Rheumatol Int DOI 10.1007/s00296-013-2942-6
Original Article
Validation of the Quality‑of‑Life Questionnaire of the European Foundation for Osteoporosis (QUALEFFO‑26) in Korean population Jung Sub Lee · Jong Ki Shin · Seung Min Son · Sung Jin An · Sung Shik Kang
Received: 16 October 2013 / Accepted: 30 December 2013 © Springer-Verlag Berlin Heidelberg 2014
Abstract We aimed to evaluate the reliability and validity of the adapted Korean version of the Quality-of-Life Questionnaire of the European Foundation for Osteoporosis (QUALEFFO-26). Translation/retranslation of the English version of QUALEFFO was conducted, and all steps of the cross-cultural adaptation process were performed. The Korean version of the visual analog scale measure of pain, QUALEFFO-26 and the previously validated Short Form-36 (SF-36) were mailed to 162 consecutive patients with osteoporosis. Factor analysis and reliability assessment by kappa statistics of agreement for each item, the intraclass correlation coefficient and Cronbach’s α were conducted. Construct validity was also evaluated by comparing the responses of QUALEFFO-26 with the responses of SF-36 using Pearson’s correlation coefficient. Factor analysis extracted 3 factors. All items had a kappa statistics of agreement greater than 0.6. The QUALEFFO-26 showed good test/retest reliability (QUALEFFO-26: 0.8271). Internal consistency of Cronbach’s α was found to be very good (QUALEFFO-26: 0.873). The Korean version of QUALEFFO-26 showed good significant correlation with SF-36 total score and with single SF-36 domains scores. The adapted Korean version of the QUALEFFO-26 was successfully translated and showed acceptable measurement properties and, as such, is considered suitable for
J. S. Lee (*) · J. K. Shin · S. M. Son · S. J. An Department of Orthopaedic Surgery, School of Medicine, Medical Research Institute, Pusan National University, 1‑10 Ami‑Dong, Seo‑Gu, Busan 602‑739, Republic of Korea e-mail: [email protected] S. S. Kang Department of Orthopaedic Surgery, Medical Research Institute, Yangsan Hospital, Pusan National University, Yangsan, Republic of Korea
outcome assessments in the Korean-speaking patients with osteoporosis. Keywords Osteoporosis · QUALEFFO · Korean version
Introduction Osteoporosis has become a growing public health concern associated with aging of the world’s population. It has been estimated that 30–50 % of women and 15–30 % of men will suffer an osteoporotic fracture in their lifetime [1]. A vertebral fracture is one of the most common osteoporotic fractures and is also a major public health problem affecting millions of people worldwide [2, 3]. Among Korean population, the standardized prevalence for vertebral fractures using the age distribution was 12.6 % in women and 8.8 % in men [4]. Vertebral fractures can be classified as clinical (symptomatic) or morphometric (radiographic) fractures. Both may be associated with significant morbidity in terms of physical and psychological functioning and reduce a subject’s health-related Quality of Life (HRQoL) [5–10], since the sum of physical, social and mental functioning determines important role in clinical studies, and particularly as an outcome measure of clinical trials [11, 12]. Several specific questionnaires assess HRQoL in people with osteoporosis, such as the osteoporosis assessment questionnaire [13], the Osteoporosis Quality-of-Life Questionnaire [14] or the Quality-of-Life Questionnaire in Osteoporosis [15]. The Quality-of-Life questionnaire of the European Foundation for Osteoporosis (QUALEFFO) was developed by the European Foundation for Osteoporosis in 1996 for vertebral deformities. The questionnaire is a well-established disease-specific tool for assessing HRQoL in subjects with
13
clinical and morphometric vertebral fractures [7, 16] and is used to assess the burden of osteoporosis in QoL and the relevant changes during treatment. Originally, the questionnaire included 48 items, but was later condensed to 41 items after validation and included five domains: pain, physical functioning, social functioning, general health perception, and mental functioning. QUALEFFO-41 has good test–retest reliability and internal consistency. Moreover, it has been translated to several languages and has also been reported to be valid and reproducible. The other diseasespecific questionnaires were not extensively used and validated in many different countries. However, the large number of items included in QUALEFFO-41 limited its clinical application. In order to obtain better response rate and be more efficacious in clinical practice, QUALEFFO-31 was developed. This questionnaire has been translated into different languages and has been found to be valid. These kinds of questionnaire must be translated into the respective local languages and must also be culturally adapted. The objectives of this study were to translate into the Korean language a culturally adapted version of the QUALEFFO-31 and to validate this Korean version of the QUALEFFO-31 in Korean patients.
