Reliability assessment of power wheelchairs.

Area of Science:

• Rehabilitation Engineering
• Reliability Engineering
• Medical Device Performance

Background:

• Power wheelchairs are essential assistive devices for mobility.
• Assessing and improving the reliability of power wheelchairs is crucial for user safety and independence.
• Existing reliability measures may not adequately capture the performance of diverse wheelchair models.

Purpose of the Study:

• To develop and evaluate novel reliability performance metrics for power wheelchairs.
• To compare the reliability of standard versus complex seating power wheelchair models.
• To analyze factors influencing wheelchair repair trends and failure rates.

Main Methods:

• Retrospective analysis of repair data from 1092 NHS-prescribed power wheelchairs (2007-2013).
• Application of repairable systems reliability analysis, including Repair Trend, Mean Time Between Failures (MTBF), and Wheelchair Reliability Index (WRI).
• Comparison of reliability between standard (S1, S2) and complex (C1, C2) seating models, stratified by age group (adults, seniors).

Main Results:

• Complex seating models (C1, C2) exhibited significantly lower reliability and different repair distributions compared to standard models (S1, S2).
• Mean Time Between Failures (MTBF) ranged from 2-8 months, with 68-80% of units failing over five years, indicating overall poor reliability.
• Significant differences in repair distributions were observed between adult and senior users, but no association with sex or specific demographic variables for recurrent repairs.

Conclusions:

• Power wheelchair reliability is suboptimal, necessitating regular condition inspections (every 3-6 months).
• Users requiring complex seating have lower reliability devices, emphasizing the need for enhanced reliability and safety standards.
• Findings support the urgent need for improved wheelchair selection, standards, servicing, and provision systems to enhance device performance and user outcomes.