Translating health status questionnaires and evaluating their quality: the IQOLA Project approach. International Quality of Life Assessment

Instrument translation and evaluation of equivalence and psychometric properties: the Chinese Sense of Coherence Scale

Translating well-established English instruments into target languages other than English and testing cross-cultural validity to prove that the same attributes are being measured in each cultural group or country are required before a multicultural or international study can be conducted and cross-cultural comparisons of study results can be applied. However, rigorous and systematic cross-cultural efforts to test the effectiveness of specific translation methods are rare. This article presents a model of translation processes and empirical validation of the translated instrument through description of the translation of a selected instrument--the Sense of Coherence (SOC) Scale--from English into Chinese. A cyclic process of forward translations, back translations, and expert evaluation of equivalence by bilingual and English speaking experts was conducted to achieve conceptual equivalence between the original and translated instruments. Empirical validation of the Chinese SOC scale data from a group of bilingual Chinese people demonstrated non-identical, but comparable, item and scale means and variances, internal consistency, and relationships to an external criterion. Advantages and difficulties of using multi-rounds, multi-experts, and multi-methods to establish translation equivalence and to validate the translated Chinese SOC scale are discussed.

Validation of the KDQOL-SF: a dialysis-targeted health measure

BACKGROUND

In evaluations of dialysis therapy, an assessment of health-related quality of life (HRQOL) is often important. The aim of this study was to determine the basic psychometric properties, reliability and validity of the short form of the KDQOL i.e. the KDQOL-SF, a dialysis-targeted instrument, and to assess its ability to detect changes over time.

METHODS

In a prospective cohort study (Netherlands Cooperative Study on the Adequacy of Dialysis, NECOSAD), all new adult ESRD patients in 32 different Dutch centers were consecutively enrolled. Demographic, clinical and HRQOL data were obtained 3 and 12 months after the start of chronic dialysis therapy.

RESULTS

The reliability of the KDQOL-SF was supported by test results that were above the recommended minimal values. Validity of KDQOL-SF was confirmed by the hypothesized positive correlations of the overall health rating and renal function, and by the negative correlations between the number of comorbidities and dialysis dose. Moreover, dialysis-targeted dimensions were more sensitive in detecting relevant differences pertaining to kidney diseases than generic dimensions. The KDQOL-SF was able to detect clinical changes over time.

CONCLUSIONS

The psychometric properties of the KDQOL-SF were good, and the different dialysis-targeted dimensions were informative with a high reliability and validity. These results support the application of the KDQOL-SF in studies evaluating dialysis therapy.

French translation and validation of 3 functional disability scales for neck pain

OBJECTIVE

To translate and assess the reliability and the construct validity of 3 functional disability scales for neck pain.

DESIGN

Reliability and validity study.

SETTING

Tertiary care teaching hospital and outpatient clinic.

PARTICIPANTS

One hundred one patients (mean age, 49 y).

INTERVENTION

French translations were obtained by using the "translation-backward translation" method. Adaptations were made after a pilot study.

MAIN OUTCOME MEASURES

Impairment outcome measures (visual analog scale [VAS] pain, neck range of motion, morning stiffness, score of neck sensitivity, radiologic score of Kellgren) and patients' perceived handicap (VAS) were recorded at the baseline visit. Three functional disability scales (Neck Disability Index [NDI], Neck Pain and Disability Scale [NPDS], Northwick Park Neck Pain Questionnaire [NPQ]) were recorded twice, at baseline visit and 24 hours later. Reliability was assessed by using the intraclass correlation coefficient (ICC) and the Bland and Altman method. Construct (convergent and divergent) validity was investigated by using the Spearman rank correlation coefficient and a factor analysis was performed.

RESULTS

Test-retest was excellent for the NPDS and NDI (ICC =.91,.93, respectively) and good for the NPQ (ICC =.84). The Bland and Altman method showed no systematic trend. Expected convergent and divergent validity were observed only for the NPDS; 3 main factors were extracted by factor analysis and explained 78% of the cumulative variance.

CONCLUSION

The 3 translated scales are valid, but the NPDS seems to have the best construct validity.

