Psychometric properties of the Arabic Activities-specific Balance Confidence scale in people with multiple sclerosis: Reliability,validity,and minimal detectable change

Abstract

BACKGROUND:

Balance and gait impairments are common disorders in people with multiple sclerosis (MS). The Activities-specific Balance Confidence scale (ABC) is one of the important measures of balance confidence that can be used in people with MS. The Arabic version of the ABC was developed and validated in other than MS population.

OBJECTIVE:

To examine the psychometric properties of the Arabic Activities-specific Balance Confidence scale (A-ABC) among patients with MS.

METHODS:

A multicenter, reliability design was used to administer the A-ABC to a convenience sample of people with MS. The test-retest reliability of the A-ABC item and total scores were examined using the intraclass correlation coefficient (ICC) and 95% confidence interval (CI). Additionally, the validity of the A-ABC with Arabic Berg Balance Scale (A-BBS), Arabic Dynamic Gait Index (A-DGI), and Barthel Index (BI) was assessed using Spearman Correlation Coefficient (r). Moreover, the minimal detectable change for the A-ABC was established in people with MS.

RESULTS:

Eighty nine patients with MS (mean [SD] age = 38 [10]; female = 58) were enrolled. The internal consistency of the A-ABC was 0.96 while the minimal detectable change was 11.28. The A-ABC (mean [SD] = 61 [29]) had significant correlations with A-BBS (r = 0.76, P < 0.05), A-DGI (r = 0.65, P < 0.05), BI (r = 0.63, P < 0.05), and age (r = –0.37, P < 0.05). Fifty-two patients (58%) completed the A-ABC twice with one week interval. Excellent test-retest reliability of the A-ABC item (ICC≥0.90) and total scores [ICC = 0.98; 95% CI (0.96–0.99)] was found.

CONCLUSIONS:

The Arabic Activities-specific Balance Confidence scale showed very good psychometric properties and can be utilized with Arabic-speaking patients with multiple sclerosis.

Keywords

Multiple sclerosis activities-specific balance confidence scale reliability validity

1 Introduction

Multiple sclerosis (MS) is a progressive neurological disorder that affects young and middle -aged adults (Cameron & Lord, 2010). The prevalence of MS has reached around 200/100.000 worldwide (Pugliatti, Sotgiu, & Rosati, 2002) with around 2.3 million people are diagnosed with MS globally (National Multiple Sclerosis Society, 2016). In Jordan, the prevalence of MS diagnoses was around 39/100,000 in 2006 and has been increased dramatically (El-Salem et al., 2006).

Imbalance and unsteadiness are common impairments that affect most of people with MS at some stage during the course of their disease (Cameron & Lord, 2010). Therefore, the prevalence of falls in people with MS has been increased dramatically and was reported to be 52% (Cattaneo et al., 2002; Finlayson, Peterson, & Cho, 2006). Moreover, people with MS have a high incidence of osteoporosis due to their use of corticosteroids and lack of general activity (Khachanova, Demina, Smirnov, & Gusev, 2006; Ozgocmen et al., 2005). Consequently, falls are more likely to lead to serious injuries and reduced quality of life in people with MS. Therefore, prediction and prevention of falls in people with MS may help avoid injury, hospitalization, and increased care needs, which may otherwise be necessary.

Activities-specific Balance Confidence (ABC) scale is a reliable and valid measurement for the assessment of balance confidence (Powell & Myers, 1995). The ABC consists of 16 items with a total score that ranges between 0 and 100, where higher score equates to higher balance confidence (Powell & Myers, 1995). According to the International Classification of Functioning, Disability and Health (ICF), the items of the ABC focus mainly on the activities and participation domain (87%) (Alghwiri, Marchetti, & Whitney, 2011). The ABC became widely used and was translated to different languages including Arabic (Alghwiri, Alghadir, Al-Momani, & Whitney, 2016), Hindi (Moiz, Bansal, Noohu, Gaur, & Hussain, 2016), Swedish (Jarlsäter & Mattsson, 2003), Chinese (Hsu & Miller, 2006), and Canadian French (Salbach, Mayo, Hanley, Richards, & Wood-Dauphinee, 2006).

