Development and Psychometric Properties of the Ambulatory Self ...

Clinical Section Gerontology 2007;53:373–381 DOI: 10.1159/000104830

Received: October 23, 2006 Accepted: April 23, 2007 Published online: June 29, 2007

Development and Psychometric Properties of the Ambulatory Self-Confidence Questionnaire Miho Asano a William C. Miller a, b Janice J. Eng a, b a School of Rehabilitation Sciences, University of British Columbia, and b Rehabilitation Research Laboratory, G.F. Strong Rehabilitation Centre, Vancouver, B.C., Canada

Key Words Ambulation Confidence Older adult Self-report questionnaire

Abstract Background: Ambulation is one of the most important elements of mobility, and difficulty with ambulation is often cited as a common problem among older adults. Self-report assessments (e.g. walking confidence) provide complementary information to performance tests (e.g. the Timed Up and Go Test, TUG) because they offer data not obtainable from a test of walking performance. Objective: To develop and assess the reliability and the content and construct validity of the Ambulatory Self-Confidence Questionnaire (ASCQ), a new measure of walking confidence. Methods: This descriptive methodological study used data from two samples. The first sample included 31 individuals (13 community-dwelling older adults, aged 65 years and older and 18 academics, clinicians, and researchers working in the area of ambulatory care and geriatrics and medicine) who assisted in establishing the content validity. Participants were asked to complete two surveys to assess the content of the ASCQ. For the second sample 101 community-dwelling older adults (665 years old) were recruited, from community centers, senior day centers, and geriatric clinics in order to determine the reliability and construct validity of the ASCQ. The ASCQ was completed twice over a 2-week interval while

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other measures such as the TUG, the 6-Min Walk Test (6MWT), the Activities-specific Balance Confidence scale (ABC) and the Instrumental Activities of Daily Living scale (IADL) were completed once in order to assess validity. Results: Group consensus was obtained for a 22-item version of the ASCQ. Of the 101 participants recruited for the project, 67 provided complete information for test-retest reliability and 91 provided information for assessment of validity. Internal consistency (Cronbach’s = 0.95) and test-retest reliability (ICC1.1 = 0.92; 95% confidence interval (CI) 0.87, 0.95) were excellent. The ASCQ was: (1) highly correlated with the ABC scale ( = 0.87); moderately correlated with the TUG ( = –0.46) and the 6MWT ( = 0.36); and weakly correlated with the IADL ( = 0.27). Conclusion: The ASCQ is reliable and support for validity is evident for this sample of communitydwelling older adults. Further studies are needed to assess the reliability and validity in a frailer older adult sample. The ASCQ may be useful to clinicians and researchers alike for determining an older adult’s confidence with their walking ability. Copyright © 2007 S. Karger AG, Basel

Introduction

Mobility is reported to be the most common disability among older adults [1, 2]. Ambulation or the ability to ‘walk’, is one of the most critical aspects of mobility and William C. Miller Rehabilitation Research Laboratory G.F. Strong Rehabilitation Centre 4255 Laurel St., Vancouver, B.C. V5Z 2G9 (Canada) Tel. +1 604 737 6314, Fax +1 604 714 4168, E-Mail [email protected]