Pain measurement tools and methods in clinical research in palliative care: recommendations of an Expert Working Group of the European Association of Palliative Care

An Expert Working Group was convened under the auspices of the Steering Committee of the Research Network of the European Association of Palliative Care to review the status of the use of pain measurement tools (PMTs) in palliative care research conducted in a multilingual-multicenter setting. Based on a literature review and on the experts' opinion, the present work recommends that standardized methods should be applied for the use of PMTs in research in palliative care. Visual analogue scales, numerical rating scales, and verbal rating scales are considered valid to assess pain intensity in clinical trials and in other types of studies. Among the multidimensional questionnaires designed to assess pain, the McGill Pain Questionnaire and Brief Pain Inventory are valid in many multilingual versions. Specific recommendations for PMT use and administration, depending on the study type and aim, are reviewed. Special population requirements specific of clinical situations encountered in palliative care (elderly, terminal, cognitively impaired patients, pediatric patients) are also considered.

Quality of life in children and adolescents: a European public health perspective

OBJECTIVES

The measurement of health-related quality of life (HRQOL) is increasingly important as a means of monitoring population health status over time, of detecting sub-groups within the general population with poor HRQOL, and of assessing the impact of public health interventions within a given population. At present, no standardised instrument exists which can be applied with equal relevance in pediatric populations in different European populations. The collaborative European KIDSCREEN project aims to develop a standardised screening instrument for children's quality of life which will be used in representative national and European health surveys. Participants of the project are centres from Austria, France, Germany, Netherlands, Spain, Switzerland, and United Kingdom. By including the instrument in health services research and health reporting, it also aims at identifying children at risk in terms of their subjective health, thereby allowing the possibility of early intervention.

METHODS

Instrument development will be based on constructing a psychometrically sound HRQOL instrument taking into account the existing state of the art. Development will centre on literature searches, expert consultation (Delphi Methods) and focus groups with children and adolescents (8-17 years). According to international guidelines, items will be translated into the languages of the seven participating countries for a pilot test with 2,100 children and their parents in Europe. The final instrument will be used in representative mail and telephone surveys of HRQOL in 1,800 children and their parents per country (total n = 25,200) and normative data will be produced. The potential for implementing the measurement tool in health services and health reporting will also be evaluated in several different research and public health settings. The final analysis will involve national and cross cultural-analysis of the instrument.

RESULTS

The international, collaborative nature of the KIDSCREEN project means it is likely to provide many challenges in terms of producing an instrument which is conceptually and linguistically appropriate for use in many different countries, but it will also provide the opportunity to develop, test and implement the first truly cross-national HRQOL instrument developed for use in children and adolescents. This will help to contribute to a better understanding of perceived health in children and adolescents and to identify populations at risk.

Comparison of German language versions of the QWB-SA and SF-36 evaluating outcomes for patients with prostate disease

BACKGROUND

The quality of well-being scale (QWB) and the Medical Outcome Study 36-item short form (SF-36) are alternative methods for measuring general health outcomes. Few studies compare these approaches against one another and no studies have compared German language versions.

METHOD

A German language version of the self-administered quality of well-being scale (QWB-SA) was developed using forward and back translation methods. The German QWB-SA and a German language version of the SF-36 were administered to clinical population groups with current diagnoses of prostate cancer, benign hyperplasia of the prostate, colon cancer, and rectal cancer. Data were obtained from four German clinics. In addition to the quality of life measures, data on cancer stage and disease state were obtained.

RESULTS

The QWB-SA and SF-36 were highly correlated. The QWB-SA was systematically related to disease state. Those with no symptomatic evidence had the highest scores followed by those who were stable with no metastatic disease and those with metastatic progression. Similar patterns were found for most SF-36 scales although the SF-36 failed to discriminate between those with no evidence of disease and those with stable disease without metastasis.

CONCLUSIONS

Both the QWB-SA and SF-36 perform as expected using German language translations. Although both measures differentiate patients with metastasis from those without symptoms, the QWB-SA better differentiated those with no evidence of disease from those with stable disease without metastasis.

Translation, cultural adaptation, and initial reliability and multitrait testing of the Kidney Disease Quality of Life instrument for use in Japan

BACKGROUND

The Kidney Disease Quality of Life instrument (KDQOL) consists of 79 items: 36 asking about health-related quality of life (HRQOL) in general (the Medical Outcomes Study SF-36) and 43 asking about QOL as it is affected by kidney disease and by dialysis.