The Arabic version of the ABC (A-ABC) was validated in people with vestibular disorders (Alghwiri et al., 2016) and ambulatory community-dwelling older adults (Elboim-Gabyzon, Agmon, & Azaiza, 2019) and had very good psychometric properties. However, we cannot generalize these results to all other populations since validating tools in different populations is important to be able to accurately infer from the results of the tool. Specifically, the psychometric properties of the A-ABC in people with MS need to be established because their signs and symptoms are fluctuating constantly. The nature of the MS disease causes changes in the heath-status of affected individuals which make it difficult to establish the psychometric properties of certain outcome measures. To make sure that the A-ABC can be used with this population, we need to examine the reliability of the A-ABC, the convergent validity with other well-established tools and finding out the minimal detectable change (MDC).

The aims of this study were: (1) to assess the reliability of the A-ABC total and item scores, (2) to assess the convergent validity of the A-ABC with balance, mobility, and activities of daily living measures, and (3) to find out the MDC of the A-ABC in people with MS.

2 Methods

2.1 Design and participants

A multicenter, reliability design was used to collect data from two sites in Jordan: Irbid and Amman. Ethical approval of the study was obtained and patients consented before enrollment. Patients were recruited through referral from the neurologist. Inclusion criteria were patients with a confirmed diagnosis of MS with any type, age above 18 years, and ambulatory patients. Non-ambulatory patients with MS or wheel chair users were excluded.

2.2 Procedures

Data were collected in two times. In the first time, demographic information and the Kurtzke Expanded Disability Status Scale (EDSS) (McDonald et al., 2001) for each patient were collected along with the A-ABC, Barthel Index (BI), Arabic Berg Balance Scale (A-BBS), and Arabic Dynamic Gait Index (A-DGI) to assess the convergent validity of the A-ABC. One week later, 52 patients completed the A-ABC again to examine the test-retest reliability of the total and item scores.

2.3 Outcome measures

Barthel Index (BI) is a self-report measure that evaluates the ability of individuals to perform activities of daily living and mobility activities (Wade & Collin, 1988). The BI is considered as a measure of disability that had good reliability and validity (Collin, Wade, Davies, & Horne, 1988; Wade & Collin, 1988). The BI has 10 items with a total score that ranges from 0 to 100 with higher score indicates better outcomes. BI has been used with older adults (Richards et al., 2000), people post stroke (Hsieh et al., 2007), patients after brain injuries (Liu, McNeil, & Greenwood, 2004), and individuals with neurological disorders (Rollnik, 2011).

Berg Balance Scale (BBS) is a 14-item performance-based measure of balance. The scoring of the BBS ranges from 0 to 56 with higher score indicates better balance abilities and less risk of falling. BBS has been used with older adults (Donoghue, Physiotherapy, Older People, & Stokes, 2009), people with stroke (Stevenson, 2001), traumatic brain injury (Newstead, Hinman, & Tomberlin, 2005), individuals with Parkinson’s disease (Steffen & Seney, 2008), spinal cord injury patients (Wirz, Muller, & Bastiaenen, 2010), and people with vestibular disorders (Whitney, Wrisley, & Furman, 2003). Additionally, the BBS has been translated to several language including the Arabic language (Alghwiri et al., 2016).

Dynamic Gait index (DGI) is a well-known performance-based measure for the assessment of functional stability and detection of falls (Shumway-Cook & Woollacott, 1995). The DGI was validated in many populations including older adults (Shumway-Cook & Woollacott, 2007), brain injury (Simon & Harro, 2004), vestibular disorders (Wrisley, Walker, Echternach, & Strasnick, 2003), multiple sclerosis (McConvey & Bennett, 2005), Parkinson’s disease (Dibble & Lange, 2006), and stroke (Galgon, Shelby-Silverstein, & Morris, 2004; Jonsdottir & Cattaneo, 2007). Moreover, the DGI has been translated to several language including the Arabic language (Alghwiri, 2014).

