Cross-Cultural Evaluation of Health Status Using Item Response Theory

Baduanjin exercise for patients with breast cancer: A systematic review and meta-analysis

OBJECTIVE

Baduanjin exercise is a traditional Chinese mind-body exercise routine characterized by slow, coordinated, and sequential movements. We have performed the first meta-analysis on the main effect of Baduanjin exercise in patients with breast cancer.

METHODS

This study followed the 2020 PRISMA guideline. We searched for randomized controlled trials in PubMed, Embase, Cochrane Library, Web of Science, Clinical Trials.gov, Chinese National Knowledge Infrastructure, Wanfang Data Information Site, Chinese Biomedical Database, and Chinese Science and Technique Journals Database through 31 August 2022. Data were analyzed for the outcomes of quality of life, anxiety, and depression. Review Manager 5.4 software was used for data analysis.

RESULTS

Seven randomized controlled trials with a total of 537 patients with breast cancer were examined. Compared with the control therapies, Baduanjin exercise significantly improved the total quality of life score (SMD = 0.83; 95 % CI, 0.58-1.08; P < 0.00001) and in two associated domains: emotional well-being (SMD = 0.67; 95 % CI, 0.26-1.07; P = 0.001), functional well-being (SMD = 0.55; 95 % CI, 0.30-0.79; P < 0.00001) and breast cancer subscale (SMD = 0.39; 95 % CI, 0.02-0.77; P = 0.04). Meanwhile, it significantly reduced anxiety score (SMD = - 0.60; 95 % CI, - 1.15 to - 0.05; P = 0.03) and in depression score (SMD = - 0.70 95 % CI, - 0.97 to - 0.42; P < 0.00001). None adverse event was reported.

CONCLUSION

The meta-analysis suggests that Baduanjin exercise is an effective and safe exercise for improving quality of life and alleviating depression and anxiety in patients with breast cancer. Significant methodological concerns of the included studies limit the interpretation of the results. For future trials of Baduanjin exercise on BC, we highlight the importance of adopting more rigorous study design in terms of assessor blinding, hypothesis/purpose blinding, allocation concealment, objective outcome selection and consistent reporting of adverse events.

Psychometric properties of the social interaction anxiety scale and the social phobia scale in Hungarian adults and adolescents

BACKGROUND

Although social anxiety disorder is one of the most frequent disorders, it often remained unrecognized. Utilizing brief, yet reliable screening tools, such as the Social Interaction Anxiety Scale (SIAS-6) and the Social Phobia Scale (SPS-6) are helping to solve this problem in parts of Western Europe and the US. Still some countries, like Hungary, lag behind. For this purpose, previous studies call for further evidence on the applicability of the scales in various populations and cultures, as well as the elaborative validity of the short forms. Here, we aimed to provide a thorough analysis of the scales in five studies. We employed item response theory (IRT) to explore the psychometric properties of the SIAS-6 and the SPS-6 in Hungarian adults (n = 3213, age range:19-80) and adolescents (n = 292, age range:14-18).

RESULTS

In both samples, IRT analyses demonstrated that the items of SIAS-6 and SPS-6 had high discriminative power and cover a wide range of the latent trait. Using various subsamples, we showed that (1) the scales had excellent convergent and divergent validity in relation to domains of anxiety, depression, and cognitive emotion regulation in both samples. Further, that (2) the scales discriminated those with a history of fainting or avoidance from those without such history. Lastly, (3) the questionnaires can discriminate people diagnosed with social anxiety disorder (n = 30, age range:13-71) and controls.

CONCLUSIONS

These findings suggest that the questionnaires are suitable for screening for SAD in adults and adolescents. Although the confirmation of the two-factor structure may be indicative of the validity of the "performance only" specifier of SAD in DSM-V, the high correlation between the factors and the similar patter of convergent validity might indicate that it is not a discrete entity but rather a part of SAD; and that SAD is latently continuous.

