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ISSN : 1225-8962(Print)
ISSN : 2287-982X(Online)
Physical Therapy Korea Vol.22 No.4 pp.51-61
DOI : https://doi.org/10.12674/ptk.2015.22.4.051

Content Validity of a Korean-Translated Version of a Fullerton Advanced Balance Scale: A Pilot Study

Gyoung-mo Kim
Dept. of Physical Therapy, Division of Health Science, Baekseok University
Corresponding author: Gyoung-mo Kim kgm6240@naver.com
October 1, 2015 October 2, 2015 November 2, 2015

Abstract

The purpose of this study were to translate the Fullerton Advanced Balance (FAB) scale into Korean and to verify the content validity by utilizing a back-translation method with a view to assessing balance function and the risk of falling in a clinical research setting. This research was conducted in six steps. First, three Korean physical therapists translated the FAB scale into Korean. Second, two bilingual professors of physical therapy and a physical therapist evaluated translation conformity of Korean-translated FAB scale. In the third and fourth steps, twelve physical therapists evaluated the degree of translation comprehension, and a translator back-translated the Korean FAB scale into the original language. Fifth, a bilingual professor of physical therapy and two native speakers evaluated the technical and conceptual equivalence between the original and translation versions. In this process, inappropriate translated items were revised using recommended substitute words or sentences, and all items were evaluated on the basis of three points or more on a rating scale in terms of translation comprehension, and the technical and conceptual equivalence of the back-translation. In the sixth and last step, the translation verification committee completed the final Korean version. The above process indicated that the content validity of the Korean-translated FAB scale was established by means of systematic translation methods, and it can therefore be used to assess balance function and the risk of falls in a clinical research setting.


초록


    Baekseok University

    Introduction

    Falls are the leading cause of functional disability, and mortality in the elderly people over 65 years (Fortinsky et al, 2008). The occurrence of falls causes physical injuries such as a fractures, joint dislocation, traumatic brain damage, as well as decreased independent activities and quality of life. Also, fear of falling consistently correlates to psychosocial conditions such as an anxiety and depression (Legters, 2002; Nevitt et al, 1989). Hospitalization rate due to falling was 1,566 and mortality rate was 36 per 100,000 of the Korea population in the elderly people over 65 years (Korea Centers for Disease Control and Prevention, 2009).

    Many factors contribute to an increased fall risk in older adults, including impairments in balance, decreased muscular strength, and impaired vision due to aging. Hazard environments such as rough and slippery terrain in the home and community are also risk factors (American Geriatric Society, 2001; Baker et al, 2005). However, falls could be prevented if the risk factors were identified and if early assessment and appropriate intervention were implemented (Hernandez and Rose, 2008). Of the factors listed above, balance is one of the most important ways to predict fall prevention measures (Fortinsky et al, 2008). Balance assessment methods are divided into single-item component (e.q., range of motion, muscular strength, vision) and multidimensional function that include related balance factors (Weerdesteyn et al, 2008). The single- item component method is easy to measure but has the limitation that it only evaluate one factor relating to balance function. On the other hand, multidimensional function method is useful because it evaluate a variety of factors related to balance, and it also expresses balance function as a total score (Kim, 2013).

    Several assessment tools have been used to evaluate the balance function, including Timed Up and Go Test (Newton, 1997), Functional Reach Test (Duncan et al, 1990), Berg Balance Scale (BBS) (Berg et al, 1992), Dynamic Gait Index (Hall et al, 2004) and Fullerton Advance Balance (FAB) Scale (Rose et al, 2006). Because these assessment tools were developed in other countries, the process of translation, adaptation and cross-cultural validation of the tools for use in other countries, cultures, and languages requires the adoption of the most well-established, comprehensive and rigorous methodological approaches (Sousa and Rojjanasrirat, 2011; Sperber, 2004). Therefore, such tools should ideally be translated into Korea language and undergo a valid translation process so that they can be used in Korea. However, in many instances, literal translation is difficult to achieve, particularly when the linguistic structure of the target language is distinctly different from that of the source language. If the original language of assessment tool was translated inadequate or incorrect words, or if idiomatic expression from other cultures were literally translated, the meaning of the original will not be expressed accurately and the results of assessment will be compromised (Yoo, 2003). In addition, if the assessment tool is used in researches without having undergone rigorous procedures of translation and verification, the reliability and validity of the research itself is likely to be undermined (Custers et al, 2000; Lim et al, 2007).

