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Keywords:

  • Cross-cultural adaptation;
  • SLEQOL;
  • Chinese;
  • Quality of life;
  • Systemic lupus erythematosus

Abstract

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. Acknowledgements
  9. REFERENCES
  10. APPENDIX A
  11. APPENDIX B
  12. Supporting Information

Objective

We have previously validated the English version of the Systemic Lupus Erythematosus Quality of Life Questionnaire (SLEQOL) in our patients with lupus. Many of our Chinese patients are not fluent in English and therefore a Chinese version (SLEQOL-C) has been adapted for their use.

Methods

Two independent translators translated the SLEQOL into Chinese. A consensus version was derived from both sets of translations. Back translation of this version was performed by another 2 independent translators who had neither been involved in the forward translation nor encountered the SLEQOL. The final version, SLEQOL-C, was finalized after rectifying the discrepancies revealed by the back translation. Linguistic validity was tested in open interviews with bilingual patients with lupus. The SLEQOL-C and SLEQOL were administered to patients to determine whether they displayed differential item functioning (DIF).

Results

In general, most of the items in English could be expressed in Chinese precisely, although a few instructions had to be altered slightly to make them more idiomatic. The forward and back translations of the SLEQOL were accomplished without major difficulties. A total of 638 patients were interviewed (62.8% with the SLEQOL and 37.2% with the SLEQOL-C). Using DIF analysis, there was no detectable test bias due to language use after controlling for repeated observations, age, sex, and ethnicity.

Conclusion

The SLEQOL-C has semantic, idiomatic, and conceptual equivalence to the SLEQOL. The rigorous process of cross-cultural translation provides some measure of quality in the content validity.


INTRODUCTION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. Acknowledgements
  9. REFERENCES
  10. APPENDIX A
  11. APPENDIX B
  12. Supporting Information

Advances in medical care have greatly reduced mortality in systemic lupus erythematosus (SLE) (1). Consequently, improving the quality of life (QOL) of patients with SLE has become one of the major goals of modern therapy. To evaluate the success of treatment, a reliable instrument that measures QOL is needed. Over the last decade, health status instruments, such as QOL measures that encompass the physical, psychological, and emotional dimensions, have been used to assess the impact of SLE from the patient's perspective. The Medical Outcomes Study 36-item Short Form Health Survey (SF-36) has been shown to be valid and reliable in measuring QOL in patients with SLE (2, 3), although it has recently been found to be insensitive to change (4). Recently, our group developed an SLE-specific QOL scale in English (SLEQOL) and demonstrated its validity, reliability, and responsiveness to change (5, 6).

Although some of the general health measures, such as the SF-36 (2, 3), the Health Assessment Questionnaire (7), and the abbreviated form of the World Health Organization Quality of Life instrument (8), have been translated and validated for Chinese-speaking patients, a validated SLE-specific QOL scale is not available in the Chinese language to date. We believe that the availability of such an instrument is important for a few reasons: one-quarter of the world's population is Chinese, there is a higher incidence and severity of SLE in the Chinese compared with other ethnic groups (9, 10), and 75.6% of the population in Singapore is Chinese, a significant number of whom are not fluent in English, particularly those of the older generation. We describe herein the steps we took to translate and develop the Chinese version of the SLEQOL (SLEQOL-C) using established methodology (11, 12) to derive a reliable and valid QOL instrument. To prove that the translated SLEQOL-C is of the same construct as the SLEQOL, we demonstrated equivalence between the 2 versions. Equivalence means that the probability of a patient affirming a question in English is the same as the probability of the patient answering the question in the same way in another language or medium, given that the trait or construct is measured at the same level on both occasions.

PATIENTS AND METHODS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. Acknowledgements
  9. REFERENCES
  10. APPENDIX A
  11. APPENDIX B
  12. Supporting Information

Patients.