Materials and methods Translation of QUALEFFO The translation and adaptation processes were carried out by following published guidelines for the cross-cultural adaptation of self-report measures [17]. The translation procedure in this study had 3 stages, namely forward translation, back translation and an expert committee discussion. In addition, a pilot study was performed to test whether the prefinal version could be understood correctly by Korean patients with osteoporosis or osteopenia. The final version was achieved by expert committee discussion and tested for its validity and reliability with the Korean version of the Short Form-36 (SF-36) [18]. The forward translation was completed by 2 native Korean translators. The first translator, also the author of this article, is an orthopedic surgeon, and the other is a professional translator, with no medical background, who was not initially informed of the purpose of the translation. The 2 translators’ versions and the original version were compared and discussed by the 2 translators and an orthopedic surgeon, until a synthesis of the translation was reached. The back translation was completed independently by 2 bilingual translators whose native language was English. Both of these translators lacked a medical background
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Rheumatol Int
and were not informed or aware of the prior translation procedures. All versions of the translation, as well as the original, were discussed by the 4 translators and an expert committee comprised of 3 bilingual experts—2 orthopedic surgeons and a Korean translation expert. This committee discussed the translation procedure and results until a consensus was reached on discrepancies. Accordingly, based on the synthetic forward translation, the prefinal version of QUALEFFO-31 was created. Pretest This prefinal version of the QUALEFFO-31 was given to 40 Korean-speaking patients with osteoporosis or osteopenia. Subsequently, these patients were questioned regarding their understanding of the questionnaire items and their responses. These 30 patients included 28 females and 12 males with a mean age of 69.3 (range 49–85). The interviewer was asked to document any problems that occurred during the administration of the questionnaire. In addition, at the end of the interview, each patient was asked to provide comments about the questionnaire and to identify any words that were difficult to understand. The majority of the 40 patients correctly understood the questionnaire. However, among 12 male patients, only 3, 1, 1 and 1 male patients answered question 4 (Can you do the cleaning?), 5 (Can you prepare meals?), 6 (Can you wash the dishes?) and 7 (Can you do your day to day shopping?) of physical function domain, respectively. In addition, 16 patients (40 %) answered question 17 (Can you visit a cinema, theater, etc.?) of physical function domain. The committee decided to omit question 4, 5, 6, 7 and 17 of physical function domain. The final form of the Korean version of the QUALEFFO-26 was determined by the expert committee, with the participation of all translators and a consensus was achieved (see “Appendix”). In the translation process, because of special cultural circumstances and linguistic characteristics of Korean, some modifications of the translations were performed. Because the distance described in the original version in terms of “20Ib, 10 yards and 100 yards” is unfamiliar with Korean people, it was converted to “10 kg, 10 and 100 m.” Sample A total of 162 consecutive patients with osteoporosis were recruited from outpatient orthopedic clinics; 86 patients (53.1 %) with at least one vertebral fracture that had been defined morphometrically and 76 patients (46.9 %) with osteoporosis or osteopenia and no fracture as a control group. The World Health Organization classification for osteoporosis was used to classify the patients [19]. Patients
Rheumatol Int Table 1 The demographic characteristics of the study population
First assessment
Second assessment
Gender (N) Female Male
98 29
80 24
Education (N) Elementary school Middle school High school University
68 33 19 7
58 27 14 5
5 21 17 16 30 38
5 18 16 12 25 28 14.0 (range 9–21)
67/60 34.0 ± 13.0 47.8 ± 19.6
55/49 34.5 ± 12.6 47.3 ± 20.1
44 ± 26
45 ± 25
Profession (N) White collar Blue collar Intermediate level Retired Housewife Unemployed Time period between first and second survey (days) Osteoporosis or osteopenia (N) Fracture/control QUALEFFO-31 (Mean ± SD) SF-36 (Mean ± SD) VAS (Mean ± SD)
who had any important physical disorder were not included in the study. Patients with metabolic bone disease and those with malignancies were excluded. In addition, osteoporotic patients with clinical (symptomatic) vertebral fracture were also excluded. Control subjects were required to have no apparent kyphosis and no morphometric vertebral fracture. The Korean version of the visual analog scale (VAS) measure of pain, QUALEFFO-26 and SF-36 were mailed to 162 consecutive patients (126 females, 36 males) with osteoporosis or osteopenia. First mailing contained a consent form, a description of the study, the Korean versions of VAS measure of pain, QUALEFFO-26 and SF-36, and an addressed and stamped return envelope. One hundred twenty-seven patients (98 females, 29 males) responded to the first set of questionnaires. One hundred four (80 females, 24 males) of the first-time respondents returned their second survey. The average age of the 104 patients was 65.8 years (range 53–83) at the time of survey. The average time between first and second mailings was 2 weeks.