AIM

Translation, cultural adaptation and initial reliability and multitrait testing of the KDQOL for use in Japan.

METHODS

Translation and cultural adaptation began with two translations into Japanese, two backtranslations into English, and discussions among the translators, the project coordinators in Japan, and the developers of the original (US-English) version. Focus-group discussions and field testing were followed by analyses of test-retest reliability, internal consistency, and convergent and discriminant construct validity.

RESULTS

All eight of the SF-36 scales met the criterion for internal consistency (Cronbach's alpha ranged from 0.73 to 0.92) and were reproducible (intraclass correlations between test and retest scores ranged from 0.60 to 0.82). Of the 10 kidney-disease-targeted scales, only two had alpha coefficients of less than 0.70: 'sleep' (0.61) and 'quality of social interaction' (0.35). One item on the 'quality of social interaction' scale had a very weak correlation with the remainder of that scale (r = 0.10). Eliminating that item from scoring increased the alpha coefficient of the scale from 0.35 to 0.64. All three items on the 'quality of social interaction' scale had very strong correlations with other scales.

CONCLUSIONS

First, in Japanese patients receiving dialysis the SF-36 scales are internally consistent and their scores are reproducible. Second, with the possible exception of the 'quality of social interaction' scale, the Japanese version of the KDQOL, can provide psychometrically sound kidney-disease-targeted data on quality of life in such patients.

The RAND-36 measure of health-related quality of life

The RAND-36 is perhaps the most widely used health-related quality of life (HRQoL) survey instrument in the world today. It is comprised of 36 items that assess eight health concepts: physical functioning, role limitations caused by physical health problems, role limitations caused by emotional problems, social functioning, emotional well-being, energy/fatigue, pain, and general health perceptions. Physical and mental health summary scores are also derived from the eight RAND-36 scales. This paper provides example applications of the RAND-36 cross-sectionally and longitudinally, provides information on what a clinically important difference is for the RAND-36 scales, and provides guidance for summarizing the RAND-36 in a single number. The paper also discusses the availability of the RAND-36 in multiple languages and summarizes changes that are incorporated in the latest version of the survey.

[French translation and validation of a functional disability scale for neck pain]

OBJECTIVES

To translate and to assess the reliability and the construct validity of the French translation of the Neck Pain and Disability Scale (NPDS), an American functional disability scale for neck pain.

PATIENTS AND METHODS

Non randomised prospective study, where patients with neck disorders were included. Impairment outcomes measures (VAS Pain, range of motion of neck, score of neck sensitivity, radiologic score of Kellgren) and patientsperceived handicap (VAS) were recorded at the baseline visit. Disability was assessed with the NPDS, that was recorded twice, at baseline visit and 24 hours later. Reliability was assessed using the intraclass correlation coefficient (ICC) and the Bland and Altman method. Construct (convergent and divergent) validity was investigated using the Spearman rank correlation coefficient and a factor analysis was performed.

RESULTS

One hundred and one patients were included. French versions were obtained using the "translation/backward translation" method. Expected convergent (r = 0.51 with VAS Pain, 0.63 with VAS Functional Disability, 0.67 with VAS Handicap) and divergent (r = 0.39 and 0.49 respectively for the anxiety and depression scores of HAD, palpation sensitivity r = 0.31, neck mobility r = - 0.45 and 0.28, and Kellgrens radiologic score r = 0.04) validity were observed, suggested good construct validity. Test-retest was excellent for NPDS with ICC = 0.91. The Bland and Altman method showed distribution of differences homogenous and no systematic trend. Three mains factors were extracted by factors analysis of the NPDS, and explained 78% of the cumulative variance.

CONCLUSION

The French version of NPDS has good metrologic qualities. This scale can be used in clinical practice to assess disability in neck pain and to normalise disability assessment.

Criteria for assessing the tools of disability outcomes research

To recommend instrument assessment criteria, deriving from psychometric textbooks and articles and disability and research experts, for reviewing and assessing surveys and questionnaires for disability outcomes research. Traditional criteria are recommended, including psychometric properties of validity, reliability, and sensitivity to change, as are newer statistical methods for assessing scaling properties, such as Rasch analysis. Special consideration is needed for generic instruments that may be poorly scaled for disability research. Pragmatic aspects of data collection, including acceptability and disability accommodation, also are recommended.