Efficacy and Safety of Ribociclib With Letrozole in US Patients Enrolled in the MONALEESA-2 Study

BACKGROUND

In the Mammary Oncology Assessment of LEE011's (Ribociclib's) Efficacy and Safety (MONALEESA-2) study, combination treatment with the selective inhibitor of cyclin-dependent kinases 4/6 ribociclib with letrozole significantly improved progression-free survival (PFS) versus letrozole alone in postmenopausal women with hormone receptor-positive HR⁺/HER2^- advanced breast cancer (ABC). Herein we present results from the subset of US patients enrolled in MONALEESA-2.

PATIENTS AND METHODS

Postmenopausal women with HR⁺/HER2^- ABC without previous treatment for advanced disease were randomized (1:1) to ribociclib 600 mg/d (3 weeks on/1 week off) with letrozole 2.5 mg/d (continuous) or placebo with letrozole. The primary end point was locally assessed PFS.

RESULTS

Overall, 213 US patients were enrolled in MONALEESA-2 (ribociclib, n = 100; placebo, n = 113). Baseline characteristics were similar between treatment groups and consistent with the global population. With a median follow-up of 27 months, 38 (38%) and 29 (26%) patients in the ribociclib and placebo groups, respectively, had continued to receive treatment. Median PFS was 27.6 months with ribociclib and 15.0 months with placebo (hazard ratio, 0.53). The most common all-cause adverse events were neutropenia (ribociclib, 72.0% [n = 72]; placebo, 4.6% [n = 5]), nausea (ribociclib, 69.0% [n = 69]; placebo, 44.0% [n = 48]), and fatigue (ribociclib, 60.0% [n = 60]; placebo, 50.5% [n = 55]). Two patients (ribociclib, 2.0%; placebo, 0%) experienced febrile neutropenia.

CONCLUSION

In the US subset of MONALEESA-2, ribociclib with letrozole showed superior efficacy versus letrozole alone. These findings are consistent with the global population and support first-line use of ribociclib with letrozole in patients with HR⁺/HER2^- ABC.

Evaluation of cross-cultural adaptation and measurement properties of breast cancer-specific quality-of-life questionnaires: a systematic review

PURPOSE

To assess the procedures of translation, cross-cultural adaptation, and measurement properties of breast cancer-specific quality-of-life questionnaires.

METHODS

Searches were conducted in the databases MEDLINE, EMBASE, CINAHL, and SciELO using the keywords: "Questionnaires," "Quality of life," and "Breast cancer." The studies were analyzed in terms of methodological quality according to the guidelines for the procedure of cross-cultural adaptation and the quality criteria for measurement properties of questionnaires.

RESULTS

We found 24 eligible studies. Most of the articles assessed the translation and measurement properties of the instrument EORTC QLQ-BR23. Description about translation and cross-cultural adaptation was incomplete in 11 studies. Translation and back translation were the most tested phases, and synthesis of the translation was the most omitted phase in the articles. Information on assessing measurement properties was provided incompletely in 23 articles. Internal consistency was the most tested property in all of the eligible articles, but none of them provided information on agreement. Construct validity was adequately tested in only three studies that used the FACT-B and QLQ-BR23. Eight articles provided information on reliability; however, only four found positive classification. Responsiveness was tested in four articles, and ceiling and floor effects were tested in only three articles. None of the instruments showed fully adequate quality.

CONCLUSION

There is limited evidence on cross-cultural adaptations and measurement properties; therefore, it is recommended that caution be exercised when using breast cancer-specific quality-of-life questionnaires that have been translated, adapted, and tested.

Quality of life in patients with breast cancer and their rehabilitation needs

Objective: We conducted a cross sectional study to investigate the quality of life (QOL) in breast cancer patients after treatment for one year and identify factors which may facilitate improvements in health care for breast cancer.

Methods: A total of 154 patients of breast cancer were collected from The First Affiliated Hospital of Harerbin Medical University during May 2008 and May 2010, and they were divided into three groups. The quality of life was assessed by Functional assessment of cancer therapy- breast (FACT-B) version 4, and a semi-structured interview was used to investigate the information and rehabilitation needs of the breast cancer patients.