All patients fulfilled the 1997 revised American College of Rheumatology classification criteria for SLE (13). Patients were prospectively recruited from our outpatient rheumatology clinic and the hospital wards in a single institution as part of an ongoing longitudinal cohort study of SLE that was started in 2002. In this study, demographic data including age at onset (defined as the initial manifestation[s] clearly attributable to SLE), age at diagnosis, age at protocol entry, socioeconomic status, smoking history, clinical manifestations at disease onset, and cumulative clinical, hematologic, and immunologic manifestations during the course of followup were recorded into a database. At each study visit, the following information was collected using a standard protocol: current and past disease manifestations, disease activity (using the revised Systemic Lupus Activity Measure [SLAM-R] &lsqbr;14&rsqbr;), disease damage (using the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index [SDI] &lsqbr;15&rsqbr;), full blood count, erythrocyte sedimentation rate, complement C3 and C4 levels, anti–double-stranded DNA titers, and therapy. Patients enrolled within 3 years of disease duration were prospectively followed up at 4-month intervals, whereas those with disease duration >3 years were seen at yearly intervals for the study visits. The patients had to be fluent in either English or Chinese, as appropriate. This study was approved by our institutional research ethics board and informed consent was obtained according to the Declaration of Helsinki.

Preparation.

Although more than 200 dialects are spoken by the Chinese people, there is a uniform written language (16). There are 2 forms of written Chinese: the original (traditional Chinese), which is more complex, and the modern, which is simplified. The difference lies in the number of strokes required to constitute each character. Traditional Chinese is used in Taiwan and Hong Kong while the simplified form is used in mainland China and Singapore. We used the simplified form for this project. If this questionnaire is to be used in populations that are more familiar with the traditional form, the characters may be substituted directly with no change in meaning (although this has not been proven in practice) (17).

Although Chinese sentences may be constructed from right to left or left to right, we chose the left to right format so that the Chinese questionnaire approximated the English version. The translation was performed in accordance with the recent guidelines for cross-cultural adaptation (12).

Forward translation from English to Chinese and reconciliation.

Two independent forward translations of the SLEQOL from English to Chinese were commissioned. One translator, a trained research nurse and therefore an informed translator (HJH), aimed for equivalency from a clinical and measurement perspective. The other translator (Huey Fang Tay), a schoolteacher, was the uninformed or naive translator. A consensus version was derived from both sets of translations after discussions between both translators and one of the investigators, a rheumatologist (KOK).

Back translation from Chinese to English.

To ensure consistency of translation and to detect gross inconsistencies or conceptual errors, the consensus version of the SLEQOL-C was independently back translated to English by naive translators Han Wei Lee and Gett Lim Chang, who were blinded to the original English version. Comparison of the original SLEQOL and the back-translated version enabled the ready identification of linguistically or conceptually mistranslated items.

Harmonization.

An expert committee (comprising the 2 rheumatologists KOK and KPL and all 4 translators) was created to prepare the prefinal version of the SLEQOL-C for field testing after all the translations were reviewed and discrepancies resolved. Decisions were made by this committee to ensure semantic, idiomatic, and conceptual equivalence between the source and target versions. In accordance with recommendations for the design of QOL questionnaires, we ensured that the language proficiency required for understanding the SLEQOL-C was no higher than that of a 12-year-old.

Cognitive debriefing.

We used an open-interview approach to assess the linguistic validity of the Chinese SLEQOL. In the cross-cultural rendering of QOL instruments, the individual items should be translated accurately, precisely, and idiomatically. In addition, the questions should not place the respondent in an uncomfortable position, leading to missing responses and reduced patient cooperation. We wanted to find out from our respondents if any of the items were unsuitable in this sense, so that the translated questionnaire could be modified. Seven bilingual patients with SLE were asked to complete the SLEQOL, first in Chinese then in English. They were then asked to assess the difficulty in understanding the items in Chinese (using a Likert scale of 1–7, least to most difficult) and the embarrassment in answering the questions (using a Likert scale of 1–7, least to most embarrassing). One of the authors (KPL) interviewed these patients.

Equivalence.

There are multiple meanings of equivalence when applied to QOL instruments. Writers have listed and defined at least 6: conceptual equivalence, item equivalence, semantic equivalence, operational equivalence, measurement equivalence, and functional equivalence (18, 19).