internal consistency. To determine the dimensionality of the items of QUALEFFO-26, factor analysis was also performed. An item loading on each factor ≥0.4 was considered satisfactory. Individual domain score was calculated by summation of the scores of all the questions within that domain followed by linear transformation to a scale of 100, where 0 represented good health and 100 represented poor health. Floor and ceiling effects were assessed by calculating the percentage of subjects with the lowest and highest possible domain scores, respectively. Concurrent and construct validity was evaluated by comparing the responses of QUALEFFO-26 with the results of VAS and responses of SF-36 using Pearson’s correlation coefficient. The distribution of floor and ceiling effects of the Korean QUALEFFO-26 were determined by calculating proportion of individuals obtaining the lowest and highest scores, respectively. All statistical analyses were performed with the SPSS version 16.0.
Measurement
Results
Test–retest reliability was measured by comparing responds to the first and second assessments of QUALEFFO-26. Reliability was assessed using kappa statistics of agreement for each item and the intraclass correlation coefficient (ICC 2,1). Cronbach’s α was used to evaluate
A total of 162 native Korean-speaking patients with osteoporosis or osteopenia were enrolled in this study. One hundred four patients completed the second assessment. Table 1 summarizes the demographic characteristics of the study population.
13
Rheumatol Int
Table 2 Scores of the QUALEFFO-31 and the SF-36 domain Domains QUALEFFO Pain Physical function Mental function QUALEFFO31—total SF-36 Bodily pain Physical function Mental health Mental component score Physical component score
Control (Mean ± SD)
Fracture (Mean ± SD)
P value
33.7 ± 14.2 23.8 ± 15.6 32.7 ± 9.9 28.4 ± 11.9
50.2 ± 13.9 33.1 ± 15.4 30.1 ± 7.4 38.8 ± 11.9
Original Article
Validation of the Quality‑of‑Life Questionnaire of the European Foundation for Osteoporosis (QUALEFFO‑26) in Korean population Jung Sub Lee · Jong Ki Shin · Seung Min Son · Sung Jin An · Sung Shik Kang
Received: 16 October 2013 / Accepted: 30 December 2013 © Springer-Verlag Berlin Heidelberg 2014
Abstract We aimed to evaluate the reliability and validity of the adapted Korean version of the Quality-of-Life Questionnaire of the European Foundation for Osteoporosis (QUALEFFO-26). Translation/retranslation of the English version of QUALEFFO was conducted, and all steps of the cross-cultural adaptation process were performed. The Korean version of the visual analog scale measure of pain, QUALEFFO-26 and the previously validated Short Form-36 (SF-36) were mailed to 162 consecutive patients with osteoporosis. Factor analysis and reliability assessment by kappa statistics of agreement for each item, the intraclass correlation coefficient and Cronbach’s α were conducted. Construct validity was also evaluated by comparing the responses of QUALEFFO-26 with the responses of SF-36 using Pearson’s correlation coefficient. Factor analysis extracted 3 factors. All items had a kappa statistics of agreement greater than 0.6. The QUALEFFO-26 showed good test/retest reliability (QUALEFFO-26: 0.8271). Internal consistency of Cronbach’s α was found to be very good (QUALEFFO-26: 0.873). The Korean version of QUALEFFO-26 showed good significant correlation with SF-36 total score and with single SF-36 domains scores. The adapted Korean version of the QUALEFFO-26 was successfully translated and showed acceptable measurement properties and, as such, is considered suitable for
J. S. Lee (*) · J. K. Shin · S. M. Son · S. J. An Department of Orthopaedic Surgery, School of Medicine, Medical Research Institute, Pusan National University, 1‑10 Ami‑Dong, Seo‑Gu, Busan 602‑739, Republic of Korea e-mail: [email protected] S. S. Kang Department of Orthopaedic Surgery, Medical Research Institute, Yangsan Hospital, Pusan National University, Yangsan, Republic of Korea
outcome assessments in the Korean-speaking patients with osteoporosis. Keywords Osteoporosis · QUALEFFO · Korean version
