FormalPara Key Summary Points

The Mini-BESTest has been adapted to the Persian language but has not been evaluated for reliability and validity.

This study evaluated the inter-rater and discriminative validity of the Persian Mini-BESTest in balance evaluation of patients with stroke.

The Persian Mini-BESTest is a reliable and valid tool for balance evaluation of patients with stroke.

Persian-speaking clinicians can use the Persian Mini-BESTest in the clinic and research to assess balance in patients with stroke.

Introduction

Annually about 84.16–103.23 per 100,000 Iranians experience a stroke [1]. Most stroke patients will suffer from balance disorder and postural instability because of muscle weakness and sensory problems [2, 3]. Change in balance reflexes [4], sensory organization disorders [5] and alterations in attention requirements during postural tasks [6] all play roles in this balance deficit. Balance disorder can be a major risk factor for falling [7], which can lead to fall-related injuries [8]. A comprehensive balance assessment can guide treatment for a suitable approach that can reduce the balance deficits and fall risk [9].

Several tools can be used for balance assessment. The Four Square Step Test (FSST) [10], Timed Up and Go (TUG) [11], Dynamic Gait Index (DGI) [12] and Berg Balance Scale (BBS) [13] are useful tests for balance assessment, but they have limitations [14]. TUG and FSST are single-task tests that are useful for screening; however, they cannot comprehensively assess the balance systems. The scoring system is not clear for the DGI. The BBS does not assess dynamic balance or have a ceiling effect [14].

The Balance Evaluation Systems Test (BESTest) is a new tool that assesses different balance systems including biomechanical constraints, stability limits/verticality, anticipatory postural adjustments, postural responses, sensory orientation and gait stability. The BESTest can detect the system responsible for the balance impairment and can subsequently direct treatment [15]. BESTest's reliability, validity, sensitivity and specificity have been demonstrated in patients with sub-acute stroke [16]. BESTest takes 20–35 min to administer [15], which reduces its clinical feasibility.

The Mini-BESTest is the shorter version of the BESTest, which takes 10–15 min to administer. Using Factor and Rasch analyses, 14 of the 36 items of the BESTest, which mostly represent dynamic balance, have been selected for the Mini-BESTest [17]. The Mini-BESTest is valid and reliable for assessing patients with chronic stroke and is more accurate than the BBS for identifying fallers post-stroke [18].

Although the original English version of the Mini-BESTest is a valid and reliable tool in assessing patients with balance disorders, the reliability and validity of the Persian version has not been evaluated in patients with stroke. The aim of the present study is to evaluate the validity and reliability of the Persian Mini-BESTest in patients with stroke. We hypothesized that the Persian version of the Mini-BESTest is a reliable and valid tool for balance evaluation of patients with stroke.

Methods

Design

This cross-sectional study was approved by the Research Council of the Neuromusculoskeletal Research Center and the Ethics Committee of Iran University of Medical Sciences (ethics code: IR.IUMS.REC1396.311411). The procedure was completely explained to each patient, and written informed consent for participation in the study was obtained. This study was performed in accordance with the Helsinki Declaration of 1964 and its later amendments.

Participants

A group of patients with chronic stroke participated in the study. Each patient was matched with a healthy adult in terms of age and gender. Our inclusion criteria for the patient group were: (1) diagnosis of stoke, (2) ability to live independently in the community, (3) ability to speak Persian, (4) ability to follow a three-step command, (5) ability to walk 6 m without aid, (6) no history of pathologic vertigo, (7) no history of pathologic faint, (8) no history of other vascular, musculoskeletal or neurologic problems that affect the balance and (9) no use of drugs affecting the balance in the past 48 h. Patients were excluded if they did not complete the test or did not agree to participate in the study.

Our inclusion criteria for the neurologic healthy group were: (1) living independently in the community, (2) ability to speak Persian, (3) ability to perform the commands, (4) ability to walk 6 m without aid, (5) giving consent, no history of pathologic faint or vertigo, (6) no use of drugs that affect balance in the past 48 h and (7) no history of medical conditions such as neurologic or musculoskeletal disorders that affect balance.

Procedure

The study took place in the neurologic physiotherapy clinic of the rehabilitation faculty of Tehran University of Medical Sciences. The environment was quiet and separated from other patients. Before performing the test, the demographic characteristics of each patient were recorded.

Reliability

Two physical therapists and a medical student participated in the study. Prior to the study initiation, raters participated in an educational session on the Mini-BESTest held by the first author. The session included a review of the study procedure, watching the BESTest training video provided by Prof. Horak, reading the testing instructions and practicing.

For the inter-rater reliability, two trained physical therapists scored the test for each patient in a session. For assessing each patient, one rater administered the test. After the patients had performed each item, the raters independently scored the performance on the test item according to the Mini-BESTest criteria. Inter-rater reliability was determined for the total scores and section scores. The raters were blinded to their ratings, and no discussion of the scores assigned was allowed.

Validity

To evaluate whether the Persian Mini-BESTest can distinguish between healthy adults and stroke patients (discriminative validity), each patient was matched with a healthy adult according to age and gender. A medical student administered the test and rated the performance of all the healthy subjects. For assessing the discriminative validity, the total Mini-BESTest scores of patients and healthy subjects were compared. The total Mini-BESTest scores assigned for patients in the inter-rater reliability phase of the study were used, and scores provided by one of the raters were randomly selected for comparison.