is important in order to maintain a healthy lifestyle and a good quality of life [3–5]. Regaining and maintaining ambulation is considered to be an important goal for older adults who go though hospitalization and rehabilitation [6, 7]. Accordingly, assessment tools designed to describe and evaluate ambulation are critical. One of the most popular methods to assess an individual’s ambulation is through the use of performance-based tests (i.e. walk, gait, or balance test). However, some of these tests (such as the 6-Min Walk Test) require supervision, dedicated space and/or equipment. More importantly, walk tests are usually carried out in a safe and controlled environment that seldom reflects an individual’s actual living circumstances. Self-report questionnaires provide complementary information to performancebased assessments and they have the advantage of being able to capture an individual’s perception of their ability. Moreover, such questionnaires are considered to be timeand cost-effective, as well as valid and reliable methods of data collection [8]. Perceived self-efficacy is defined as one’s beliefs about his or her capabilities to produce actions [9–15]. An individual’s perception or cognitive appraisal is believed to influence their decision to engage in a particular behavior or activity, and how well they perform the activity under given conditions [10–15]. Studies have shown that an individual’s belief in their ability is a powerful predictor of performance or behavior, regardless of whether they have the ability or not. For example, Taylor et al. [10] demonstrated that post-coronary patients’ cardiovascular recovery was improved by patients’ belief in their physical performance and cardiac function. Holman and Lorig [11] found that by increasing rheumatoid arthritis patients’ perceived self-efficacy, their patients were more motivated to participate in regular physical activities. More recently, Cheng and Boey [16] reported that a 3month cardiac rehabilitation program showed improvement in self-efficacy of activity and exercise tolerance. Furthermore, Hellstorm et al. [17] demonstrated that self-efficacy was a strong predictor of activities of daily living (ADL) performance among stroke patients and recommended that self-efficacy intervention be included as a part of rehabilitation programs. Other studies suggest that some older adults avoid venturing out into the community and limit the distance they walk based on their belief in their capability [18, 19]. Given the value that older adults place on ambulation and the importance of self-efficacy [20], a measure of ambulation confidence would be useful.

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A recent review of the literature, using CINAHL, EMBASE, and MEDLINE databases, revealed that there is no questionnaire that exclusively focuses on the assessment of confidence in ambulation; therefore, we developed the Ambulatory Self-Confidence Questionnaire (ASCQ). The purpose of this article is to present the results of a two-phase study designed to develop (phase 1) and assess the psychometric properties (phase 2) of the ASCQ. The specific objectives were to assess: (1) the content validity; (2) the internal consistency; (3) the 2-week test-retest reliability, and (4) the construct validity of the ASCQ.

Methods

Phase 1: Content Validity Study Content Validity Sample In an effort to address our first objective to assess the content validity and refine the ASCQ, a descriptive survey design was used. A total of 51 invitations were mailed to academics (including graduate students), practitioners (occupational therapists, physicians, physiotherapists, recreation and exercise therapists and medical doctors) and older adults. We purposely targeted individuals who: (1) were familiar with the assessment of ambulation or walking skills, or (2) had ‘expert’ knowledge and/or personal experience about ambulation or walking skill-related measurement tools. Older adults were also invited to provide expert opinion and feedback if they: (1) lived in the community; (2) were 665 years of age; (3) could comprehend English, and (4) were capable of walking with or without a walking aid. Older adults were recruited by posting advertisements on bulletin boards of local community and senior centers. Content Validity Protocol Two postal surveys were sent to the participants to determine how well the ASCQ represented the construct of ambulation confidence. The first survey package included an introductory letter about the study requirements, consent form, version 1 of the ASCQ, a questionnaire about the ASCQ, and a self-addressed stamped return envelope. If no response was received within 14 days of the initial mailing, participants were sent a reminder, and a second reminder was sent if necessary at 4 weeks from the initial mailing. Approximately 1 month after receiving the information from the first survey a revised version of the ASCQ and a second questionnaire were mailed to participants for final feedback. In this second survey, the participants were asked questions similar to those on the first survey. Survey Data Demographic information, such as age, sex, profession, years of experience and specialty, was collected from the academics and clinicians. Information on the age, sex, use and type of walking aid was collected from the older adult participants. The questionnaire that accompanied the original and revised versions of the ASCQ queried if each item was: (1) clearly worded; (2) important

Asano /Miller /Eng

to the construct of ambulation confidence; (3) represented a dimension of ambulation confidence that should be captured, and (4) able to discriminate between individuals with and without walking problems related to confidence. Individuals responded using a 4-point Likert scale indicating if they 1 = strongly disagree, 2 = disagree, 3 = agree, and 4 = strongly agree. In addition, participants were asked if they would like to add, delete, or modify any of the ASCQ items and briefly comment on why and how they would like to modify or change the item(s).