American translation, modification, and validation of the St. George's Respiratory Questionnaire

BACKGROUND

The St. George's Respiratory Questionnaire (SGRQ) is a 50-item health status survey specific for chronic obstructive pulmonary disease (COPD) and other respiratory diseases that is available in British English but not American English. The SGRQ's symptom-reporting component requires a 1-year reporting period, which may be too long for reliable and accurate patient recall.

OBJECTIVES

The objectives of the present study were to translate the SGRQ from British to American English, modify the reporting period of the symptom-reporting component from 1 year to 1 month, and assess the reliability, validity, and sensitivity to change of this translated modified version in a sample of patients with COPD.

METHODS

Based on input from American patients with COPD and health professionals, the SGRQ was translated into American English (SGRQ-A) and then translated back to British English. For SGRQ-A reliability and validity studies, patients were asked to report symptoms experienced over 1 year (reporting period in the original SGRQ) and 1 month (modification made to SGRQ-A). We evaluated 102 patients with COPD (50% female; mean age, 68 years; mean forced expiratory volume in 1 second [FEV1], 1.01 L) at an administrative session before and after completion of a pulmonary rehabilitation program. The SGRQ-A, Chronic Respiratory Disease Questionnaire (CRQ), 36-Item Short Form Health Survey (SF-36), 6-minute walk (6MW), Medical Research Council (MRC) Dyspnea scale, and pulmonary function tests (FEV1 and % predicted FEV1) were used in the assessment battery.

RESULTS

The SGRQ-A showed good agreement with the original SGRQ when translated back to British English. Internal reliability (Cronbach alpha) was > 0.70 for all SGRQ-A components except the 1-year symptom-reporting component. Test-retest intraclass correlations were 0.795 to 0.900. Construct validity was strengthened when all SGRQ-A components (except 1-year symptoms and most 1-month symptoms) correlated (P < or = 0.01) with the MRC Dyspnea scale, 6MW, all SF-36 concept scores, and 80% of CRQ domains (r = 0.30-0.72). Discriminate validity was demonstrated when all components of the SGRQ-A with the modified 1-month symptom-reporting period were shown to discriminate better between disease-severity groups (based on patient self-reports of disease severity) than did pulmonary function tests and the 6MW. Responsiveness of the SGRQ-A to change in health status was demonstrated when scores on the Symptoms-1 month and Total-1 month components detected significant improvements in patients' health status (P = 0.02 and P = 0.04, respectively).

CONCLUSION

The SGRQ-A with a modified 1-month symptom-reporting period demonstrated reliability and validity in this sample of patients with COPD. Key words: chronic obstructive pulmonary disease, St. George's Respiratory Questionnaire, American translation, reliability, validity, symptom recall.

Validity and reliability of the SF-36 Health Survey Questionnaire in patients with coronary artery disease

The validity and reliability of the SF-36 has been studied in 185 patients hospitalized with suspected ischemic cardiopathy, classified into four groups (AMI, unstable angina, nonischemic cardiologies, and absence of cardiologies). The validity of the construct has been analyzed by means of the association of the SF-36 with sociodemographic and clinical variables, and with diagnostic groups. The correlation of the subscales with GHQ-28 scores and the factorial structure have been studied. Internal consistency was measured by Cronbach's alpha and the item-internal consistency and item-discriminant validity. The validation result was as expected, although the scores were significantly lower in patients with unstable angina, only in the PF, VT, and GH subscales. The correlations with the GHQ-28 were high for MH and VT. The internal consistency was high (Cronbach's alpha 0.72-0.94). Factorial analysis identified eight factors, with the "anxiety" component of subscale MH remaining as an independent factor. These results suggest that the SF-36 is a useful scale for the differentiated clinical forms of ischemic cardiopathy, with the additional capability of reflecting the level of anxiety in these patients.

Tests of data quality, scaling assumptions, and reliability of the Danish SF-36

We used general population data (n = 4084) to examine data completeness, response consistency, tests of scaling assumptions, and reliability of the Danish SF-36 Health Survey. We compared traditional multitrait scaling analyses to analyses using polychoric correlations and Spearman correlations. The frequency of missing values was low, except for elderly people and people with lower levels of education. Response consistency was high and compared well with results for the U.S. SF-36. For respondents with computable scales in all eight domains, scaling assumptions (item internal consistency, item discriminant validity, equal item-own scale correlations, and equal variances) were satisfactory in the total sample and in all subgroups. The SF-36 could discriminate between levels of health in all subgroups, but there were skewness, kurtosis, and ceiling effects in many subgroups (elderly people and people with chronic diseases excepted). Concerning correlation methods, we found interesting differences indicating advantages of using methods that do not assume a normal distribution of answers as an addition to traditional methods.

