Date Published: September 08, 2017
Author(s): Anand Mhatre, Daniel Martin, Matt McCambridge, Norman Reese, Mark Sullivan, Don Schoendorfer, Eric Wunderlich, Chris Rushman, Dave Mahilo, Jon Pearlman.
Premature failures of wheelchairs in less-resourced environments (LREs) may be because of shortcomings in product regulation and quality standards. The standards published by the International Organization for Standardization (ISO) specify wheelchair tests for durability, safety and performance, but their applicability to products used in the rugged conditions of LREs is unclear. Because of this, wheelchair-related guidelines published by the World Health Organization recommended developing more rigorous durability tests for wheelchairs.
This study was performed to identify the additional tests needed for LREs.
First, a literature review of the development of ISO test standards, wheelchair standards testing studies and wheelchair evaluations in LREs was performed. Second, expert advice from members of the Standards Working Group of the International Society of Wheelchair Professionals (ISWP) was compiled and reviewed.
A total of 35 articles were included in the literature review. Participation from LREs was not observed in the ISO standards development. As per wheelchair testing study evidence, wheelchair models delivered in LREs did not meet the minimum standards requirement. Multiple part failures and repairs were observed with reviewed field evaluation studies. ISWP experts noted that several testing factors responsible for premature failures with wheelchair parts are not included in the standards and accordingly provided advice for additional test development.
The study findings indicate the need to develop a wide range of tests, with specific tests for measuring corrosion resistance of the entire wheelchair, rolling resistance of castors and rear wheels, and durability of whole wheelchair and castor assemblies.
There remains a vast need for quality wheelchairs around the world. The World Health Organization (WHO) estimates that 10% of people with disabilities (around 111 million) require a wheelchair and only about 5% – 15% have access to an appropriate one, suggesting that the unmet need is approximately 95 million wheelchairs (Borg & Khasnabis 2008; Handicap International 2013; World Health Organization 2011). To address this need and improve the quality of life of wheelchair users and others with disabilities, international organisations are promoting improved accessibility to appropriate technology. For example, the United Nations Convention on the Rights of Persons with Disabilities (UN-CRPD), which has been ratified by 156 countries, specifically mentions the importance of assistive technologies (ATs) in eight of its Articles (4, 9, 20, 21, 24, 26, 29 and 32) (United Nations 2006). Article 20 of the UN-CRPD which focuses on personal mobility indicates that state parties must facilitate personal mobility for people with disabilities that is affordable, high quality and includes relevant training. Although there is widespread ratification of the UN-CRPD, progress on its implementation is hampered by lack of understanding of disability issues, provision of quality services, training, coordination and guidance to support member states to implement changes (International Disability Alliance 2010).
The additional tests suggested in this article were based on a literature review of wheelchair standards development, wheelchair standards testing and wheelchair field evaluations in LREs as well as advice from a group of experts. A detailed description of the methods is described below.
The flow chart outlining the selection process of articles is shown in Figure 2. Of the 1112 citations retrieved and 15 citations found through references of screened articles, 35 articles met the inclusion criteria and were categorised and analysed further.
Provision of appropriate, high-quality products is recommended in LREs as wheelchairs are subjected to adverse environments. Additionally, access to maintenance and repair services is limited in LREs. To ensure reliability of products, the WHO guidelines recommend conducting product testing based on ISO 7176 wheelchair standards. Current ISO test methods simulate conditions for urban paved environments and thus the development of additional test methods has been recommended for LREs based on typical conditions seen there (Borg & Khasnabis 2008). Following this recommendation, a prioritised list of tests was developed in this study through a literature review and feedback from experts to help predict wheelchair failures in LREs.
This study is limited by the variable methodologies and availability of evidence. The study pulls evidence from ISO testing studies and field evaluation studies combined with expert recommendations to determine additional product quality tests. Based on the review, a low level of evidence for products used in LREs is available to inform additional test development for LREs. Twelve research articles were included in this literature review on wheelchair testing and only two studies reported results with wheelchairs used in LREs. Although the USAID report (USAID 2014) on wheelchairs recommends ISO testing of wheelchair designs appropriate for LREs, full-fledged ISO testing studies with such designs are not yet conducted. Findings from such studies could have assisted in understanding the failures in the laboratory and directed the additional test development.
Following development of test methods, the ISWP-SWG group plans to suggest new test methods to the ISO standards committee as a new or add-on standard to ISO 7176 or as a technical specification so that they are harmonised with national standards. Product quality testing using these additional standards could then be included as part of regulatory policies that governments of less-resourced countries adopt, or as part of the WHO GATE initiative. These standards can support implementation of the UN-CRPD Article 20, which many countries around the world have agreed to adopt. Validation of the new test methods is an important step to assess correlation with performance seen in the field, and will be conducted through research studies in LREs in collaboration with manufacturers and charitable organisations. Manufacturers and wheelchair designers in LREs will be encouraged to implement ISWP test methods for testing newly designed parts, custom components and wheelchair prototypes. Parts with low testing priority will be tested as resources are available.
The goals of this work were to identify the additional wheelchair tests necessary to screen products for LREs as suggested by the WHO guidelines and Wheelchair Consensus Conference (Sheldon & Jacobs 2006; Borg & Khasnabis 2008). Through literature search and review, several studies were found that tested products on ISO 7176 laboratory tests and in LREs. However, none investigated testing products for LRE-like conditions in laboratory settings. This is the first study addressing developing standard test methods for LREs. Published evidence combined with field observations by ISWP-SWG experts indicates that wheelchairs fail in LREs in ways that would not be predicted by ISO 7176 tests. Additional test methods are required that incorporate test factors responsible for the diverse failures seen in LREs. The additional tests that were identified include testing for castor durability, corrosion because of the environmental conditions, rear wheel and castor rolling resistance and whole chair durability. The ISWP-SWG is in the process of developing and validating these additional test methods. Results from such testing can assist manufacturers and designers in understanding deficiencies in materials and in discovering design flaws that make the product unsuitable for LRE conditions. Additionally, information from test results can inform providers and clinicians in LREs regarding durability and reliability of products which can guide wheelchair selection and delivery.