2.4 Analysis

The test-retest reliability of the A-ABC total and item scores were estimated using the ICC, model (1,1) and the 95% CI (Rankin & Stokes, 1998). An ICC of >0.75 indicates “excellent” reliability, 0.40 to 0.74 indicates “fair to good” reliability, and <0.40 indicates “poor” reliability (Rosner, 2010). Additionally, the internal consistency of the A-ABC using Cronbach’s Alpha (α) was estimated. Moreover, the minimal detectable change at the 95% confidence level (MDC₉₅) of the A-ABC was calculated using the standard error of the measurement (SEM) in the following equation of 1.96* $\sqrt{2 *}$ SEM. The standard error of measurement (SEM) was calculated by taking the square root of the within subject variance as in the following equation (SEM = SD $\sqrt{1 - ICC}$ ) (Schuck & Zwingmann, 2003).

The convergent validity of A-ABC with other balance, mobility, and activities of daily living measures was estimated using the non-parametric Spearman rank order correlation coefficient rho. A Spearman correlation coefficient of greater than 0.60 indicates strong correlation, while a range between 0.31 and 0.59 indicates moderate correlation and less than 0.30 indicates poor correlation (Cohen, 1998).

A priori power analysis was conducted using the software package, GPower (Faul, Erdfelder, Buchner, & Lang, 2009) with a power of 0.9 and an alpha of 0.05 and a correlation coefficient of 0.9. The analysis indicated that a sample size of 9 participants would be sufficient to evaluate the test-retest reliability of the A-ABC.

3 Results

Eighty nine (65% females) patients with MS (mean [SD] age = 38 [10]) were enrolled from both sites in Jordan (Amman = 73 and Irbid = 16). Most of patients in this study were from the relapsing remitting type of MS (93.3%) whereas 4 of them (4.5%) had secondary progressive and only 2 of them (2.2%) had primary progressive type of MS. The mean (SD) score of EDSS for the sample was 2.88 (1.24). There was no significant difference between the relapsing remitting type of MS and other types of the MS in the measures total score.

The mean (SD) score of the A-ABC in the first visit was 61.22 (28.79) and 64.21 (26.79) in the second visit. There was no significant difference between the first and second A-ABC total score (P = 0.387). The rest of the mean scores are presented in Table 1.

Table 1
Demographic characteristics of our sample (N = 89)

Characteristic Mean SD Range

Age 37.60 10.1 18–59

BMI 24.61 4.71 14–35

EDSS 2.88 1.24 1–7

BI 89 11.75 60–100

A-BBS 43.03 11.61 10–56

A-DGI 17.25 6.91 1–24

A-ABC: first visit 61.22 28.79 6–100

A-ABC: second visit 64.21 26.79 8–100

Characteristic	Mean	SD	Range
Age	37.60	10.1	18–59
BMI	24.61	4.71	14–35
EDSS	2.88	1.24	1–7
BI	89	11.75	60–100
A-BBS	43.03	11.61	10–56
A-DGI	17.25	6.91	1–24
A-ABC: first visit	61.22	28.79	6–100
A-ABC: second visit	64.21	26.79	8–100

SD = standard deviation. BMI = body mass index. EDSS = Expanded Disability Status Scale. BI = Barthel Index. A-BBS = Arabic Berg Balance Scale. A-DGI = Arabic Dynamic Gait Index. A-ABC = Arabic Activities-specific Balance Confidence scale.

The internal consistency of the A-ABC items using Cronbach’s Alpha (α) was 0.96 with 95% CI of (0.94–0.97). The SEM was 4.07 and the MDC₉₅ of the A-ABC was 11.28 with 95% CI of (10.4 to 12.1). The reliability of the A-ABC was calculated at both total and item scores with 52 patients (58%) who completed the A-ABC twice within one week (Table 2). At the total score, the A-ABC had excellent test-retest reliability (ICC = 0.98; 95% CI = 0.96–0.99). The test-retest reliability of the A-ABC item score reflected high agreement with a range from ICC = 0.90 for “walk in a crowded mall” and “pick up a slipper from the floor” to ICC = 0.99 for “stand on a chair to reach”.