Results: Group II had the best social well-being, functional well-being and Total FACT-G among the three groups. Group III had the best physical well-being, emotional well-being, breast specific subscales, total FACT-B and TOI among the three groups. Higher PWB scores were significantly correlation with lower tumor stage; increased SWB scores were significantly correlated with education and occupation, and lower EWB scores were correlated with younger aged women and higher tumor stage (< 40 years). The semi-structured investigation showed all of them want to receive tumor markers detection and PET scan to prevent recurrence. 56% of these patients were worried about symptoms. 42% of the patients reported they had restriction in sexual relationship, and 57% wanted to improve their body image and reconstruction surgery.

Conclusions: Breast cancer patients should be followed up for their quality of life and provided effective therapy for their physical and psychological problems.

Attachment-oriented psychological intervention for couples facing breast cancer: protocol of a randomised controlled trial

Background

There is evidence that both breast cancer patients and their partners are affected emotionally, when facing a breast cancer diagnosis. Several couple interventions have been evaluated, but there is a need for couple intervention studies with a clear theoretical basis and a strong design. The Hand in Hand intervention is designed to enhance interdependent coping in the couples and to address patients and partners that are both initially distressed and non-distressed.

Methods

The Hand in Hand study is a randomised controlled trial among 199 breast cancer patients and their partners. Couples were randomised to 4-8 couple sessions with a psychologist in addition to usual care, or to usual care only, approximately 2 months after the patients’ primary surgery date. The intervention was delivered within 3 months, and outcomes were assessed prior to randomisation and 5 and 10 months after primary surgery date. The primary outcome is patients’ cancer-specific distress at the 5-month follow-up measured by the Impact of Event Scale. Secondary outcomes are assessed for both breast cancer patients and partners. These outcomes are: general distress, symptoms of anxiety and depression, health-related quality of life and measures of dyadic adjustment, intimacy and partner involvement. Cancer-specific distress is also assessed for partners.

Eligible patients were women ≥ 18 years newly diagnosed with primary breast cancer, cohabiting with a male partner, having no previous cancer diagnoses, receiving no neo-adjuvant treatment, having no history of hospitalisation due to psychosis, and able to read and speak Danish. Partners were eligible if they could read and speak Danish and were ≥ 18 years.

Discussion

This study investigates the effect of an attachment-oriented psychological intervention for breast cancer patients and their partners. The intervention has a theoretical framework and a strong design. If proven effective, this intervention would be helpful in optimising psychosocial care and rehabilitation of couples coping with breast cancer.

Trial registration

ClinicalTrials.gov identifier: NCT01368380.

Listening in on difficult conversations: an observational, multi-center investigation of real-time conversations in medical oncology

BACKGROUND

The quality of communication in medical care has been shown to influence health outcomes. Cancer patients, a highly diverse population, communicate with their clinical care team in diverse ways over the course of their care trajectory. Whether that communication happens and how effective it is may relate to a variety of factors including the type of cancer and the patient's position on the cancer care continuum. Yet, many of the routine needs of cancer patients after initial cancer treatment are often not addressed adequately. Our goal is to identify areas of strength and areas for improvement in cancer communication by investigating real-time cancer consultations in a cross section of patient-clinician interactions at diverse study sites.

METHODS/DESIGN

In this paper we describe the rationale and approach for an ongoing observational study involving three institutions that will utilize quantitative and qualitative methods and employ a short-term longitudinal, prospective follow-up component to investigate decision-making, key topics, and clinician-patient-companion communication dynamics in clinical oncology.

DISCUSSION

Through a comprehensive, real-time approach, we hope to provide the fundamental groundwork from which to promote improved patient-centered communication in cancer care.

Developing core sets for patients with obstetricbrachial plexus injury based on the International Classificationof Functioning, Disability and Health

Background

Symptoms of obstetric brachial plexus injury (OBPI) vary widely over the course of time and from individual to individual and can include various degrees of denervation, muscle weakness, contractures, bone deformities and functional limitations. To date, no universally accepted overall framework is available to assess the outcome of patients with OBPI. The objective of this paper is to outline the proposed process for the development of International Classification of Functioning, Disability and Health (ICF) Core Sets for patients with an OBPI.

