ABSTRACT
Objective:
To translate and validate the Adult Strabismus Quality of Life Questionnaire into Brazilian Portuguese.
Methods:
A cross-sectional study for linguistic and cross-cultural validation of the Adult Strabismus Quality of Life Questionnaire in order to assess the quality of life in patients with strabismus. We have followed previous published guidelines on translation process to ensure the equivalence between the original and translated versions. The final version was applied in a pilot study to evaluate concordance and its reliability and reproducibility as a tool to be used in future studies.
Results:
The translation and counter translation processes of the Adult Strabismus Quality of Life Questionnaire were conducted according to preestablished protocols. The analysis of the results obtained in the test–retest application of the questionnaire in a sample of 30 participants revealed a correlation coefficient of 0.67, which was deemed satisfactory for the validation process of this tool.
Conclusion:
The Adult Strabismus Quality of Life Questionnaire was translated and validated according to preestablished protocols. The referred questionnaire has been used in studies worldwide, so this process will enable its application to better understand the impact of strabismus in patients’ quality of life in the Brazilian population.
Keywords:
Strabismus; Amblyopia; Quality of life; Surveys and questionnaires; Cross-cultural validation
RESUMO
Objetivo:
Traduzir e validar o questionário Adult Strabismus Quality of Life Questionnaire (AS-20) para o português brasileiro.
Métodos:
Estudo transversal para validação linguística e transcultural do questionário Adult Strabismus Quality of Life Questionnaire (AS-20) para avaliação da qualidade de vida em pacientes com estrabismo. Foram seguidas as diretrizes já publicadas sobre o processo de tradução, para garantir a equivalência entre as versões original e traduzida. A versão final foi aplicada em um estudo-piloto para avaliar a concordância e sua confiabilidade e reprodutibilidade, como ferramenta a ser utilizada em estudos futuros.
Resultados:
Os processos de tradução e contratradução do questionário Adult Strabismus Quality of Life Questionnaire (AS-20) foram realizados de acordo com protocolos preestabelecidos. A análise dos resultados obtidos na aplicação teste-reteste do questionário em uma amostra de 30 participantes revelou coeficiente de correlação de 0,67, que foi considerado satisfatório para o processo de validação desse instrumento.
Conclusão:
O questionário Adult Strabismus Quality of Life Questionnaire (AS-20) foi traduzido e validado de acordo com protocolos preestabelecidos. O referido questionário vem sendo utilizado em estudos ao redor do mundo e, portanto, esse processo possibilitará sua aplicação para melhor compreensão do impacto do estrabismo na qualidade de vida dos pacientes da população brasileira.
Descritores:
Estrabismo; Ambliopia; Qualidade de vida; Inquéritos e questionários; Validação transcultural
INTRODUCTION
Strabismus affects people of all ages, but it is most common in children. There is a negative impact on health-related quality of life because of the change in appearance. (11 Buffenn AN. The impact of strabismus on psychosocial heath and quality of life: a systematic review. Surv Ophthalmol. 2021;66(6):1051-64.) A growing number of studies have reported that patients with strabismus have a higher proclivity for mental illness and a negative impact on their self-image, relationships with others, and work.(22 Sah SP, Sharma IP, Chaudhry M, Saikia M. Health-related quality of life (HRQoL) in young adults with strabismus in India. J Clin Diagn Res. 2017;11(2):NC01-NC4.)
A cross-sectional study conducted in 11 cities in the center-west of São Paulo, Brazil, found that the prevalence of strabismus was approximately 1.4%, correlating with global data.(33 Shimauti AT, Pesci Lde T, Sousa RL, Padovani CR, Schellini SA. [Strabismus: detection in a population-based sample and associated demographic factors]. Arq Bras Oftalmol. 2012;75(2):92-6. Portuguese.)
The surgical treatment of strabismus aims to align the visual axes to achieve image fusion and binocularity restoration. In addition, it also intends to correct abnormal head position, expand the visual field, eliminate diplopia (double vision), improve eye motility, and promote psychomotor development.(44 Olitsky SE, Sudesh S, Graziano A, Hamblen J, Brooks SE, Shaha SH. The negative psychosocial impact of strabismus in adults. J AAPOS. 1999;3(4):209-11.) Although often overlooked, the benefits of improved self-esteem and psychological health should be considered in surgical decision-making.(55 Rosenbaum AL. Adult strabismus surgery: the rehabilitation of a disability. J AAPOS. 1999;3(4):193.)
