Research Article: Discriminatory validity of the Aspects of Wheelchair Mobility Test as demonstrated by a comparison of four wheelchair types designed for use in low-resource areas

Date Published: September 08, 2017

Publisher: AOSIS

Author(s): Karen L. Rispin, Elisa Hamm, Joy Wee.


Comparative effectiveness research on wheelchairs available in low-resource areas is needed to enable effective use of limited funds. Mobility on commonly encountered rolling environments is a key aspect of function. High variation in capacity among wheelchair users can mask changes in mobility because of wheelchair design. A repeated measures protocol in which the participants use one type of wheelchair and then another minimises the impact of individual variation.

The Aspects of Wheelchair Mobility Test (AWMT) was designed to be used in repeated measures studies in low-resource areas. It measures the impact of different wheelchair types on physical performance in commonly encountered rolling environments and provides an opportunity for qualitative and quantitative participant response. This study sought to confirm the ability of the AWMT to discern differences in mobility because of wheelchair design.

Participants were wheelchair users at a boarding school for students with disabilities in a low-resource area. Each participant completed timed tests on measured tracks on rough and smooth surfaces, in tight spaces and over curbs. Four types of wheelchairs designed for use in low-resource areas were included.

The protocol demonstrated the ability to discriminate changes in mobility of individuals because of wheelchair type.

Comparative effectiveness studies with this protocol can enable beneficial change. This is illustrated by design alterations by wheelchair manufacturers in response to results.

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Research directly comparing different health-related interventions is essential to confirm that the goals of those interventions are achieved (Horn & Gassaway 2007; Jutai et al. 2005). Comparative effectiveness research for wheelchairs intended for use in resource-limited environments is needed (Borg & Khasnabis 2008; WHO 2011).

Discriminatory validity of the AWMP was confirmed through ANOVA analysis which discerned significant differences between wheelchair types for velocity and participant response scores. The numbers and types of comment topics explained ANOVA results and added other qualitative information. Results from this study led to responsive design change confirming the value of the AWMP in providing comparative effectiveness data.

Results of this study are specific to the conditions at our study site. Although it has much in common with other sites in low-resource areas, it is of course unique as are all locations. Tracks would not be identical at other study sites, and data from other study sites could not be directly compared with this study. For example, a rough ground track on an unpaved road at one location would not be exactly like a rough ground track at a different location. A low curb which is available and often encountered at one location might be 8 cm tall, whereas a curb at another location might be 10 cm tall. In studies carried out in North America, standardised rough surfaces have been developed and used (Sasaki & Rispin 2016). However, these standardised rough surfaces are large and not easily transported to field locations in low-resource areas. In addition, they would not perfectly model conditions encountered by wheelchair users. With the AWMP, study design, each participant is compared with themselves in their community location. AWMP could be used in many locations as long as there was no intention of considering the data exactly equivalent to data collected at another location. This flexibility is necessary in real-world research and is of key importance in studies carried out in low-resource areas. The use of letter grades as anchors for the VAS tends to standardise subject response and provide an understandable value to participants, researchers and manufactures (Funk et al. 2016; Rispin et al. 2017). However, the letter grades would need to be modified by whatever grading scale is in use in the culture in which a study is carried out.

The good discriminatory validity of the AWMP enables its use in comparative effectiveness studies that can provide much needed feedback enabling wheelchair manufacturers to optimise wheelchair design. Organisations that design and manufacture wheelchairs intended for use in low-resource settings are almost always not-for-profit and have a strong commitment to meeting the overwhelming global need for wheelchairs. Designs that hinder users’ abilities to roll forward on commonly encountered rolling environments limit the positive impact of wheelchair provision. The AWMP can be used in comparative effectiveness studies for other wheelchair types to inform beneficial design change. If AWMP studies are performed with locally available wheelchairs in locations where wheelchair users live, results could enable informed choices for wheelchair provision. Other stakeholders such as granting or charitable agencies providing funding could also benefit from comparative effectiveness data to inform wheelchair selection choices for different locations.




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