Development of the Difficulty with Mobility Questionnaire: A Pilot Study

All persons presenting for one of two one-week residential O&M instruction programs (long cane 1 and long cane 2) in January and February of 2014 at Guide Dogs Queensland (GDQ) were asked to rate the level of difficulty that each of the 23 items included in the DMQ posed to them before and after participating in their O&M training program. They were also asked to rate their ability to get around on both occasions. This was done as part of the GDQ’s standard intake and discharge process. This project has been evaluated for ethical concerns by peer review, judged to be low risk and recorded on Massey University’s Human Ethics Committee Low Risk Database. Consequently, it has not been reviewed by one of the University’s Human Ethics Committees. The authors are responsible for the ethical conduct of this research. If there are any concerns about the conduct of this research that you wish to raise with someone other than the authors, please contact Professor John O’Neill, Director (Research Ethics), telephone +64 6 350 5249, e-mail humanethics@massey.ac.nz.

Thirty-two persons presented for O&M instruction during this time period. They ranged in age from 20 to 82 (mean age = 53.9) and 40% were male. All met the Guide Dogs Queensland criteria that a person is eligible to receive rehabilitation services from GDQ when: The person has a vision loss that is permanent or likely to be permanent (i.e., irreversible, chronic, is not responsive to intervention measures, not corrected by spectacles); AND the vision loss results in a substantial reduction of the person’s capacity to be safely and independently mobile (Eligibility for Rehabilitation Services Policy: Guide Dogs Queensland). In response to the question ‘How much usable vision would you say you have?’ 4 persons (12%) reported having none, 25 (79%) a little and 3 (9%) a lot.

The DMQ consisted of 23 items identified as either a hindrance to non-visual travel or as a point of intervention for O&M training in a review of O&M related literature (Barlow, Bentzen, Sauerburger, & Franck, 2010; Brouwer, Sadlo, Winding, & Hanneman, 2008; Deverell, Taylor, & Prentice, 2009; Hill & Ponder, 1976; La Grow & Blasch, 1992; La Grow & Long, 2011; Jacobson, 2013; Long, McNeal, & Griffin-Shirley, 1990; Long, Reiser, & Hill, 1990; Smith, De l’Aune, & Geruschat, 1992; Yablonski, 2000). The 23 difficulty items were presented following the root question ‘How much difficulty would you say you have in completing the following tasks?’ and available responses ranged from 1 ‘none at all’ to 5 ‘an extreme amount’. The possibility to reply ‘not applicable’ was also made available for the instances when an individual genuinely had no opportunity to perform a given task (i.e., using public transportation). Table 1 illustrates the format and response options for the 23 DMQ items.

Table 1.

In addition, a single-item measure of ability to get around (AGA) was administered both pre and post intervention. This measure was drawn from the World Health Organization Qualify of Life BREF (WHO, 1996). The question posed was ‘How well are you able to get around?’ with available responses ranging from 1 ‘Very poorly’ to 5 ‘Very well’. The use of this item as a global measure of mobility is well established (La Grow, Alpass, Stephens, & Towers, 2011; La Grow, Yeung, Towers, Alpass, & Stephens, 2011, 2013; Yeung, La Grow, Towers, Alpass, & Stephens, 2011). The AGA score was administered as a means to assess the concurrent validity of the DMQ.

The DMQ was assessed for reliability, validity, and sensitivity. Reliability, a measure of consistency, is a necessary but not sufficient condition to establish the validity of a measure. Reliability of the DMQ was assessed using Cronbach’s alpha coefficient, a commonly used measure of internal consistency (Pallant, 2011). Cronhach’s alpha coefficient should be above 0.7 for the measure to be considered reliable (DeVellis, 2003). Validity reflects the degree to which an item or a battery of items appear to measure what they are supposed to measure (i.e., in this case a reduction in difficulty with independent travel gained by participating in an O&M program for blind and vision impaired persons). Two measures of validity were used in this study; face validity (the degree to which the measure looks like it is measuring what is supposed to be measuring) and concurrent validity (the extent to which scores on the measure of interest correlate with scores on a measure of a related construct). Face validity of the measure was evaluated by presenting each of the 23 DMQ items and the single measure of AGA to three different focus groups for evaluation; clients currently undergoing an O&M program at GDQ (n=3), clients who had completed an O&M program at GDQ in the last 5 years (N=5), and O&M instructors employed by GDQ (N = 4). The groups met separately and were asked to focus on each of the 23 separate items of the DMQ, the root question and the response category available in DMQ, as well as, the separate AGA item. They were specifically asked if each of the DMQ items were relevant to their mobility, if the root question asking them to rate the difficulty of the task was a reasonable way to address these tasks, if they felt any item should be excluded or if other items should be included and whether they thought the AGA item was reflective of overall mobility. Concurrent validity of the DMQ was assessed in this study by determining the extent to which the total score for the DMQ (i.e., the sum of the separate difficulty items) and the scores for each of the separate difficulty items correlated with the AGA score.