Phase 2: Reliability and Construct Validity Study Reliability and Construct Validity Sample A total of 101 participants were recruited for this phase of the study. None of these participants took part in phase 1. Specifically a convenience sample was drawn from 8 locations (2 community centers, 3 senior day centers, 2 geriatric outpatient clinics, and 1 geriatric day hospital). In order to participate in the study, participants had to be: (1) 665 years of age; (2) able to speak and read English; (3) have minimal cognitive impairment, and (4) be capable of walking a minimal distance (10 m) with or without a walking aid. Folstein’s Mini Mental State Exam (MMSE) was used to screen for cognitive impairment using a cutoff score of 624. The MMSE has been reported to be a reliable and valid tool to screen for cognitive impairment in elderly populations [21, 22]. The participants were excluded if they: (1) were living in a longterm care facility, and/or (2) reported that they had suffered a major illness or accident that required medical attention and/or hospitalization during the 2-week retest period.

Measures In order to assess the construct validity, 2 walk tests and 2 selfreport scales were administered to assess hypothesized relationships with the ASCQ. 6-Min Walk Test (6MWT) The 6MWT is a functional walk test that measures an individual’s physiological or cardiovascular function and reflects the functional capacity [23, 24] and the ambulation-related function of older adults [25]. The test has been reported to have high reliability with intra-class correlation coefficients (ICC) ranging from 0.88 to 0.95 [26, 27]. Strong correlation (r = 0.71) has been reported between the 6MWT and treadmill walking performance [26] and gait speed (r = –0.73 and r = 0.61, respectively) [25] in samples of older adults. To complete the 6MWT participants walked back and forth around a cone on a 10-m path for 6 min with a goal of walking as far as possible in that time. The total distance that participants walked in meters to the nearest meter was recorded. Participants were allowed to take a rest or stop if necessary at any time during the test. Timed ‘Up and Go’ Test (TUG) The TUG, a test of basic mobility [28], requires the participant to stand from a seated position, walk 3 m, turn around, return to their seat and sit down. The time taken was recorded to the nearest 10th of a second. The TUG has excellent inter-rater (r = 0.99) and test-retest reliability (ICC = 0.98) among older adults [28]. Support for the validity of the TUG has been demonstrated through correlations with gait speed (r = 0.75), the Functional Stair Test (r = 0.59), and balance (Berg Balance Scale, r = –0.76) in an older adult sample [27].

Reliability and Construct Validity Protocol Participants provided data for this phase of the study at 2 time points approximately 2 weeks apart. After obtaining consent, all participants provided baseline data by completing a series of selfreport questionnaires and performance-based measures. All of the measures were explained and/or demonstrated to the participants prior to data collection and all measurements were administered according to the assigned standardized protocols. The order of the questionnaires and performance-based tests was randomized to control for order effects. Rest periods were provided if required. At baseline sociodemographic information including age, sex, highest level of education completed, marital status, use and type of walking aid, number of medications, comorbidities, and falls (over the past 12 months), and contact information was collected. Data collection was conducted at a place of convenience to the subject. In 9 cases, data were collected at the individual’s home. At follow-up, only ASCQ data were collected along with a series of questions designed to determine if the subject had a major illness, injury, or accident that required medical attention over the retest period. If participants had a medical condition or accident, they were also asked how many days over the past 14 days they needed to stay in bed and/or avoid participating in their regular activities. Participants completed this short questionnaire and the retest version of the ASCQ at their home and sent them back to investigators using a stamped pre-addressed envelope. To maximize response all participants were phoned 13–15 days after baseline. The protocols for both phases of this study were approved by the local Ethics Review Board.

Activity-Specific Balance Confidence Scale (ABC) The ABC is a 16-item scale designed to measure balance confidence when performing daily activities. Individuals rate their responses to the items from 0% (no confidence) to 100% (complete confidence) and a summary score is derived by calculating the overall mean. The ABC has high 2-week test-retest reliability (ICC = 0.92) and high internal consistency (Cronbach’s = 0.96) in an older adult sample [29]. Support for construct validity has been demonstrated through correlations with the Physical SelfEfficacy Scale (r = 0.49) and high correlation with the Falls Efficacy Scale (r = 0.84) [29] in a sample of older adults.