When compared to other interventions, strabismus surgery is effective, long-lasting, and has few risks. It is cost-effective, especially in children, because of their long life expectancy. In adults with long-term strabismus, the incidence of permanent postoperative diplopia is only 1%.(66 Liebermann L, Hatt SR, Leske DA, Holmes JM. Improvement in specific function-related quality-of-life concerns after strabismus surgery in nondiplopic adults. J AAPOS. 2014;18(2):105-9.,77 Martinez-Thompson JM, Diehl NN, Holmes JM, Mohney BG. Incidence, types, and lifetime risk of adult-onset strabismus. Ophthalmology. 2014;121(4):877-82.)
The quantitative assessment of the quality of life of patients with strabismus is an important contribution to the clinical examination because it allows for a better understanding of the condition and an accurate assessment of treatment effectiveness.(88 Hatt SR, Leske DA, Bradley EA, Cole SR, Holmes JM. Development of a quality-of-life questionnaire for adults with strabismus. Ophthalmology. 2009;116(1):139-44.e5.)
Currently, no strabismus-specific questionnaire is available in Brazilian Portuguese. The Adult Strabismus Quality of Life Questionnaire (AS-20) (22 Sah SP, Sharma IP, Chaudhry M, Saikia M. Health-related quality of life (HRQoL) in young adults with strabismus in India. J Clin Diagn Res. 2017;11(2):NC01-NC4.,99 Fossum P, Le Meur G, Couret C, Pechereau A, Hode F, Albert F, et al. [Validation of the French version of the health-related quality of life questionnaire for adult strabismus (AS-20)]. J Fr Ophtalmol. 2017;40(9):738-43.) is a standardized English questionnaire used to assess health-related quality of life and functional vision in adults with strabismus. The AS-20 questionnaire was developed based on patient interviews in which expressed feelings and phrases were collected. Subsequently, each statement by the patient was converted into a question, generating a 181-item questionnaire. Each question was refined, and items that could differ based on socioeconomic, cultural, or educational status were removed, yielding the AS-20 questionnaire, which consisted of 20 questions divided into a psychosocial scale and a functional scale.(88 Hatt SR, Leske DA, Bradley EA, Cole SR, Holmes JM. Development of a quality-of-life questionnaire for adults with strabismus. Ophthalmology. 2009;116(1):139-44.e5.,1010 Hatt SR, Leske DA, Liebermann L, Holmes JM. Incorporating health-related quality of life into the assessment of outcome following strabismus surgery. Am J Ophthalmol. 2016;164:1-5.)
With its validation in Portuguese, another valuable resource for assessing the impact of strabismus on an individual's daily life will be available, thereby making it possible to measure the results of the treatment in clinical practice and research, corroborating the definition of clinical treatments, and identifying patients in need of psychosocial support, occupational therapy, and rehabilitation. (88 Hatt SR, Leske DA, Bradley EA, Cole SR, Holmes JM. Development of a quality-of-life questionnaire for adults with strabismus. Ophthalmology. 2009;116(1):139-44.e5.,1111 Hatt SR, Leske DA, Bradley EA, Cole SR, Holmes JM. Comparison of quality-of-life instruments in adults with strabismus. Am J Ophthalmol. 2009;148(4):558-62.)
The aim of this study was to translate and validate the Portuguese version of this questionnaire. The AS-20 questionnaire is self-administered, and each of the 20 questions about feelings and difficulties in patients with strabismus is designed to be answered on a five-point Likert-type scale (never corresponds to 100; rarely, to 75; sometimes, to 50; often, to 25; and always, to zero). The median total score can range from zero (worst quality of life) to 100 (best quality of life).
METHODS
The present study was approved by the Universidade Estadual de Campinas (Unicamp) Research Ethics Committee (number CAAE: 18913819.8.0000.5404, protocol number 3.571.455) and was performed in accordance with the Declaration of Helsinki.
The original English version of the AS-20 questionnaire was translated into Portuguese using a three-phase process first proposed by Beaton et al. and Gjersing et al., as described in figure 1. (1212 Beaton DE, Bombardier C, Guillemin F, Ferraz MB. Guidelines for the process of cross-cultural adaptation of self-report measures. Spine (Phila Pa 1976). 2000;25(24):3186-91.,1313 Gjersing L, Caplehorn JR, Clausen T. Cross-cultural adaptation of research instruments: language, setting, time and statistical considerations. BMC Med Res Methodol. 2010;10:13.)