    In general, when the instrument is translated, there should be both technical equivalence and conceptual equivalence. Technical equivalence refers to equivalence in terms of grammar and syntax, while conceptual equivalence refers to the absence of concept differences between the original and target versions of instrument (Yoo, 2003). Various procedures have been proposed to ensure translation accuracy, and back-translation is generally the method most recommended. The back-translation method involves translation of the target language version of a document back to the original language by a translator who is not familiar with the instrument being translated; the back-translated items are then compared to the original items so that any discrepancies can be identified. This method permits the detection of errors in the translation, such as the omission of phrases or words that may change the meaning of the item, as well as the identification of words or phrases that cannot be accurately or literally translated (Bulliger et al, 1998; Sperber, 2004).

    Although the BBS is mainly used to assess the risk of falling in older adults, it has several limitations. For example, it is not suitable for predicting a fall in a group of higher functioning older adults due to its propensity to display ceiling effects. Moreover, BBS items are strongly associated with reduced lower extremity function, but they do not include items that evaluate impairments in multiple sensory systems such as the vestibular system and vision, which have been found to contribute to balance and a heightened fall risk in independently functioning older adults (Boulgarides et al, 2003; Brauser et al, 2000; Rose et al, 2006).

    The FAB scale is a performance-based measure that was developed by Rose et al (2006) in order to identify the subtle changes in balance and to assess the multiple dimensions of balance. In addition to evaluating the multiple dimensions of balance such as both static and dynamic environments, sensory reception and integration, and anticipatory and reactive postural control, the FAB scale includes items that are specifically designed to change the balance abilities of independently functioning older adults (Rose et al, 2006).

    Several studies have been conducted to assess balance function and the risk of falls using the BBS, and the reliability and validity of the BBS have therefore been verified in Korea (Jung et al, 2006; Lee et al, 2006; Park, 2008). However, as yet, no study has been carried out using the FAB scale in Korea, and little research has been conducted to verify this assessment tools using rigorous translation procedures (Lee et al, 2011; Lim et al, 2007). The purpose of the present study was to translate the FAB scale into Korean and verify its content validity by means of a back-translation method with a view to assessing balance function and the risk of falls in a clinical research setting.

    Methods

    Research subjects and procedures

    This research subjects and procedures for this study were selected based on past researches (Lee et al, 2011; Lim et al, 2007; Neuman et al, 2004). Essentially, the research was conducted using the following procedures; translation of the FAB scale into Korean; translation conformity and comprehension; assessment of the technical and conceptual equivalence of back translation; and completion of Korean version of the FAB scale (Table 1).

    Instrument

    The FAB scale is a multi-item balance assessment test designed specifically to measure balance in higher-functioning active older adults (Klein et al, 2011; Rose et al, 2006). The scale consisted of 10 items describing balance impairment in the performance of static and dynamic balance activities in different sensory environments. Each item is graded on a four-point Likert scale (range 0~4), with 0 indicating that the person is unable to perform 4 indicating that an activity is possible to perform. The total score ranges from 0 to 40, and is used as a predictor variable in studies. A scores 25 or lower on the FAB scale indicates a high risk of falls and a need for immediate intervention. The FAB scale has shown high test-retest level (r=.96), as well as intra-reliability (r=.92~1.00) and inter- reliability (r=.91~.95). Also, it has indicated good correlation with the BBS (r=.75, p<.001) (Hernandez and Rose, 2008; Horak et al, 2009; Klein et al, 2011; Rose et al, 2006).