Conceptual, item, and semantic equivalences are qualitative, and the careful translation and rechecking by the expert committee ensured that these were retained. To confirm that the SLEQOL and SLEQOL-C were equivalent, differential item functioning (DIF) analysis was utilized. For a specific item written in different languages, substantial DIF should not be apparent when the item truly measures the same trait in the different languages (QOL in our case). An item is therefore said to exhibit DIF when the distribution of responses obtained from 2 large groups of patients with differing abilities (not necessarily matched between groups) is substantially different in the 2 language versions. The item then cannot be regarded as equivalent in the 2 languages and responses obtained from different language versions must not be analyzed together. We used the DIFDetect computer program (Stata Corporation, College Station, TX) (20), which is based on the ordinal logistic regression technique suggested by Zumbo (21), to perform DIF analysis. DIF can also be analyzed with contingency tables and the Mantel-Haenszel test (22), but with a large number of respondents (generally accepted as >200), Zumbo's method is preferable and has the added advantage of the ability to distinguish uniform and nonuniform DIF (23).

Statistical significance was defined as a P value less than 0.01 to adjust for multiple hypotheses testing. In keeping with good statistical methods, the test value (P value) should be accompanied by some measure of the magnitude of the difference. This is necessary because small sample sizes can hide interesting differences whereas large sample sizes may show statistically significant findings in which the difference is quite small and meaningless in a practical sense (21). The magnitude of DIF was measured by the change in the maximal R2 (ΔR2) between models with different language versions. Substantial DIF was defined as a change in the estimates of ≥0.03, a rather conservative effect size compared with Zumbo's suggested value of ≥0.130 (21). Items that were both statistically significant and had substantial DIF were reexamined regarding the validity of cross-cultural adaptation. The full analysis of the psychometric properties of the SLEQOL-C needed to demonstrate measurement equivalence and functional equivalence will be presented in another report.

RESULTS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. Acknowledgements
  9. REFERENCES
  10. APPENDIX A
  11. APPENDIX B
  12. Supporting Information

Characteristics of patients.

There were 638 patients with SLE in the study. Of these, 237 (37.2%) completed the SLEQOL-C and the rest completed the SLEQOL. The characteristics of patients are shown in Table 1. In general, patients in the SLEQOL-C group were older, had longer disease duration, and lower socioeconomic status compared with those in the SLEQOL group. However, disease activity and damage, as measured by the SLAM-R and SDI, were comparable between the 2 groups.

Table 1. Demographics, disease activity, accumulated damage, and disease duration of the patients with systemic lupus erythematosus who participated in the study*
CharacteristicsSLEQOLSLEQOL-CP
  • *

    Values are the percentage unless otherwise indicated. One Singapore dollar was equivalent to US$0.65 at the time of writing. SLEQOL = Systemic Lupus Erythematosus Quality of Life Questionnaire; SLEQOL-C = Chinese version of the SLEQOL; NS = not significant; SLAM-R = revised Systemic Lupus Activity Measure; SDI = Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index.

Age, mean ± SD years37.86 ± 11.9147.63 ± 11.91< 0.001
Female sex91.089.9NS
Disease duration, mean ± SD months124.79 ± 4.33143.32 ± 6.820.02
Educational level  < 0.001
 Primary or no formal education10.544.7 
 Secondary45.944.7 
 Tertiary43.610.6 
Occupation  < 0.001
 Professionals11.51.3 
 Clerical/service workers33.222.8 
 Blue collar workers12.225.7 
 Homemakers21.040.5 
 Students/national servicemen11.50.4 
 Retired/unemployed10.79.3 
Monthly household income, $Singapore  < 0.001
 <$1,00016.031.2 
 $1,000–$2,99950.455.3 
 ≥$3,00033.713.5 
SLAM-R, median (interquartile range)3 (1–5)3 (1–5)NS
SDI, median (interquartile range)0 (0–1)0 (0–1)NS

English to Chinese forward translations and their reconciliation.

In general, most items in English could be precisely expressed in Chinese because they concerned common activities and emotions and were not abstract ideas. However, the instructions had to be slightly modified to make them more idiomatic. For example, the adjectives in the scale could not be translated literally because the shades of meaning are very close, especially at the extremes (7 and 6, and 1 and 0). However, the translators managed to maintain a sense of gradation. In Chinese, the time descriptor is usually placed at the beginning of the sentence; therefore, in those instances the sentence was constructed as linguistically appropriate for the Chinese language. After resolving the minor discrepancies through discussion among the committee, a final translated version of SLEQOL-C was produced.

Chinese to English back translation.

With the availability of back translations for comparison, the minor differences in translation in terms of syntax and lexicon were identified and resolved by the committee. Because the SLEQOL was designed based on common daily experiences, there was hardly any difficulty in translating most items.

Harmonization results.