The study design according to the guideline proposed for the translation and validation processes.
The following is the original English version of the AS-20 questionnaire:
The following is the original Portuguese version of the AS-20 questionnaire:
First, two independent translators and native Portuguese speakers translated and cross-culturally adapted the English version into Portuguese, followed by an evaluation of the translated version by a panel of two ophthalmologists (one general ophthalmologist and one strabismus specialist), two residents, and a medical student.
The Portuguese version was then translated into English by two independent native speakers, and the same interdisciplinary panel evaluated and compared it to the original English version. Based on the suggestions of the interdisciplinary committee, the translation was revised by the researchers to establish the final version.
The final version of the questionnaire was administered to a group of 30 volunteers over the age of 18 years old to verify the agreement of the answers and the validation process. Participants signed an Informed Consent Form. To assess the reproducibility of the questionnaire, a second test was conducted with the same volunteers (Table 1).
Qualitative, descriptive analysis of test and retest answers for each of the 20 questions administered to the 30 participants
The AS-20 questionnaire is self-administered, and each of the 20 questions about feelings and difficulties in the individual with strabismus is designed to be answered on a 5-point Likert-type scale (never corresponded to 100; rarely, to 75; sometimes, to 50; often, to 25, and always, to 0). The median total score can range from zero (worst quality of life) to 100 (best quality of life). Figure 1 displays the study design according to the guidelines proposed for the translation and validation processes.
Statistical methodology
To describe the answers of the questionnaire in relation to the Likert scale categories, frequency tables with absolute values (n) and percentages (%) were created. To describe the answers according to the value corresponding to each category as well as to describe the total results according to the dimension and general result, descriptive analyses of mean, standard deviation, median, 1st quartile, 3rd quartile, minimum, maximum, and sample size were conducted. (Tables 2,3,4)
Values of the quantitative descriptive analysis of the scores pertaining to questions one to ten (psychic scale)
Values of the quantitative descriptive analysis of the scores pertaining to questions 11 to 20 (functional scale)
Values of the quantitative descriptive analysis of the scores pertaining to questions 1 to 20 (psychic scale and functional scale)
The intraclass correlation coefficient was used to assess the agreement between test and retest results. For the questions in which the test results had no variance in their answers, it was not possible to calculate any measure of agreement (Table 5).
Results of the intraclass correlation coefficient between test and retest answers for the psychic scale (answers 1 to 10), functional scale (answers 11 to 20), and both scales (answers 1 to 20)
For statistical analysis, the following computer programs were used: The Statistical Analysis System (SAS) for Windows, version 9.4 (SAS Institute Inc., 2002-2008, Cary, NC, USA and R Core Team, 2020) and R: A language and environment for statistical computing. (R Foundation for Statistical Computing, Vienna, Austria. URL: https://www.r-project.org). For the interpretation of the intraclass correlation coefficient, the following values were used according to Koo et al.(1414 Koo TK, Li MY. A Guideline of selecting and reporting intraclass correlation coefficients for reliability research. J Chiropr Med. 2016;15(2):155-63.): <0.5, poor correlation; 0.5 to 0.75, moderate; 0.75 to 0.90, good; and >0.9, excellent.
RESULTS
The Portuguese version of the AS-20 questionnaire was administered twice to a group of 30 volunteers over the age of 18 years old. Because the questionnaire consisted of simple and direct questions, reproducibility was good and there were no difficulties during the translation and adaptation phases. Similarly, no disagreements arose during the other stages of the process. Correlation coefficient values were consistently satisfactory and statistically significant for all 20 items.
Table 1 shows the qualitative descriptive analysis of the test and retest answers for each of the 20 questions administered to the 30 participants. For each question, the absolute values of the number (n) and the percentage of participants who responded (%) are presented along with their assigned scores for each category of the Likert scale.
According to Koo et al., in the interpretation of the intraclass correlation coefficient for the psychic scale (questions one to ten), the agreement index between the test and retest was 0.67, revealing a moderate level of agreement. For the functional scale (answers ranging from 11 to 20), the agreement index between the test and retest was 0.77, indicating a good level of agreement. In the total answers (psychic and functional scales together, answers ranging from 1 to 20), the agreement index between test and retest was 0.67, revealing a moderate level of agreement.(1414 Koo TK, Li MY. A Guideline of selecting and reporting intraclass correlation coefficients for reliability research. J Chiropr Med. 2016;15(2):155-63.)
