Anthropometry of Wheeled Mobility Project: Final Report

2.1 Participant Recruitment and Sampling

A sample of 495 WhMD users was recruited for the study. These included sub-samples of manual wheelchair users, conventional powered wheelchair users and scooter users. We intentionally oversampled powered wheelchair users in order to capture the sizes and space requirements of this group.

It would be useful to know how our sample compares to national estimates of the WhMD population. The most recent published estimates on the type of device are provided by LaPlante and Kaye (2010), and Cooper and Cooper (2003). LaPlante and Kaye (2010) used data from the 1994‒95 National Health Interview Survey on Disability (NHIS-D). More recent data available on the utilization of WhMD’s (e.g. the 2010 U.S. Census Bureau’s Survey of Income and Program Participation) do not distinguish between the types of electric WhMDs. Based on estimates by LaPlante and Kaye (2010), powered wheelchair users and scooter users each comprise about 9% of the WhMD user population not residing in institutions. A representative sample of 495 WhMD users would therefore include only 45 powered wheelchair and 45 scooter users.

In a review on wheeled mobility demographics, Flagg (2009) cites estimates by Cooper and Cooper (2003) on the proportion of mobility devices in the three categories. They estimated powered wheelchairs and scooters each to be about 15% of the WhMDs in use. The estimates by Cooper and Cooper (2003) were based on their own research and experience in the field, and include wheelchairs used in institutional settings like long term care facilities, rehabilitation hospitals and assisted living facilities. In our research, we recruited from assisted living facilities and day care programs for frail older adults but only people who could propel a chair independently were eligible to participate.

Based on this larger estimate, a sample of 495 WhMD users representative of the U.S. in terms types of WhMD used would include only about 74 power wheelchair and 74 scooter users. Even this larger estimate would not allow an accurate characterization of the sizes and functional abilities of these user groups in our study, which we expected to be quite diverse and different than manual wheelchair users.

Our approach allowed us to accurately describe the range of body sizes and functional abilities of conventional powered wheelchair users and manual wheelchair users. A sub-sample of scooter users was recruited to provide us with preliminary anthropometric data for this group but we were not able, despite great efforts, to recruit a large number of scooter users. It should be noted that it is possible to manipulate our current sample with the use of statistical simulation methods to develop samples that representative in terms of device type, age, and gender (Paquet et al., in preparation).

Data were collected in three different locations to help ensure a diverse sample of WhMD users: Buffalo and its suburbs (n=351), Pittsburgh (n=100) and Ithaca (n=44). Researchers at each of these sites were trained in the data collection methods and used the same measurement equipment to ensure consistency in measurement methods across sites.