    Translation procedures

    The FAB scale was first translated into Korean language by three physical therapists who had experienced assessment and treatment using a balance assessment tool. The conformity of the translated FAB scale was then verified by two bilingual (English and Korean) physical therapy professors and one physical therapist who were not familiar with the FAB scale. Conformity was evaluated using 5-point ordinal scale consisting of the levels 1 (very bad), 2 (bad), 3 (moderate), 4 (good), 5 (very good). Items evaluated with a rating of 2 (bad) or less by two or more of the three translation conformity reviewers were modified through the recommendation of substitute words or sentences until a rating of 3 or more was achieved. After the first revision, the degree of translation comprehension of the FAB scale was verified by twelve physical therapists who had experienced treating patients with balance impairments. The comprehension degree was evaluated using a 5-point ordinal scale consisting of the levels 1 (not quite understood), 2 (not understood), 3 (moderately well understood), 4 (understood), 5 (well understood). Items evaluated with a rating of 2 (not understood) or less by two or more of the twelve reviewers were modified through the recommendation of a substitute words or sentences by the translation verification committee. A translation expert was then commissioned to carry out back translation, and the technical equivalence and conceptual equivalence of the back translation were evaluated between the original and translation versions by a USA professor in possession of a master’s degree, in addition to two native speakers. Equivalence was evaluated using a 5-point ordinal scale consisting of levels 1 (not at all similar), 2 (not similar), 3 (moderately similar), 4 (similar), 5 (very similar). A rating of 2 (not similar) or less by one or more of the three reviewers resulted in the item being modified to a level of 3 (similar) or more. Finally, a translation verification committee consisting of three bilingual physical therapy professors and two physical therapists completed Korean version of the FAB scale after all verification processes had been carried out (Appendix 1).

    Results

    Conformity of translation

    As a result of translation conformity, each item that scored a rating of 2 (bad) or less was revised through the recommendation of a substitute words or sentences until a level of 3 or more was achieved (Table 2).

    Comprehension of translation

    As a result of the degree of translation comprehension, all items received a rating of more than 3 (moderate). The lowest item was “step up and over” (3.63) and the highest item was “stand on one leg” (4.36) (Table 3).

    Technical equivalence and conceptual equivalence of back-translation

    In technical equivalence and conceptual equivalence, all items were evaluated as 3 (moderate) or more. The “step up and over” and “stand on foam, eyes closed” items were evaluated as 3 (moderate) in technical equivalence by two of the three reviewer, but their conceptual equivalence was evaluated as 4 (similar) or more (Table 4).

    Discussion

    The purpose of the present study was to translate the FAB scale into Korean and verify its content validity by means of a back-translation method so that it could be used as a balanced assessment tool in clinical research setting. The aim of systematic translation is to maintain the validity of the questionnaire itself, and to maintain similarities between sentence structure and the conceptual identity the source text, thereby maintaining the source text’s structure and meaning (Chae et al, 2008). The greatest difficulty that researchers experience in a study using an assessment tool from a different culture is appropriately translating the tool from a different language into one’s home language by reducing the differences in languages and cultures (Candell and Hulin, 1986). There are four methods of keeping the equivalence between an assessment tool in the source language and in the target language: back translation, two-language translation, translation verification committee approach, and the pretest procedure (Brislin, 1970). In this study, back translation and the translation verification committee approaches were used, and following the procedure presented by Bullinger et al (1998) a translation, a back translation, a comparison of differences between the source and back-translation versions, a committee review, and a qualitative analysis were performed.