DISCUSSION
Strabismus surgery is often classified as an aesthetic procedure in patients who do not have binocular vision potential or have diplopia; however, this term is considered incorrect because it is not just a beautifying procedure but rather an instrument to restore normalcy as a result of pathology.(1515 Beauchamp CL, Beauchamp GR, Stager DR Sr, Brown MM, Brown GC, Felius J. The cost utility of strabismus surgery in adults. J AAPOS. 2006;10(5):394-9.)
Strabismus is one of the most debilitating ophthalmological conditions. (1616 Bez Y, Coskun E, Erol K, Cingu AK, Eren Z, Topcuoglu V, et al. Adult strabismus and social phobia: a case-controlled study. J AAPOS. 2009;13(3):249-52.) The impact on the quality of life of patients with strabismus is similar to that of macular degeneration and mild stroke but greater than that of diabetic retinopathy. However, unlike these conditions, strabismus can be surgically corrected, thereby substantially improving the quality of life of these patients. (1717 Kushner BJ. The benefits, risks, and efficacy of strabismus surgery in adults. Optom Vis Sci. 2014;91(5):e102-9.)
Questionnaires are useful tools in health-related research, and they are increasingly being used to analyze the quality of life related to a specific disease, quantify symptoms, assess the natural course of the disease, and determine the effects of treatment strategies.(11 Buffenn AN. The impact of strabismus on psychosocial heath and quality of life: a systematic review. Surv Ophthalmol. 2021;66(6):1051-64.)
The use of standardized and validated research instruments allows for comparisons of results from different studies at the national and international levels, but the use of validated questionnaires does not guarantee their legitimacy for use in different languages and cultures. Therefore, language translation, along with cross-cultural adaptation of validated questionnaires, becomes necessary to achieve the equivalence of these questionnaires to be used in different languages, countries, and cultures.(1111 Hatt SR, Leske DA, Bradley EA, Cole SR, Holmes JM. Comparison of quality-of-life instruments in adults with strabismus. Am J Ophthalmol. 2009;148(4):558-62.,1818 Santo RM, Ribeiro-Ferreira F, Alves MR, Epstein J, Novaes P. Enhancing the cross-cultural adaptation and validation process: linguistic and psychometric testing of the Brazilian-Portuguese version of a self-report measure for dry eye. J Clin Epidemiol. 2015;68(4):370-8., 1919 Wang ZH, Bian W, Ren H, Frey R, Tang LF, Wang XY. Development and application of the Chinese version of the adult strabismus quality of life questionnaire (AS-20): a cross-sectional study. Health Qual Life Outcomes. 2013;11:180.)
Quality of life questionnaires can quantify the psychosocial consequences of strabismus in an individual's life. The assessment of quality of life is an important aspect to consider in the management of patients with strabismus in order to define surgical procedures and indications because it allows for a better understanding of this condition and access to effective treatment. Adults with strabismus appear to have a lower quality of life, but questionnaires are not used to define procedures in clinical practice. (2020 Leske DA, Hatt SR, Holmes JM. Test-retest reliability of health-related quality-of-life questionnaires in adults with strabismus. Am J Ophthalmol. 2010;149(4):672-6.) The use of questionnaires allows for the evaluation of treatment outcomes in clinical practice and clinical trials. (2020 Leske DA, Hatt SR, Holmes JM. Test-retest reliability of health-related quality-of-life questionnaires in adults with strabismus. Am J Ophthalmol. 2010;149(4):672-6.)
Although there have been few studies evaluating the AS-20 questionnaire in children, it can be used to assess the quality of life in children with strabismus through parental perception. When compared to the VFQ-25, the AS-20 questionnaire was more sensitive in detecting functional and psychosocial changes. (1111 Hatt SR, Leske DA, Bradley EA, Cole SR, Holmes JM. Comparison of quality-of-life instruments in adults with strabismus. Am J Ophthalmol. 2009;148(4):558-62.)
The translation and validation of the AS-20 questionnaire in this study will provide a new tool for assessing the impact of strabismus surgery on different age groups and disease subtypes as well as help in the standardization of a resource for clinical research in the field.
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Institution: Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, SP, Brazil.
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Financial support: The authors received no financial support for this work.