Introduction Osteoporosis has become a growing public health concern associated with aging of the world’s population. It has been estimated that 30–50 % of women and 15–30 % of men will suffer an osteoporotic fracture in their lifetime [1]. A vertebral fracture is one of the most common osteoporotic fractures and is also a major public health problem affecting millions of people worldwide [2, 3]. Among Korean population, the standardized prevalence for vertebral fractures using the age distribution was 12.6 % in women and 8.8 % in men [4]. Vertebral fractures can be classified as clinical (symptomatic) or morphometric (radiographic) fractures. Both may be associated with significant morbidity in terms of physical and psychological functioning and reduce a subject’s health-related Quality of Life (HRQoL) [5–10], since the sum of physical, social and mental functioning determines important role in clinical studies, and particularly as an outcome measure of clinical trials [11, 12]. Several specific questionnaires assess HRQoL in people with osteoporosis, such as the osteoporosis assessment questionnaire [13], the Osteoporosis Quality-of-Life Questionnaire [14] or the Quality-of-Life Questionnaire in Osteoporosis [15]. The Quality-of-Life questionnaire of the European Foundation for Osteoporosis (QUALEFFO) was developed by the European Foundation for Osteoporosis in 1996 for vertebral deformities. The questionnaire is a well-established disease-specific tool for assessing HRQoL in subjects with
13
clinical and morphometric vertebral fractures [7, 16] and is used to assess the burden of osteoporosis in QoL and the relevant changes during treatment. Originally, the questionnaire included 48 items, but was later condensed to 41 items after validation and included five domains: pain, physical functioning, social functioning, general health perception, and mental functioning. QUALEFFO-41 has good test–retest reliability and internal consistency. Moreover, it has been translated to several languages and has also been reported to be valid and reproducible. The other diseasespecific questionnaires were not extensively used and validated in many different countries. However, the large number of items included in QUALEFFO-41 limited its clinical application. In order to obtain better response rate and be more efficacious in clinical practice, QUALEFFO-31 was developed. This questionnaire has been translated into different languages and has been found to be valid. These kinds of questionnaire must be translated into the respective local languages and must also be culturally adapted. The objectives of this study were to translate into the Korean language a culturally adapted version of the QUALEFFO-31 and to validate this Korean version of the QUALEFFO-31 in Korean patients.
Materials and methods Translation of QUALEFFO The translation and adaptation processes were carried out by following published guidelines for the cross-cultural adaptation of self-report measures [17]. The translation procedure in this study had 3 stages, namely forward translation, back translation and an expert committee discussion. In addition, a pilot study was performed to test whether the prefinal version could be understood correctly by Korean patients with osteoporosis or osteopenia. The final version was achieved by expert committee discussion and tested for its validity and reliability with the Korean version of the Short Form-36 (SF-36) [18]. The forward translation was completed by 2 native Korean translators. The first translator, also the author of this article, is an orthopedic surgeon, and the other is a professional translator, with no medical background, who was not initially informed of the purpose of the translation. The 2 translators’ versions and the original version were compared and discussed by the 2 translators and an orthopedic surgeon, until a synthesis of the translation was reached. The back translation was completed independently by 2 bilingual translators whose native language was English. Both of these translators lacked a medical background
13
Rheumatol Int
and were not informed or aware of the prior translation procedures. All versions of the translation, as well as the original, were discussed by the 4 translators and an expert committee comprised of 3 bilingual experts—2 orthopedic surgeons and a Korean translation expert. This committee discussed the translation procedure and results until a consensus was reached on discrepancies. Accordingly, based on the synthetic forward translation, the prefinal version of QUALEFFO-31 was created. Pretest This prefinal version of the QUALEFFO-31 was given to 40 Korean-speaking patients with osteoporosis or osteopenia. Subsequently, these patients were questioned regarding their understanding of the questionnaire items and their responses. These 30 patients included 28 females and 12 males with a mean age of 69.3 (range 49–85). The interviewer was asked to document any problems that occurred during the administration of the questionnaire. In addition, at the end of the interview, each patient was asked to provide comments about the questionnaire and to identify any words that were difficult to understand. The majority of the 40 patients correctly understood the questionnaire. However, among 12 male patients, only 3, 1, 1 and 1 male patients answered question 4 (Can you do the cleaning?), 5 (Can you prepare meals?), 6 (Can you wash the dishes?) and 7 (Can you do your day