Table 2

Test retest reliability of the Arabic Activities-specific Balance Confidence scale (A-ABC) item and total scores (N = 52)

Activity	Mean (SD)	ICC	95% CI
Walk around the house	79.2 (28.5)	0.90	0.81–0.94
Walk up and down stairs	71.8 (31.8)	0.97	0.94–0.98
Pick up a slipper from the floor	71.8 (35.1)	0.90	0.82–0.94
Reach at eye level	75.9 (34.1)	0.92	0.86–0.96
Reach while standing on your tiptoes	57.6 (38.2)	0.98	0.96–0.99
Stand on a chair to reach	49.4 (40.9)	0.99	0.98–0.99
Sweep the floor	69.4 (39.1)	0.96	0.93–0.98
Walk outside to nearby car	83.5 (27.7)	0.93	0.87–0.96
Get in and out of a car	87.5 (21.8)	0.97	0.94–0.98
Walk across a parking lot	75.3 (34.1)	0.91	0.83–0.95
Walk up and down a ramp	52.9 (35.9)	0.95	0.91–0.97
Walk in a crowded mall	55.8 (35.8)	0.90	0.82–0.94
Walk in a crowd or get bumped	54.5 (38.7)	0.94	0.90–0.97
Ride an escalator holding the rail	76.2 (31.9)	0.94	0.89–0.96
Ride an escalator not holding the rail	52.0 (40.7)	0.95	0.90–0.97
Walk on icy sidewalks	34.7 (40.9)	0.95	0.92–0.97
Total	63.67 (27. 81)	0.98	0.96–0.99

SD = standard deviation. ICC = intraclass confidence interval. CI = confidence interval.

The A-ABC had significant correlations with BBS (r = 0.76, P < 0.05), DGI (r = 0.65, P < 0.05), BI (r = 0.63, P < 0.05), and age of participants (r = –0.37, P < 0.05) (Table 3).

Table 3

Spearman’s correlation coefficient and 95 % confidence interval (CI) for the Arabic Activities-specific Balance Confidence scale (A-ABC) with the Berg Balance Scale (BBS), Dynamic Gait Index (DGI), Barthel Index (BI) and age (N = 89)

The study measures	Spearman correlation with A-ABC and 95% CI	p
A-BBS	0.76 (0.61 to 0.9)	0.001
A-DGI	0.65 (0.43 to 0.91)	0.001
BI	0.63 (0.47 to 0.84)	0.001
Age	–0.37 (–0.56 to –0.16)	0.001

4 Discussion

The main aim of this study was to establish the psychometric properties of the A-ABC in people with MS. Eighty-nine patients with MS were enrolled in this study from multiple sites in Jordan. Participants are considered patients with mild-to-moderate level of disability according to the McDonald criteria of classifying people with MS.

The mean score of the A-ABC in our sample was 61% which may indicate that the majority of patients enrolled in this study are at moderate level of functioning (Myers, Fletcher, Myers, & Sherk, 1998) and at risk of falling (Mak & Pang, 2009). Since the ABC cut-off score for risk of falling was found at scores less 67% which can accurately classify people who fall 84% of the time (Lajoie & Gallagher, 2004). However, these cut-off scores were established for older adults and people with Parkinson’s disease.

In this study, the A-ABC total score had high internal consistency (α= 0.96) which is close to what was reported (α= 0.95) by Swedish people with MS (Nilsagard, Carling, & Forsberg, 2012). However, the same internal consistency result (α= 0.96) was reported in older adults using the original English ABC (Huang & Wang, 2009). High internal consistency was aslo reported in other populations and languages. For example, the internal consistency of the French version of ABC administered to people after stroke was 0.94 (Salbach et al., 2006) while the internal consistency of the Hindi version of ABC administered to older adults was 0.99 (Moiz et al., 2016).

The minimal detectable change (MDC) of the A-ABC in people with MS was established in this study and found to be 11.28 which means that the change in the A-ABC scores should exceed this number in order to reflect a true change in this population. The closest MDC result to our finding was reported in 2011 by people with Parkinson’s disease (MDC = 11.12) (Dal Bello-Haas, Klassen, Sheppard, & Metcalfe, 2011). Only one finding of the MDC (6.9) was less than what we reported which was the Hindi version of the ABC with older adults (Moiz et al., 2016). However, all other MDC findings for the ABC was higher than our MDC such as in people with Parkinson’s disease (MDC = 13) (Steffen & Seney, 2008), individuals with lower limb amputation (MDC = 17.5) (Miller, Deathe, & Speechley, 2003), Italian individuals with MS (MDC = 20) (Cattaneo, Jonsdottir, & Repetti, 2007), and community dwelling older adults (MDC = 21.7) (Powell & Myers, 1995).