The evaluation of reliability and concurrent validity was conducted using pretest scores only. The measure of sensitivity was conducted using both pre and post-test scores.

Sensitivity of each of the 23 difficulty items, the total mean difficulty score and the single AGA score were assessed to determine if they would reflect change following O&M instruction (in this case a one-week residential O&M program). This was done by comparing pretreatment to post-treatment scores using paired samples t-tests.

The DMQ has been proposed as an O&M outcome measure. This measure is viewed as a constellation of loosely related items which have been identified as being the focus of various aspects of O&M instruction and, therefore, may be expected to be positively impacted by the provision of a comprehensive O&M program. The results of this study provide an initial indication that the DMQ, as currently constructed, has sufficient reliability, validity, and sensitivity to justify its use as an outcome measure for O&M instruction. The Cronbach’s alpha found for this measure indicates that the internal consistency is high for both the measure as a whole and for each of the items included in the battery. The removal of only one item (travelling on lifts) would have resulted in little meaningful increase in the overall alpha of the measure, the removal of two others (negotiating stairs and travelling in familiar outdoor environments) would have no effect on overall alpha, and the removal of any of the rest would have lowered it. The response of the three focal groups indicated that the DMQ appeared to be measuring what they thought should be measured in relation to their individual O&M and that the AGM score did seem to be a reasonable measure to compare it to. The total mean score for the DMQ was strongly related to the AGM reflecting good concurrent validity. Finally, the DMQ appears to be reasonably sensitive to change occurring as a result of O&M instruction. The mean total DMQ score and the scores from 20 of the 23 individual difficulty items were found to be significantly different following the completion of a one-week residential O&M program (either Long Cane 1 or 2). It is important to note that these programs (i.e., Long Cane 1 and 2) were discrete parts of an overall O&M program of instruction which may consist of on-going domiciliary instruction (i.e., home-based instruction), Long Cane 1 and Long Cane 2, night lessons, public transport lessons, and other programs of varying length provided to teach the use of various electronic travel and orientation aids. As a result, the intervention used here to determine the sensitivity of this measure should in no way be thought of as representing a full O&M program nor should the change in scores seen here be thought of as reflecting the quantum of change that may occur from before having an instruction to that obtained following the completion of a comprehensive O&M program.

There are a number of limitations to this study which need to be highlighted. First, the study was conducted with just 32 participants; many more will be needed before further and full psychometric assessment of the DMQ can be carried out. Second, the intervention used was not illustrative of a full mobility program, but rather just a small part of one. Third, no control groups were used to ensure that the change observed in the scores from pre to post were in fact due to the provision of the intervention and not simply the result of the passage of time or a placebo effect.

The DMQ is intended to provide O&M programs with a targeted indicator of the effectiveness of instruction on clients’ ability to move around their environments, while providing the capacity to assess which individual aspects of mobility (e.g., avoiding obstacles in your path of travel, identifying drop-offs) that specific programs of instructions more effectively target (e.g., basic or advanced long cane instruction). Further data collection is currently being undertaken with Guide Dogs Queensland on a larger sample that has completed a full program of instruction in order to assess that the DMQ is an adequate outcome measure for O&M instruction. With this expanded dataset we also aim to assess whether various DMQ items will cluster around a number of discrete constructs and thus underpin the development of brief DMQ versions for O&M program use.