Ambulatory Self-Confidence Questionnaire


Instrumental Activities of Daily Living Scale (IADL) The IADL scale is an 8-item scale designed to assess an individual’s ability to perform instrumental activities of daily living such as banking, gardening, or preparing meals. Each item is rated 0 if dependent or 1 if independent and the total score, which is the sum of the 8 items, ranges from 0 (dependent) to 8 (independent). The IADL has been reported to be a valid and reliable tool for use in the community-dwelling older adult sample [30]. Strong correlation (r = 0.72) with the Functional Assessment Questionnaire has been reported [31]. Ambulatory Self-Confidence Questionnaire (ASCQ) The ASCQ contains 22 items. Each item is scored from 0 (not at all confident) to 10 (extremely confident) and a mean score is calculated to represent overall ambulation confidence. Participants are asked to report how confident they are in their ability

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Table 1. Descriptive data for the ASCQ items (n = 91)

Item 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

Step up onto a curb? Step down off a curb? Walk up a ramp (mild incline)? Walk down a ramp (mild incline)? Walk up a flight of stairs (4 steps or more) with a handrail? Walk down a flight of stairs (4 steps or more) with a handrail? Cross a street with a timed crosswalk (walk signal)? Cross a street without a timed crosswalk (walk signal)? Walk on an uneven sidewalk? Walk on grass? Walk on slippery ground: for example icy or wet surfaces? Walk in the dark or at night when it is difficult to see your feet? Walk through a crowded place: for example a busy street? Walk and talk to a companion at the same time? Carry small items while walking: for example a carton of milk? Stop walking suddenly to avoid an oncoming vehicle? Use an escalator? Use a moving sidewalk (one at an airport)? Walk on a moving bus? Walk from one room to another in your home? Walk a short distance without stopping: for example from your home to a car? Walk a long distance without stopping: for example from your home to a bus stop?

8.7982.35 8.5782.39 9.4081.61 9.2681.74 8.9982.26 8.7982.26 9.2581.72 8.5782.54 7.9688.00 8.4582.52 6.1283.20 7.5182.90 8.3482.34 8.6082.27 8.6082.65 8.6782.18 8.5182.80 8.4382.78 6.8683.22 9.6181.20 9.3581.86 8.7482.69

Total ASCQ score

8.5281.74

Individual item scores ranged from 0 to 10 for all items except item 20 which ranged from 1 to 10.

to walk in different environmental situations at home from one room to another and in the community such as crossing a street. See table 1 for a list of the ASCQ items.

Data Analysis Means, standard deviations and proportions are provided in order to describe the samples and provide summary information of the measures used. Phase 1: Content Validity Study Data analysis was performed using descriptive statistics with SPSS Windows version 11.5. Suitability of an ASCQ item was determined when 150% of participants were in agreement. Phase 2: Reliability and Construct Validity Study Two-week test-retest reliability and item by item test-retest reliability were evaluated using intra-class correlation coefficients (ICC1.1) calculated using one-way ANOVA. The standard error of measurement (SEM) was also reported. The SEM is the standard deviation of the measurement error, which reflects the range of scores that can be expected on retesting. The SEM provides an estimate of the measurement error in the tool. Change scores that exceed this amount can be considered to indicate real change in the ambulatory confidence. Internal consistency was calculated

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using Cronbach’s and stepwise deletion was performed to determine if the changed in the absence of any of the items. The Bland-Altman (BA) limits of agreement plot was also used to provide a visual assessment of how individual scores varied between the baseline and follow-up ASCQ scores [32]. Finally, Spearman’s rank-order coefficients were calculated to determine the correlations between the performance-based measures (TUG, 6MWT), other self-report questionnaires (ABC, IADL scale) and the ASCQ. We hypothesized that the ASCQ would have: (1) strong internal consistency (Cronbach’s = 0.90); (2) strong 2-week test-retest reliability (ICC1.1 = 0.90); (3) positive and moderate (Spearman’s = 0.40) to high ( = 0.80) correlation with ABC, IADL and 6MWT, and (4) negative and moderate to strength correlation with the TUG. A p value of ! 0.05 was considered statistically significant for this study. All data entry and analysis were performed using SPSS Windows 11.5.