Although the arrangement of the sentences might be different in both language versions to allow the smooth flow of instructions in the SLEQOL-C, the meaning of every sentence/paragraph was preserved. As mentioned, the time descriptor is usually placed at the beginning of the sentence in Chinese, notably in the stem questions mainly. For example, a question in the SLEQOL such as “How difficult has each of these activities been in the last week as a result of your SLE?” becomes “In the past week, because of SLE, what is the difficulty level of these activities?” in the SLEQOL-C.

Some difficulty was encountered in the translation of the adverb moderate from English to Chinese, because this term is not commonly used in Chinese. In general, an adjective without an adverb is assumed to be of moderate degree in Chinese. After considering the common usage of the language, we omitted the term moderate. As a result, the backward translation also did not include this adverb in the scale. Although the adjectives used in the scale were slightly different from those in the original SLEQOL, especially in regard to the frequency of events, the progression of the scale was preserved in the Chinese version, i.e., grade 6 is clearly worse than grade 5. Another lexical problem involved the word sore, because it can mean discomfort, pain, tenderness, ache, irritating, or stinging. After considering the context of the questions, the word tenderness was selected and translated to “pain when touched” in Chinese. The item sex also connotes different meanings in regard to sexual life. Because it referred to sexual activity in the original SLEQOL, it was translated as sexual activity or sexual intercourse.

After discussion within the committee, there were no further changes in the wording of the translated questionnaire. The final translated SLEQOL-C (Appendix B, available at the Arthritis Care & Research Web site at http://www.interscience.wiley.com/jpages/0004-3591:1/suppmat/index.html) was thought to be simple and easily understood by patients with primary school reading ability.

Results of cognitive debriefing.

The mean ± SD time taken to complete the SLEQOL-C was 3.74 ± 1.35 minutes, which was significantly longer than that taken to complete the English version (2.88 ± 0.89 minutes; P < 0.01). There was no difficulty or embarrassment in answering any of the questions. All patients responded to questions on whether the questionnaire was too difficult or embarrassing to answer with “neither difficult to understand nor embarrassing to answer” except for one respondent, who assessed the difficulty of understanding question 5 (“bathing and drying yourself”) as 3. This respondent's reason for the assessment was that the complete sentence was redundant, because the act of bathing also implies the subsequent act of drying oneself. All the patients thought that the terms were equivalent in Chinese and in English, except for minor differences in item 14, where “go out under the sun” was translated as “exposed to the sun,” and item 28, where “self-consciousness” was rendered into the more specific “self-consciousness about appearance.”

Equivalence findings.

As shown in Table 2, none of the items in the SLEQOL demonstrated statistically significant and substantial DIF across the 2 language versions, suggesting that the SLEQOL has been successfully adapted to the Chinese language.

Table 2. Differential item functioning (DIF) between the items in each language*
Items in SLEQOL-CNonuniform DIFUniform DIF
PChange in estimatesP
  • *

    There was no substantial DIF (change in estimates >0.03) between the items in each language. See Table 1 for definitions.

Walking0.7230.0250.044
Shopping0.0480.0140.166
Taps on and off0.9150.0140.157
Marketing1.0000.0210.072
Bathing0.9170.0090.277
Kilometers0.0320.0270.013
Work performance0.0910.0070.015
Interference with career0.1220.0040.002
Missing work0.0950.0000.948
Relationship with friends0.0010.0070.216
Taking part in sports0.2540.002< 0.001
Sexual relation0.0260.0040.400
Social activities< 0.0010.0050.167
Unable to be expose under the sun0.2960.0030.510
Making less money0.0170.0030.479
Poor memory0.4750.0050.275
Loss of appetite0.9390.0060.254
Fatigue0.2830.0010.722
Poor concentration0.0780.0040.285
Itchy skin0.8360.0040.251
Sore mouth0.9800.0040.559
Sore skin0.7480.0040.517
Join pain0.6860.0080.045
Fear of needles0.9690.0080.449
Dietary restrictions0.3350.0070.159
Inconvenience of daily medication0.2820.010< 0.001
Inconvenience of frequent clinic visit0.9010.0110.006
Self-consciousness0.9410.0050.006
Feeling low0.9210.0030.377
Depression0.9740.0020.589
Anxiety0.7720.0080.114
Wish other people did not know0.8020.0030.687
Being made fun by friends0.8130.0120.087
Low self-esteem0.5510.0010.908
Embarrassment< 0.0010.0240.013
Financial burden0.5590.0060.179
Medicines do not work0.5030.0050.146
Side effects0.4440.0020.221
Bad news from doctors0.3950.0060.039
Consuming more alcohol0.6210.0250.003