to day shopping?) of physical function domain, respectively. In addition, 16 patients (40 %) answered question 17 (Can you visit a cinema, theater, etc.?) of physical function domain. The committee decided to omit question 4, 5, 6, 7 and 17 of physical function domain. The final form of the Korean version of the QUALEFFO-26 was determined by the expert committee, with the participation of all translators and a consensus was achieved (see “Appendix”). In the translation process, because of special cultural circumstances and linguistic characteristics of Korean, some modifications of the translations were performed. Because the distance described in the original version in terms of “20Ib, 10 yards and 100 yards” is unfamiliar with Korean people, it was converted to “10 kg, 10 and 100 m.” Sample A total of 162 consecutive patients with osteoporosis were recruited from outpatient orthopedic clinics; 86 patients (53.1 %) with at least one vertebral fracture that had been defined morphometrically and 76 patients (46.9 %) with osteoporosis or osteopenia and no fracture as a control group. The World Health Organization classification for osteoporosis was used to classify the patients [19]. Patients
Rheumatol Int Table 1 The demographic characteristics of the study population
First assessment
Second assessment
Gender (N) Female Male
98 29
80 24
Education (N) Elementary school Middle school High school University
68 33 19 7
58 27 14 5
5 21 17 16 30 38
5 18 16 12 25 28 14.0 (range 9–21)
67/60 34.0 ± 13.0 47.8 ± 19.6
55/49 34.5 ± 12.6 47.3 ± 20.1
44 ± 26
45 ± 25
Profession (N) White collar Blue collar Intermediate level Retired Housewife Unemployed Time period between first and second survey (days) Osteoporosis or osteopenia (N) Fracture/control QUALEFFO-31 (Mean ± SD) SF-36 (Mean ± SD) VAS (Mean ± SD)
who had any important physical disorder were not included in the study. Patients with metabolic bone disease and those with malignancies were excluded. In addition, osteoporotic patients with clinical (symptomatic) vertebral fracture were also excluded. Control subjects were required to have no apparent kyphosis and no morphometric vertebral fracture. The Korean version of the visual analog scale (VAS) measure of pain, QUALEFFO-26 and SF-36 were mailed to 162 consecutive patients (126 females, 36 males) with osteoporosis or osteopenia. First mailing contained a consent form, a description of the study, the Korean versions of VAS measure of pain, QUALEFFO-26 and SF-36, and an addressed and stamped return envelope. One hundred twenty-seven patients (98 females, 29 males) responded to the first set of questionnaires. One hundred four (80 females, 24 males) of the first-time respondents returned their second survey. The average age of the 104 patients was 65.8 years (range 53–83) at the time of survey. The average time between first and second mailings was 2 weeks.
internal consistency. To determine the dimensionality of the items of QUALEFFO-26, factor analysis was also performed. An item loading on each factor ≥0.4 was considered satisfactory. Individual domain score was calculated by summation of the scores of all the questions within that domain followed by linear transformation to a scale of 100, where 0 represented good health and 100 represented poor health. Floor and ceiling effects were assessed by calculating the percentage of subjects with the lowest and highest possible domain scores, respectively. Concurrent and construct validity was evaluated by comparing the responses of QUALEFFO-26 with the results of VAS and responses of SF-36 using Pearson’s correlation coefficient. The distribution of floor and ceiling effects of the Korean QUALEFFO-26 were determined by calculating proportion of individuals obtaining the lowest and highest scores, respectively. All statistical analyses were performed with the SPSS version 16.0.
Measurement
Results
Test–retest reliability was measured by comparing responds to the first and second assessments of QUALEFFO-26. Reliability was assessed using kappa statistics of agreement for each item and the intraclass correlation coefficient (ICC 2,1). Cronbach’s α was used to evaluate
A total of 162 native Korean-speaking patients with osteoporosis or osteopenia were enrolled in this study. One hundred four patients completed the second assessment. Table 1 summarizes the demographic characteristics of the study population.
13
Rheumatol Int
Table 2 Scores of the QUALEFFO-31 and the SF-36 domain Domains QUALEFFO Pain Physical function Mental function QUALEFFO31—total SF-36 Bodily pain Physical function Mental health Mental component score Physical component score
Control (Mean ± SD)
Fracture (Mean ± SD)
P value
33.7 ± 14.2 23.8 ± 15.6 32.7 ± 9.9 28.4 ± 11.9
50.2 ± 13.9 33.1 ± 15.4 30.1 ± 7.4 38.8 ± 11.9
