Objective: This study aims to evaluate the accuracy of balance and walking kinematic data derived from a smartphone placed on the abdomen, compared to a lumbar inertial measurement unit, in individuals with and without Parkinson’s disease (PD).

Background: While wearable devices are widely adopted for monitoring motor symptoms in PD, the optimal sensor placement remains under debate. Patient adherence is crucial for effective long-term monitoring, making comfortable and convenient sensor configuration essential. Placing a smartphone on the abdomen presents a potentially patient friendly option. However, this sensor configuration remains to be validated against more established sensor placements.

Method: Five PD patients and five healthy controls from the OxQUIP study, wore IMUs and consumer smart devices (smartwatch and smartphone) on their wrist and around their waist. The lumbar IMU and smartphone were placed on the lower back (at the level of L5 vertebra) and abdomen region, respectively. Data were collected during simple balance and overground walking tasks. Maximum spectral coherence in the frequency band between 0.1 and 10 Hz was used to assess the inter-device agreement for the accelerometer and gyroscope in all 3 coordinates (antero-posterior, mediolateral and vertical).

Results: Maximum spectral coherence demonstrated a good to excellent (coh>0.9) inter-device agreement in both groups, both tasks (walk and balance) and in most coordinates. However, there was a slight decrease in accuracy for specific parameters in the abdomen sensor, particularly in roll rotation, during the balance test.

Conclusion: Abdomen device placement provides clinically valid movement data for PD motor symptom monitoring. Yet, caution is advised for specific parameters, as abdominal movement may introduce noise, affecting measurement accuracy. This research contributes to identifying the patient-centric device positioning without compromising data, in both people with PD and healthy individuals.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/comparative-analysis-of-trunk-sensor-placement-for-movement-data-collection-in-the-oxquip-study/