The Italian SF-36 Health Survey: translation, validation and norming

This article reports on the development and validation of the Italian SF-36 Health Survey using data from seven studies in which an Italian version of the SF-36 was administered to more than 7000 subjects between 1991 and 1995. Empirical findings from a wide array of studies and diseases indicate that the performance of the questionnaire improved as the Italian translation was revised and that it met the standards suggested by the literature in terms of feasibility, psychometric tests, and interpretability. This generally satisfactory picture strengthens the idea that the Italian SF-36 is as valid and reliable as the original instrument and applicable and valid across age, gender, and disease. Empirical evidence from a cross-sectional survey carried out to norm the final version in a representative sample of 2031 individuals confirms the questionnaire's characteristics in terms of hypothesized constructs and psychometric behavior and gives a better picture of its external validity (i.e., robustness and generalizability) when administered in settings that are very close to real world.

Translation, validation, and norming of the Dutch language version of the SF-36 Health Survey in community and chronic disease populations

The primary objectives of this research were to translate, validate, and generate normative data on the SF-36 Health Survey for use among Dutch-speaking residents of the Netherlands. Translation of the SF-36 into Dutch followed the stepwise, iterative procedures developed by the IQOLA Project. Following extensive pilot testing, the SF-36 was administered to: (1) a random sample of adult residents of Amsterdam (n = 4172); (2) a random, nationwide sample of adults (n = 1742); (3) a sample of migraine sufferers (n = 423); and (4) a sample of cancer patients undergoing active anti-neoplastic treatment (n = 485). Data quality across the four studies was consistently high. The rates of missing data ranged from 1% to 5% at the item level, and from 1.2% to 2.6% at the scale level. Multitrait scaling analysis confirmed the hypothesized scale structure of the SF-36 and associated scale scoring in all four samples. Cronbach's alpha coefficients surpassed the 0.70 criterion for group comparisons in all but one case (the Social Functioning scale in the cancer sample), with a mean alpha coefficient across all scales and samples of 0.84. Known-group comparisons yielded consistent support for the validity of the SF-36. In the two community samples, statistically significant differences in SF-36 mean scale scores were observed as a function of age, gender, and the prevalence of chronic health conditions. In the migraine and cancer samples, mean SF-36 scale scores varied significantly as a function of various indicators of disease severity. The SF-36 profiles for the two community samples were highly similar. The cancer sample yielded the lowest SF-36 scores, with the migraine sample holding an intermediate position. On-going studies will generate data on the responsiveness of the SF-36 to within-group changes in health over time. Efforts are underway to translate and validate the questionnaire for use among ethnic minority groups in the Netherlands.

Testing Dutch and French translations of the SF-36 Health Survey among Belgian angina patients

The psychometric properties of the Belgian Dutch and French translations of the SF-36 Health Survey were evaluated in a sample of 4448 Belgian patients with angina enrolled in a 6-month treatment study. Missing data were rare (<2%), and tests of both item internal consistency and item discriminant validity were satisfactory in both languages. Cronbach's alpha coefficient ranged from 0.81 to 0.91 (Dutch) and 0.82 to 0.92 (French). SF-36 scales discriminated between groups of patients differing in age and in the number of weekly angina attacks, change over 6 months in the number of weekly angina attacks and physician assessment of change in physical condition both were significantly related to changes in SF-36 scale scores. On average, scale scores for French-speaking patients were lower than for Dutch-speaking patients, most notably for Vitality and Mental Health. The average change in SF-36 scale scores over 6 months, in relation to change in clinical criteria, was similar in both language groups. The psychometric properties of the Belgian Dutch and French translations should be tested further in Belgium to determine whether the generally favorable results reported here can be replicated in other samples.