Outcome Measures

The Mini-BESTest is a clinical balance test consisting of 4 sections and 14 items (Table 1). Each item is scored from 0 (worst performance) to 2 (best performance). The total score is 28.

Table 1 Sections and items of the Mini-BESTest
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Sample Size and Data Analysis

According to the guidelines we included 30 patients with stroke and 30 neurologically healthy subjects for reliability and discriminative validity assessment [19]. The percentage of male and females among patients was calculated. Mean and standard deviation (SD) for demographic and outcome variables were calculated. Kolmogorov-Smirnov test was used to determine normality. Pearson’s correlation coefficients were used to assess the inter-rater reliability. Correlation values < 0.4 were interpreted as poor, between 0.4 and 0.75 as moderate and > 0.75 as excellent [20]. To assess the discriminative validity, the independent T test or the Mann-Whitney U test was used depending on the normality of the data. SPSS software (version 16 for Windows, SPSS Inc., Chicago, Il) was used for analyses.

Results

Of the 30 patients, 17 were male (56.7%) and 13 female (43.3%). Fourteen patients had right hemiplegia (46.7%) and 16 had left hemiplegia (53.3%). Other demographic data are shown in the Table 2.

Table 2 Demographic characteristics of patients
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Reliability

Mean and SD of the Persian Mini-BESTest total score, section scores and correlation coefficients between two raters are shown in Table 3. The Persian Mini-BESTest total scores had excellent inter-rater reliability for the total score (rp = 0.98, P < 0.001) (Fig. 1) and section scores (rp = 0.91–1.0).

Table 3 Mean and standard deviation (SD) of total and section scores for the Persian Mini-BESTest rated by two raters and correlation between their scores
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Fig. 1
figure 1

Scatter plot for the Persian Mini-BESTest total scores assigned by two raters (rp = 0.98, P < 0.001)

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Discriminative Validity

Mann-Whitney U test showed significant differences in the Persian Min-BESTest total score between patients with stroke (mean 19.4 and SD 5.4) and healthy subjects (mean 24.8 and SD 2.3), P < 0.001.

Discussion

This study investigated the inter-rater reliability and validity of the Persian Min-BESTest in patients with stroke and demonstrated that the Persian version of the Mini-BESTest had excellent inter-rater reliability and discriminative validity in distinguishing between patients with stroke and healthy subjects.

Our results for inter-rater reliability are in line with those of Tsang et al. [18] as they found that the original version of the Mini-BESTEST had excellent inter-rater reliability for evaluating patients with chronic stroke (ICC 0.93–0.99). Another study found that the Mini-BESTest had excellent inter-rater reliability in a group of patients with balance disorders (ICC 0.98) [21]. This excellent inter-rater reliability found with the Persian Mini-BESTest in patients with chronic stroke is comparable to those demonstrated for the BESTest (ICC 0.99) [16] and BBS (ICC 0.97–0.98) [13]. A review on the psychometric properties of the Mini-BESTest found excellent inter-rater reliability (ICC between 0.86–0.99) [22]. Using a stopwatch for objective scoring of 5 out of 14 items and clear instructions provided for both patients and raters might play a role in the high reliability of the Persian Mini-BESTest. Before the study, both of our raters had no experience with using the Mini-BESTest. The excellent inter-rater reliability of the Persian Mini-BESTest indicates that the two raters' lack of experience with the Persian MinBESTest did not affect the level of reliability, and the Persian Mini-BESTest was reliable even with novice raters.

We found that all sections of the Persian Mini-BESTest had excellent inter-rater reliability in testing patients with stroke. A previous study with patients with stroke reported adequate to excellent inter-rater reliability for all the test items [18]. In this study, the highest agreement (100%) between the two raters was observed for the sensory orientation section. The stationary exercises only being included in the sensory orientation section and criteria for scoring items being based on the time patients needed to complete a task could be the reasons why the two raters had perfect agreement. This finding is in agreement with a previous report in patients with Parkinson’s disease that also found the highest agreement for the sensory orientation [23].

We demonstrated a significant difference between patients with stroke and healthy subjects in the total score, confirming the discriminative validity of the Persian Mini-BESTest. This finding is in line with previous reports in patients with stroke [18] and different patient groups and healthy older adults [22]. Our findings indicate the ability of the Persian version of the Mini-BESTest to discriminate between stroke patients with balance disorder and healthy subjects.

This study had limitations. First, the test was administered by one of the raters while the second rater concurrently observed and scored the balance performance. This might reduce the generalizability of the findings to the clinical context. Second, we only examined stroke patients; thus, the results of the present study may not be generalizable to other diseases causing balance disorders. Further studies investigating the reliability and validity of the Persian version of the Mini-BESTest in patients with different balance disorder etiologies are suggested. Third, we only evaluated the inter-rater reliability and discriminative validity of the Persian Mini-BESTest; future studies are needed to evaluate the other aspects of reliability and validity. Fourth, responsiveness to evaluating the sensitivity of the Persian Mini-BESTest to detect changes over time after an intervention and to determine minimally clinically important change was not investigated in this study. Fifth, the sensitivity and specificity of the Persian version of the Mini-BESTest in predicting future falls were not investigated in our study.

Conclusion

This study demonstrated that the Persian version of the Mini-BESTest has excellent reliability and validity in evaluating balance deficits. The Persian version of the Mini-BESTest, a useful and quick clinical test, can be used by clinicians for assessing balance deficits of patients with stroke in Persian-speaking countries.