Excellent test-retest reliability of the A-ABC total score was reported in the current study (ICC = 0.98) which is higher than the reliability results reported in Italian individuals with MS (ICC = 0.92) (Cattaneo et al., 2007) and comparable to studies conducted in other populations such as in people with Parkinson’s disease (ICC = 0.94) (Steffen & Seney, 2008), people with stroke (ICC = 0.85) (Botner, Miller, & Eng, 2005), and individuals with vestibular disorders (ICC = 0.95) (Alghwiri et al., 2016). Moreover, the A-ABC item score reflected high agreement (ICC≥0.90) which is higher than what was reported in people with vestibular disorders (0.76≥ICC≤0.95) (Alghwiri et al., 2016).

The A-ABC was administered along with performance based balance and mobility measures (BBS and DGI respectively) as well as with activities of daily living self-report measure (BI) in people with MS in order to assess the convergent validity. The correlations of the A-ABC with all outcome measures used reflected positive strong association (r > 0.6). This can be interpreted by the notion that the performance of balance and mobility tasks is linked to high level of balance confidence and less disability. Age of participants was the only demographic factor that was significantly but inversely associated with the A-ABC indicating that the balance confidence of individuals decreases with aging.

Throughout the literature, the ABC convergent validity was explored in relation to the DGI in people with chronic stroke (r = 0.68) (Jonsdottir & Cattaneo, 2007), older adults with balance and vestibular disorders (r = 0.37) (Marchetti, Whitney, Redfern, & Furman, 2011), individuals with peripheral vestibular disorders (r = 0.58) (Legters, Whitney, Porter, & Buczek, 2005), and in Swedish individuals with MS (r = 0.62) (Nilsagard et al., 2012), and in Italian patients with MS (r = 0.54) (Cattaneo, Regola, & Meotti, 2006). The association between the A-ABC and DGI in our sample (r = 0.65) was remarkably higher than what was reported in older adults. However, it is comparable to the correlations reported in individuals with vestibular disorders and persons with MS.

The ABC convergent validity was also evaluated with the BBS in older adults (r = 0.75) (Hatch, Gill-Body, & Portney, 2003), older adults following hip fracture (r = 0.77) (Whitehead, Miller, & Crotty, 2003), people post stroke (r = 0.36) (Botner et al., 2005), individuals with chronic stroke (r = 0.83) (Jonsdottir & Cattaneo, 2007), and Italians with MS (r = 0.48) (Cattaneo et al., 2006). The correlation between the Arabic versions of the ABC and BBS was also examined in people with vestibular disorders (r = 0.54) (Alghwiri et al., 2016) and found comparable to our results in people with MS (r = 0.76).

In our study, there was a significant positive correlation between the A-ABC and BI (r = 0.63, P < 0.05) indicating that better performance of activities of daily living is associated with better balance confidence and less disability in people with MS. The relationship between the A-ABC and BI in people with MS has not been explored before. The modified version of BI was once correlated to the ABC in older adults following hip fracture and found strong (r = 0.67) (Whitehead et al., 2003). Therefore, this finding has an additive value to the relationship between the ABC and BI in the population of MS.

4.1 Limitations

Although this validation study had good sample size, several screening information that could support the results was missing such as baseline falling status. Moreover, other types of MS were not well represented in the current study with the majority of the sample from the relapsing remitting type. Additionally, a gap that was found in the literature is the cutoff scores for the ABC in individuals with MS which needs to be established in future studies.

5 Conclusions

The psychometric properties of the A-ABC were established in people with MS with excellent reliability and validity. Additionally, the MDC of the A-ABC was established in people with MS. Moreover, this study is the first to explore the association between the A-ABC and BI as a disability indicating measure. Therefore, the A-ABC can be utilized with Arabic-speaking individuals with MS to examine their balance confidence and explore risk of falling. This study provided essential information about a well-established balance measure that can be added to other Arabic measures to be used with the population of MS.

Conflict of interest

The authors report no conflict of interest.

Footnotes

Acknowledgments

The authors would like to acknowledge all the participants of the study.

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