Use of structural equation modeling to test the construct validity of the SF-36 Health Survey in ten countries: results from the IQOLA Project. International Quality of Life Assessment

A crucial prerequisite to the use of the SF-36 Health Survey in multinational studies is the reproduction of the conceptual model underlying its scoring and interpretation. Structural equation modeling (SEM) was used to test these aspects of the construct validity of the SF-36 in ten IQOLA countries: Denmark, France, Germany, Italy, the Netherlands, Norway, Spain, Sweden, the United Kingdom, and the United States. Data came from general population surveys fielded to gather normative data. Measurement and structural models developed in the United States were cross-validated in random halves of the sample in each country. SEM analyses supported the eight first-order factor model of health that underlies the scoring of SF-36 scales and two second-order factors that are the basis for summary physical and mental health measures. A single third-order factor was also observed in support of the hypothesis that all responses to the SF-36 are generated by a single, underlying construct--health. In addition, a third second-order factors, interpreted as general well-being, was shown to improve the fit of the model. This model (including eight first-order factors, three second-order factors, and one third-order factor) was cross-validated using a holdout sample within the United States and in each of the nine other countries. These results confirm the hypothesized relationships between SF-36 items and scales and justify their scoring in each country using standard algorithms. Results also suggest that SF-36 scales and summary physical and mental health measures will have similar interpretations across countries. The practical implications of a third second-order SF-36 factor (general well-being) warrant further study.

Testing the measurement properties of the Spanish version of the SF-36 Health Survey among male patients with chronic obstructive pulmonary disease. Quality of Life in COPD Study Group

The aim of this article is to evaluate the measurement properties of the Spanish version of the SF-36 Health Survey (SF-36). In total, 321 male chronic obstructive pulmonary disease (COPD) patients attending hospital outpatient or primary health clinics were cross-sectionally administered the SF-36, the St. George's Respiratory Questionnaire (SGRQ), and a dyspnea scale. A clinical measure of respiratory function, the proportion of the predicted Forced Expiratory Volume in 1 second (%FEV1) was also obtained. Internal consistency, central tendency, and dispersion statistics of scores were calculated, as well as the percentage of respondents with the highest and lowest scores for each scale and correlations between health status and clinical measures. All patients completed the SF-36 questionnaire, and less than 1% of items were missing. The proportion of patients with the worst possible score (floor effect) ranged from 0.9-20.1% among the different scales. The proportion of patients achieving the best possible score (ceiling effect) ranged from 0-61%. Cronbach's alpha coefficients were above 0.75 except for one scale (Social Functioning, alpha = 0.55). SF-36 scores were moderate to highly correlated with SGRQ scores (coefficients ranged from -.41 to -.79). Correlations were moderate to high with dyspnea and lower but statistically significant with %FEV1. A clear gradient of SF-36 scores was found according to dyspnea levels and disease staging based on %FEV1 impairment, the gradient being more marked for the Physical Functioning, Role-Physical, and General Health scales. Data presented suggest that the Spanish version of the SF-36 is acceptable, valid, and reliable in COPD patients. Although more studies are needed, this version is adequate in international comparisons of health outcomes.

The Danish SF-36 Health Survey: translation and preliminary validity studies

This article reports on the Danish translation of SF-36 and discusses the procedures used for translation improvement, translation evaluation, and scale evaluation. We followed the standard procedures of the International Quality of Life Assessment (IQOLA) Project including forward and backward translation, independent assessment of translation quality, assessment of response-choice weighting through visual analogue scale (VAS) investigations, and psychometric testing of the translated questionnaire. We found that backward translation, independent quality assessment, and VAS studies provided useful information for translation improvement. The Danish SF-36 received a favorable translation evaluation by independent rating; however, interrater agreement was low. Preliminary validity studies generally supported the internal consistency and homogeneity of the Danish SF-36, and the questionnaire performed satisfactorily in distinguishing depressive patients from nonpatients. On the basis of this and other studies, we recommend use of the Danish SF-36 in research.