Results

Phase 1: Content Validity Thirty-one participants completed the first survey and 27 completed the second survey in phase 1. The group of academic and practitioner experts (8 females and 10 Asano /Miller /Eng

Table 2. Demographic characteristics of the Phase One content validity sample

Characteristics

Mean age Gender, % male Years of experience Walking aid use, %

Older adults (n = 13) 75.6 41.7 NA 46.2

Occupational background1 Medicine Physical therapy Occupational therapist Recreational therapist Exercise physiologist Nursing Rehabilitation/medical researcher Highest education completed or pursuing1 BSc/BA MD MSc/MA PhD

Academics and practitioners (n =18) 35.7 55.6 11.3 NA %

n

33.3 33.3 5.6 5.6 11.1 5.6 5.6

6 6 1 1 2 1 1

38.9 27.8 22.2 11.1

7 5 4 2

NA = Not applicable. 1 Data regarding education and occupation background only taken for the academic and practitioner sample.

males) had an average of 11.3 8 10.4 years experience in their fields related to geriatric medicine and rehabilitation sciences. The group of the community-dwelling older adults (7 females and 6 males) had an average age of 75.6 8 7.4 years. Table 2 presents a summary of the characteristics of this sample. The results of the first survey showed that the majority (74–100% of our sample, depending on the item) of experts and older adult participants agreed that the questions were clearly worded, and that they were appropriate and important to include in the ASCQ. Additionally, they believed that the items would discriminate between individuals with or without an ambulatory problem. Approximately 90% of participants stated that the ASCQ instructions were appropriate and easy to understand; 71% agreed that there was no need to delete any items from the questionnaire; 61% suggested modification to some of the items in the questionnaire, and 52% agreed that there was no need to add additional items to the questionnaire. Some of participants suggested removal of four ASCQ items, i.e.: (1) getting in and out of a Ambulatory Self-Confidence Questionnaire

Table 3. Item responses to the phase 1 expert survey questionnaire

regarding agreement with item clarity and discrimination (n = 27) ASCQ item No.

Item clarity

Item discrimination

agree1

disagree

agree

disagree

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

25 25 26 26 24 26 26 26 26 25 25 26 24 26 25 26 25 26 25 26 26 26

2 2 1 1 3 1 1 1 1 2 2 1 3 1 2 1 2 1 2 1 1 1

24 23 25 24 20 25 25 24 24 21 19 25 20 25 24 22 20 24 21 23 22 22

3 4 2 3 7 2 2 3 3 6 8 2 7 2 3 5 7 3 6 4 5 5

1 Categories collapsed: agree = strongly agree/agree; disagree = strongly disagree/disagree.

car or bus; (2) sitting down and getting up from your car or bus seat; (3) riding an elevator, and (4) entering or leaving the home, because these items reflected ‘balance and strength’ rather than ‘ambulation skill’ and the infrequency with which individuals use an escalator especially when there is often the option to use an elevator. Consequently, these ASCQ items were removed from the original version of the ASCQ leaving version 2 with 22 items. Data from the 2nd survey indicated agreement that the revised 22 item scale was easy to understand and that each item, including the new items, was important and thought to distinguish between individuals with or without walking problems related to confidence. Table 3 presents a summary of the item by item responses on 2 survey questions, specifically the agreement related to item clarity and ability for the item to discriminate between individuals with and without walking problems. There were some additional suggestions to drop or add certain items; Gerontology 2007;53:373–381

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however, these were only supported by a single participant. Given the good overall support for version 2, we proceeded to phase 2 to assess the psychometric properties of the ASCQ.

Difference in times 1 and 2 ASCQ scores

3 2 1 0 –1 –2 –3

Mean times 1 and 2 ASCQ scores

Fig. 1. Bland-Altman plot of the mean versus the difference in

times 1 (baseline) and 2 (follow-up) ASCQ scores.

Table 4. Sociodemographics of the reliability and validity sam-

ple Characteristics

Validity sample (n = 91)

Reliability sample (n = 67)

Mean age Male, % Faller (the past 12 months), % Fall/s, median Medications, median Comorbidities, median Use of walking aid, % None Cane Walker Cane and walker Highest education completed, %