple outcomes of standing balance and walking stability that were calculated from the signals provided by the wearable sensors (e.g. accelerations). OfPLOS ONE | DOI:10.1371/journal.pone.0123705 April 20,13 /Wearable Sensors for Assessing Balance and Gait in Parkinson’s Diseasethese outcomes, the most commonly-reported measures of standing balance included postural sway velocity (23 of studies) [13, 25, 26, 32, 33, 38], RMS accelerations (19 of studies) [13, 24?6, 38] and jerk (19 of studies) [13, 25, 26, 37, 38]. The most commonly-reported measures of walking stability included, the harmonic ratio (31 of studies) [14, 17, 19, 20, 22, 30, 35, 39] and stride timing variability (27 of studies) [17, 19, 22, 28?0, 36]. A summary of the studies reporting each of the outcome measures of standing b.