Comparison of Rasch and summated rating scales constructed from SF-36 physical functioning items in seven countries: results from the IQOLA Project. International Quality of Life Assessment

Rasch models for polytomous items were used to assess the scaling assumptions and compare item response patterns in the 10-item SF-36 physical functioning scale (PF-10) for general population respondents in Denmark, Germany, Italy, the Netherlands, Sweden, the United Kingdom, and the United States. The Rasch model of physical functioning developed in the United States was compared to models for other countries, and each country was compared to a multinational composite. Strong scale congruence across the seven countries was demonstrated; items that varied between countries and from the composite may reflect unique cultural response patterns or differences in translation. Scoring algorithms based on the Rasch model for each country were superior to the current Likert scoring in tests of relative validity (RV) in discriminating among age groups in all countries. In relation to the Likert PF-10 scoring (RV = 1.00), scores estimated using the Rasch rating scale model achieve a median RV of 1.31 (range: 1.01-1.59), while the Rasch partial credit model attained a median RV of 1.44 (range: 1.01-2.23). Rasch models hold good potential for improving health status measures, estimating individual scores when responses to scale items are missing, and equating scores across countries.

Adaptation and validation of the SF-36 Health Survey for use in Australia

This article reports on the process undertaken to adapt the U.S. version of the SF-36 to an Australian setting. In addition, the results of psychometric testing, using the International Quality of Life Assessment (IQOLA) Project process and standards, is also reported. The adaptation process involved a number of steps including: a series of forward and backward translations; ratings of the difficulty of translating the SF-36 and the quality of the resulting translation. To assess the psychometric properties of the Australian form, a random sample of people residing in the Hunter region of New South Wales, Australia, were invited to complete the SF-36 with 855 respondents consenting to complete the measure. Principal components analyses supported the assumption of two factors underlying the measure with the percentage of variance explained by these factors ranging from between 0.66 and 0.77. Demonstrable internal consistency (both item and scale) and test-retest reliability were also found.

The Swedish SF-36 Health Survey III. Evaluation of criterion-based validity: results from normative population

Assumptions of the variation in SF-36 scale scores were tested in relation to external criteria in 8930 respondents comprising the Swedish norming population. Physical health scales were strongly associated with age, while small differences were found for the Mental Health scale across age groups. Females reported poorer health than males, particularly in ages between 30-40 and over 70. Worse health profiles were associated with social risk factors (unemployment, divorce, etc.). The disability pension rate was strongly related to reduced Physical Functioning and increased Bodily Pain. The use of medical care was reflected in general health scores (i.e., the lower the scale score, the higher the care consumption). Self-reported physical and psychological symptoms were selectively related to SF-36 scales. All SF-36 scales, except Mental Health, were more strongly related to ratings of health satisfaction than to global quality of life. Combinations of the SF-36 well-being scales explained a substantial part of the variance of these ratings. In conclusion, the performed criterion-validity tests support the cross-cultural stability of the SF-36.

Methods for validating and norming translations of health status questionnaires: the IQOLA Project approach. International Quality of Life Assessment

This article briefly summarizes methods used in the empirical validation of translations of the SF-36 Health Survey. In addition, information about the IQOLA Project norming protocol and 13 general population norming samples analyzed in this supplement is provided.

Differential item functioning in the Danish translation of the SF-36

Statistical analyses of Differential Item Functioning (DIF) can be used for rigorous translation evaluations. DIF techniques test whether each item functions in the same way, irrespective of the country, language, or culture of the respondents. For a given level of health, the score on any item should be independent of nationality. This requirement can be tested through contingency-table methods, which are efficient for analyzing all types of items. We investigated DIF in the Danish translation of the SF-36 Health Survey, using two general population samples (USA, n = 1,506; Denmark, n = 3,950). DIF was identified for 12 out of 35 items. These results agreed with independent ratings of translation quality, but the statistical techniques were more sensitive. When included in scales, the items exhibiting DIF had only a little impact on conclusions about cross-national differences in health in the general population. However, if used as single items, the DIF items could seriously bias results from cross-national comparisons. Also, the DIF items might have larger impact on cross-national comparison of groups with poorer health status. We conclude that analysis of DIF is useful for evaluating questionnaire translations.

