Evaluation of two cane instruments in older adults with knee osteoarthritis.

INTRODUCTION An estimated one-third of all older adults currently use an assistive device [1]. As the older adult population continues to grow, the demand for assistive devices will likely increase. Despite the widespread use of assistive devices, studies have found high rates of abandonment ranging from 8 to 75 percent [2]. From a clinical standpoint, assistive devices such as canes and walkers are prescribed to patients to minimize disability. The extent to which an older adult chooses to use a prescribed assistive device may influence how long he or she will remain functionally independent. One may speculate that an older adult who chooses to adopt a prescribed assistive device may develop the ability to better cope with future physical and mental challenges. Psychosocial factors may influence older adults' use of commonly prescribed assistive devices. Furthermore, these psychosocial factors may ultimately determine device adoption, retention, and/or abandonment [3]. Thus, clinicians must evaluate psychosocial factors influencing assistive device use because patients' personal beliefs often influence their ongoing compliance with use of the device [4]. A review of the literature yielded several survey instruments that have been developed to measure psychosocial factors influencing assistive device use. The Quebec User Evaluation of Satisfaction with Assistive Technology (QUEST) was developed by Demers and colleagues [5] and targets current users of an assistive device. The QUEST is designed to measure satisfaction with a broad range of assistive technology and asks respondents how satisfied they are with specific features such as weight, height, length, width, and some characteristics of the services related to the device, i.e., repairs and servicing [5]. In another study, Roelands and colleagues developed separate subscales for community-dwelling older adults living in Belgium to measure awareness, possession and use of assistive devices, attitudes toward use, self-efficacy, and intention to use assistive devices [6]. The Psychosocial Impact of Assistive Devices Scale (PIADS) [3] and the Cane Cognitive Mediator Scale (CCMS) [4] also measure perceptions of assistive device use in older adults. Both these instruments can be administered to individuals even if they are not current assistive device users, thus providing information on how an assistive device would affect them. The PIADS was developed to measure the effect of an assistive device (e.g., all categories of assistive technology and not limited to any one type) on quality of life and sense of well-being [3]. The PIADS may also be used to assess a respondent's expectations of using a device before its actual use. In contrast, the CCMS was developed to assess psychosocial factors specifically related to using a cane. The CCMS was developed based on the theory of planned behavior, which may be applied to explain the performance or nonperformance of a health behavior [4]. The theory states that the intention to perform a behavior is determined by attitudes toward the behavior, perceived social pressure, and perceived behavioral control in engaging in the behavior. For example, the use of a cane by an older adult (behavior performance) may be influenced by what his or her family thinks (perceived social pressure) and the costs of obtaining a cane (behavioral control). The aim of this study was to compare simultaneously the psychometric properties of the PIADS and CCMS in older adults with osteoarthritis (OA) of the knee. Specifically, we examined the test-retest reliability (CCMS only), internal consistency reliability, and predictive validity of these instruments in order to identify which of these instruments, or subscales of these instruments, could assist the clinician in determining a patient's willingness to use an assistive device before training. METHODS Setting and Participants The data used for this analysis were derived from a randomized crossover trial whose overall aim was to investigate the effects of cane use on spatiotemporal gait parameters in patients with knee OA. …