DISCUSSION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. Acknowledgements
  9. REFERENCES
  10. APPENDIX A
  11. APPENDIX B
  12. Supporting Information

The first guideline for cross-cultural adaptation of QOL instruments was published more than a decade ago (11). The process has become widely used and numerous variations and complexities have emerged. Herdman et al (24) advocated a nuanced approach to cross-cultural adaptation. The standard approach as defined by Beaton et al (12) is a necessary, but not sufficient, condition for cross-cultural validity. Attention should also be given to the linguistic features of both versions in order to preserve the original construct and avoid any pitfalls in translation. In addition to careful adherence to the translation process, examining for DIF satisfies the requirements of conceptual, item, and semantic equivalences as defined by Herdman and colleagues (24). If DIF is demonstrated, it is possible to modify the culprit items and field test the instrument again until DIF is eliminated. This proved to be unnecessary in our study.

In modern written Chinese, phrases instead of single words are used to elaborate an idea, even though on occasion a single word may suffice. In a way, this provides an advantage, because words with divergent meanings are then made more specific. This difference in the sentence structure of questions in both languages could explain why the questionnaire in English could be completed in a shorter amount of time.

Despite the difference in the basic characteristics of the cohorts in the study as shown in Table 1, the absence of DIF (Table 2) suggests that there are no systematic differences in the meaning of the individual items in the 2 languages. Indeed, Zumbo's method (21) is based on item response function and performs DIF analysis independently of the characteristics of the respondents.

Principles of good practice for the translation and cultural adaptation process of QOL instruments have recently been published (25). The steps in the process defined and recommended by the report are preparation, forward translation, reconciliation, back translation, back translation review, harmonization, cognitive debriefing, review of cognitive debriefing results and finalization, proofreading, and final report. Although we began our work before the report was published, we have been compliant with the general principles. Beyond the recommendations, we have demonstrated that DIF did not exist in the responses from a large number of English- and Chinese-speaking patients with SLE.

In summary, we have translated the SLEQOL into Chinese in accordance with recent guidelines and without major difficulties. The SLEQOL-C does not exhibit statistically significant DIF compared with the SLEQOL, suggesting that the translations were accurate and precise. Definitive validation of the SLEQOL-C awaits detailed study of its psychometric properties.

AUTHOR CONTRIBUTIONS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. Acknowledgements
  9. REFERENCES
  10. APPENDIX A
  11. APPENDIX B
  12. Supporting Information

Dr. Kong had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Study design. Kong, Howe, Leong.

Acquisition of data. Kong, Ho, Howe, Thong, Lian, Chng, Leong, and members of the Tan Tock Seng Hospital Systemic Lupus Erythematosus Study Group.

Analysis and interpretation of data. Kong, Leong.

Manuscript preparation. Kong, Howe, Thong, Lian, Chng, Leong.

Statistical analysis. Kong.

Acknowledgements

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. Acknowledgements
  9. REFERENCES
  10. APPENDIX A
  11. APPENDIX B
  12. Supporting Information

We thank Gett Lim Chang, Han Wei Lee, and Huey Fang Tay for their translation work in this cross-cultural rendering of the SLEQOL.

REFERENCES

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. Acknowledgements
  9. REFERENCES
  10. APPENDIX A
  11. APPENDIX B
  12. Supporting Information
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APPENDIX A

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. Acknowledgements
  9. REFERENCES
  10. APPENDIX A
  11. APPENDIX B
  12. Supporting Information

THE TAN TOCK SENG HOSPITAL SYSTEMIC LUPUS ERYTHEMATOSUS STUDY GROUP

Ee Tzun Koh, FRCPE, Tang Ching Lau, MRCP, Yew Kuang Cheng, MRCP, Weng Giap Law, MRCP, Wern Hui Yong, MRCP, and Eleen Yun Yin Chong, MRCP.

Supporting Information

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. Acknowledgements
  9. REFERENCES
  10. APPENDIX A
  11. APPENDIX B
  12. Supporting Information
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