Cross-cultural comparisons of the content of SF-36 translations across 10 countries: results from the IQOLA Project. International Quality of Life Assessment

Increasingly, translated and culturally adapted health-related quality of life measures are being used in cross-cultural research. To assess comparability of results, researchers need to know the comparability of the content of the questionnaires used in different countries. Based on an item-by-item discussion among International Quality of Life Assessment (IQOLA) investigators of the content of the translated versions of the SF-36 in 10 countries, we discuss the difficulties that arose in translating the SF-36. We also review the solutions identified by IQOLA investigators to translate items and response choices so that they are appropriate within each country as well as comparable across countries. We relate problems and solutions to ratings of difficulty and conceptual equivalence for each item. The most difficult items to translate were physical functioning items that refer to activities not common outside the United States and items that use colloquial expressions in the source version. Identifying the origin of the source items, their meaning to American English-speaking respondents and American English synonyms, in response to country-specific translation issues, greatly helped the translation process. This comparison of the content of translated SF-36 items suggests that the translations are culturally appropriate and comparable in their content.

Tests of data quality, scaling assumptions, and reliability of the SF-36 in eleven countries: results from the IQOLA Project. International Quality of Life Assessment

Data from general population samples in 11 countries (n = 1483 to 9151) were used to assess data quality and test the assumptions underlying the construction and scoring of multi-item scales from the SF-36 Health Survey. Across all countries, the rate of item-level missing data generally was low, although slightly higher for items printed in the grid format. In each country, item means generally were clustered as hypothesized within scales. Correlations between items and hypothesized scales were greater than 0.40 with one exception, supporting item internal consistency. Items generally correlated significantly higher with their own scale than with competing scales, supporting item discriminant validity. Scales could be constructed for 93-100% of respondents. Internal consistency reliability of the eight SF-36 scales was above 0.70 for all scales, with two exceptions. Floor effects were low for all except the two role functioning scales; ceiling effects were high for both role functioning scales and also were noteworthy for the Physical Functioning, Bodily Pain, and Social Functioning scales in some countries. These results support the construction and scoring of the SF-36 translations in these 11 countries using the method of summated ratings.

Overview of the SF-36 Health Survey and the International Quality of Life Assessment (IQOLA) Project

This article presents information about the development and evaluation of the SF-36 Health Survey, a 36-item generic measure of health status. It summarizes studies of reliability and validity and provides administrative and interpretation guidelines for the SF-36. A brief history of the International Quality of Life Assessment (IQOLA) Project is also included.

Translation, adaptation, and validation of the SF-36 Health Survey for use in Japan

Development of the Japanese SF-36 was completed in two phases: Phase 1: Japanese version 1.1 was produced according to International Quality of Life Assessment (IQOLA) project guidelines, but some results of psychometric tests were unexpected. First, scores varied little across physical-functioning items. Second, using factor analysis, we could not clearly distinguish the scales designed to measure the "physical" component of quality of life from those designed to measure the "mental" component. Phase 2: Focus-group discussions revealed that limited had often been interpreted as limited by a doctor. Therefore, is difficult to do was used instead (version 1.2). Results of two surveys indicated that version 1.2 yields scores that are reliable by internal consistency and test-retest standards and yields two principal components. In Japan, however, the pattern of correlations between some scales and the principal components differs from that in the United States. Iterative use of qualitative and quantitative methods was very important in developing the Japanese SF-36.

The factor structure of the SF-36 Health Survey in 10 countries: results from the IQOLA Project. International Quality of Life Assessment

Studies of the factor structure of the SF-36 Health Survey are an important step in its construct validation. Its structure is also the psychometric basis for scoring physical and mental health summary scales, which are proving useful in simplifying and interpreting statistical analyses. To test the generalizability of the SF-36 factor structure, product-moment correlations among the eight SF-36 Health Survey scales were estimated for representative samples of general populations in each of 10 countries. Matrices were independently factor analyzed using identical methods to test for hypothesized physical and mental health components, and results were compared with those published for the United States. Following simple orthogonal rotation of two principal components, they were easily interpreted as dimensions of physical and mental health in all countries. These components accounted for 76% to 85% of the reliable variance in scale scores across nine European countries, in comparison with 82% in the United States. Similar patterns of correlations between the eight scales and the components were observed across all countries and across age and gender subgroups within each country. Correlations with the physical component were highest (0.64 to 0.86) for the Physical Functioning, Role Physical, and Bodily Pain scales, whereas the Mental Health, Role Emotional, and Social Functioning scales correlated highest (0.62 to 0.91) with the mental component. Secondary correlations for both clusters of scales were much lower. Scales measuring General Health and Vitality correlated moderately with both physical and mental health components. These results support the construct validity of the SF-36 translations and the scoring of physical and mental health components in all countries studied.