Performance metrics for power wheelchairs: a pipe dream?

Power wheelchair (PWC) users depend on their equipment to reliably transport them throughout daily activities and allow them to participate fully in community life. However, as reported by Worobey and colleagues, PWCs frequently require repairs and cause users a variety of problems, which can range from annoying to catastrophic. These authors suggest that comparing the performance of individual PWC makes and models--a PWC Consumer Reports--might be helpful to inform users and others about the relative quality of different products. Although a comparative report is an appealing idea, we suggest that producing meaningful comparisons of specific PWCs, especially complex rehabilitation PWCs, confronts significant methodologic and practical hurdles. Challenges include dealing with small sample sizes for individual products, risk-adjusting outcomes to account for systematic differences in patterns of use, specifying meaningful outcome metrics, distinguishing the contributions of manufacturers and PWC suppliers to suboptimal performance, and disentangling the myriad components of complex rehabilitation PWCs, which often carry parts from multiple manufacturers. In any case, most users have little control over their PWC selections, with the policies of health insurers and other factors largely dictating equipment choices. Considering these various concerns, we argue that producing a valid and useful Consumer Reports for PWCs will be difficult and, at least for complex rehabilitation chairs, will be of limited value.