    A frequent problem in the translation process is the lack of words in the home language with the same meaning as the source words (Brislin et al, 1970). Therefore, effort should be made to use words that have the most-similar meaning to the source words. The best method for solving this problem in the translation process is to translate the meaning instead of using the grammatical word (Sechrest and Fay, 1972). In this study, the equivalence of the communication of meaning was set as the criterion of translation in the initial translation and conformity of translation. During the translation of the FAB scale into Korean, it was difficult to find words that accurately reflected the meaning of certain source words and phrases. For example, there is no Korean word corresponding to ‘foam’ as written in the FAB source, so the loanword ‘sponge’ was used, and it was decided to translate the English word ‘supervision’ as the meaning of ‘watch closely’ instead of its typical meaning as ‘supervision’ in Korean translation.

    In systematic translation research, the qualification of the researchers participating in the translation and the conformity process are also important. To avoid literal translations, the translator must be proficient in both languages and knowledgeable about the cultures of both countries as well as in the principles of test-development and the writing of items (Jones et al, 2001; Son, 2003; Yoo, 2003). Because verification of translation comprehension requires basic knowledge of the specialist area, 12 physical therapists participated in this study to verify the understanding of the items, and the translator showed an average (3) level of understanding for every item. Furthermore, biases due to regional and cultural differences of the individuals participating in the translation should be reduced. Hence, due to the complexity of the translation process, a modification process through the translation verification committee consisting of various experts is required (Jones et al, 2001; Son, 2003; Yoo, 2003). In this study, a translation verification committee consisting of two bilingual physical therapy professors and two physical therapists made the final decision after gathering neutral opinions from different perspectives, together with the translator.

    When an assessment tool is translated, the equivalence of the translation cannot be ensured just by translating the source text into the home language (Brislin, 1970; Sechrest and Fay, 1972) Therefore, it is essential to raise the validity by using back translation in cross-cultural research (Jones et al, 2001; McDermott and Palchanes, 1992). In this study, to enhance the validity of the translation, technical and conceptual equivalence of back translation were evaluated by one bilingual physical therapy professor and two native speakers of English. As a result of the back translation, there were words and phrases that were different from the source text, but all 10 of the items received at least 3 points (average) in the similarity of sentence structures and the communication of meaning. Therefore, there were no items that required revision. After confirming the conformity and comprehension of translation for every item, the Korean version of the FAB scale was finally completed.

    A limitation of this study was that the results only present the translated version of the FAB scale. The back translation method is very useful for the initial work that evaluates the quality of a translation, but it is insufficient for establishing the cross-cultural and linguistic equivalence (Hulin et al, 1982). Therefore, the need for statistical methods is raised (Son, 2003). The combined use of the back translation and the reliability and validity study for establishing the equivalence of tests has been reported to be the best method (Kim and Lim, 2003). In future studies, the statistical reliability and validity should be researched by directly applying the translated FAB scale to patients. Furthermore, linguistic validity does not mean that the translation has the specifics of the original psychological measurements (Ku et al, 2005). Therefore, the degree of test equivalence between the original FAB scale and the translated version needs to be analyzed through the Rasch analysis, which was developed on the basis of the item response theory.

    Conclusion

    In this study, the FAB scale was translated through the back translation method, and the conformity of the Korean translation was verified in order to establish its validity for use in Korea. The FAB scale was translated into Korean through a systematic translation process. Furthermore, the goodness-of-fit of the translation was verified by a translation verification committee consisting of three bilingual physical therapy professors and two physical therapists, and the translation was revised accordingly. In the back-translation process, the similarities of sentence structures and of the communication of meaning were both tested. After the final Korean version was completed, its content validity was established so that it could be applied in Korea.

    Figure

    Table

    Research subjects and procedures

    aFullerton advance balance.

    Conformity of Korean translation

    Comprehension of translation (N=12)

    amean±standard deviation.

    Technical equivalence and conceptual equivalence of back-translation (N=3)

    양발 모으고 눈 감고 서 있기

    물건을 향하여 손 뻗기

    제자리에서 회전하기

    발판을 딛고 올라서 넘어가기

    한 발로 서있기

    눈 감고 스펀지에 서기

    두 발로 멀리뛰기

    머리 회전하면서 걷기

    반응적 자세 조절

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