REFERENCES
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1Buffenn AN. The impact of strabismus on psychosocial heath and quality of life: a systematic review. Surv Ophthalmol. 2021;66(6):1051-64.
-
2Sah SP, Sharma IP, Chaudhry M, Saikia M. Health-related quality of life (HRQoL) in young adults with strabismus in India. J Clin Diagn Res. 2017;11(2):NC01-NC4.
-
3Shimauti AT, Pesci Lde T, Sousa RL, Padovani CR, Schellini SA. [Strabismus: detection in a population-based sample and associated demographic factors]. Arq Bras Oftalmol. 2012;75(2):92-6. Portuguese.
-
4Olitsky SE, Sudesh S, Graziano A, Hamblen J, Brooks SE, Shaha SH. The negative psychosocial impact of strabismus in adults. J AAPOS. 1999;3(4):209-11.
-
5Rosenbaum AL. Adult strabismus surgery: the rehabilitation of a disability. J AAPOS. 1999;3(4):193.
-
6Liebermann L, Hatt SR, Leske DA, Holmes JM. Improvement in specific function-related quality-of-life concerns after strabismus surgery in nondiplopic adults. J AAPOS. 2014;18(2):105-9.
-
7Martinez-Thompson JM, Diehl NN, Holmes JM, Mohney BG. Incidence, types, and lifetime risk of adult-onset strabismus. Ophthalmology. 2014;121(4):877-82.
-
8Hatt SR, Leske DA, Bradley EA, Cole SR, Holmes JM. Development of a quality-of-life questionnaire for adults with strabismus. Ophthalmology. 2009;116(1):139-44.e5.
-
9Fossum P, Le Meur G, Couret C, Pechereau A, Hode F, Albert F, et al. [Validation of the French version of the health-related quality of life questionnaire for adult strabismus (AS-20)]. J Fr Ophtalmol. 2017;40(9):738-43.
-
10Hatt SR, Leske DA, Liebermann L, Holmes JM. Incorporating health-related quality of life into the assessment of outcome following strabismus surgery. Am J Ophthalmol. 2016;164:1-5.
-
11Hatt SR, Leske DA, Bradley EA, Cole SR, Holmes JM. Comparison of quality-of-life instruments in adults with strabismus. Am J Ophthalmol. 2009;148(4):558-62.
-
12Beaton DE, Bombardier C, Guillemin F, Ferraz MB. Guidelines for the process of cross-cultural adaptation of self-report measures. Spine (Phila Pa 1976). 2000;25(24):3186-91.
-
13Gjersing L, Caplehorn JR, Clausen T. Cross-cultural adaptation of research instruments: language, setting, time and statistical considerations. BMC Med Res Methodol. 2010;10:13.
-
14Koo TK, Li MY. A Guideline of selecting and reporting intraclass correlation coefficients for reliability research. J Chiropr Med. 2016;15(2):155-63.
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15Beauchamp CL, Beauchamp GR, Stager DR Sr, Brown MM, Brown GC, Felius J. The cost utility of strabismus surgery in adults. J AAPOS. 2006;10(5):394-9.
-
16Bez Y, Coskun E, Erol K, Cingu AK, Eren Z, Topcuoglu V, et al. Adult strabismus and social phobia: a case-controlled study. J AAPOS. 2009;13(3):249-52.
-
17Kushner BJ. The benefits, risks, and efficacy of strabismus surgery in adults. Optom Vis Sci. 2014;91(5):e102-9.
-
18Santo RM, Ribeiro-Ferreira F, Alves MR, Epstein J, Novaes P. Enhancing the cross-cultural adaptation and validation process: linguistic and psychometric testing of the Brazilian-Portuguese version of a self-report measure for dry eye. J Clin Epidemiol. 2015;68(4):370-8.
-
19Wang ZH, Bian W, Ren H, Frey R, Tang LF, Wang XY. Development and application of the Chinese version of the adult strabismus quality of life questionnaire (AS-20): a cross-sectional study. Health Qual Life Outcomes. 2013;11:180.
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20Leske DA, Hatt SR, Holmes JM. Test-retest reliability of health-related quality-of-life questionnaires in adults with strabismus. Am J Ophthalmol. 2010;149(4):672-6.
Publication Dates
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Publication in this collection
03 Mar 2023 -
Date of issue
2023
History
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Received
27 July 2022 -
Accepted
15 Aug 2022