Methods

The first step is to conduct four preparatory studies to identify ICF categories important for OBPI: a) a systematic literature review to identify outcome measures, b) a qualitative study using focus groups, c) an expert survey and d) a cross-sectional, multicentre study. A first version of ICF Core Sets will be defined at a consensus conference, which will integrate the evidence from the preparatory studies. In a second step, field-testing among patients will validate this first version of Core Sets for OBPI.

Discussion

The proposed method to develop ICF Core Sets for OBPI yields a practical tool for multiple purposes: for clinicians to systematically assess and evaluate the individual’s functioning, for researchers to design and compare studies, and for patients to get more insight into their health problems and their management.

Cross-cultural differences in knee functional status outcomes in a polyglot society represented true disparities not biased by differential item functioning

BACKGROUND

Comparative effectiveness research across cultures requires unbiased measures that accurately detect clinical differences between patient groups.

OBJECTIVE

The purpose of this study was to assess the presence and impact of differential item functioning (DIF) in knee functional status (FS) items administered using computerized adaptive testing (CAT) as a possible cause for observed differences in outcomes between 2 cultural patient groups in a polyglot society.

DESIGN

This study was a secondary analysis of prospectively collected data.

METHODS

We evaluated data from 9,134 patients with knee impairments from outpatient physical therapy clinics in Israel. Items were analyzed for DIF related to sex, age, symptom acuity, surgical history, exercise history, and language used to complete the functional survey (Hebrew versus Russian).

RESULTS

Several items exhibited DIF, but unadjusted FS estimates and FS estimates that accounted for DIF were essentially equal (intraclass correlation coefficient [2,1]>.999). No individual patient had a difference between unadjusted and adjusted FS estimates as large as the median standard error of the unadjusted estimates. Differences between groups defined by any of the covariates considered were essentially unchanged when using adjusted instead of unadjusted FS estimates. The greatest group-level impact was <0.3% of 1 standard deviation of the unadjusted FS estimates.

LIMITATIONS

Complete data where patients answered all items in the scale would have been preferred for DIF analysis, but only CAT data were available.

CONCLUSIONS

Differences in FS outcomes between groups of patients with knee impairments who answered the knee CAT in Hebrew or Russian in Israel most likely reflected true differences that may reflect societal disparities in this health outcome.

Differential item functioning (DIF) analyses of health-related quality of life instruments using logistic regression

BACKGROUND

Differential item functioning (DIF) methods can be used to determine whether different subgroups respond differently to particular items within a health-related quality of life (HRQoL) subscale, after allowing for overall subgroup differences in that scale. This article reviews issues that arise when testing for DIF in HRQoL instruments. We focus on logistic regression methods, which are often used because of their efficiency, simplicity and ease of application.

METHODS

A review of logistic regression DIF analyses in HRQoL was undertaken. Methodological articles from other fields and using other DIF methods were also included if considered relevant.

RESULTS

There are many competing approaches for the conduct of DIF analyses and many criteria for determining what constitutes significant DIF. DIF in short scales, as commonly found in HRQL instruments, may be more difficult to interpret. Qualitative methods may aid interpretation of such DIF analyses.

CONCLUSIONS

A number of methodological choices must be made when applying logistic regression for DIF analyses, and many of these affect the results. We provide recommendations based on reviewing the current evidence. Although the focus is on logistic regression, many of our results should be applicable to DIF analyses in general. There is a need for more empirical and theoretical work in this area.

Impact of cultural and linguistic factors on symptom reporting by patients with cancer

BACKGROUND

Patient reporting of the severity and impact of symptoms is an essential component of cancer symptom management and cancer treatment clinical trials. In multinational clinical trials, cultural and linguistic variations in patient-reported outcomes instruments could confound the interpretation of study results.

METHODS

The severity and interference of multiple symptoms in 1433 cancer patients with mixed diagnoses and treatment status from the United States, China, Japan, Russia, and Korea were measured with psychometrically validated language versions of the M. D. Anderson Symptom Inventory (MDASI). Mixed-effect ordinal probit regression models were fitted to the pooled data to compare the magnitude of the effect of "country" (nation and linguistic factors) with between-subjects effects on symptom reporting, adjusted for patient and clinical factors (age, sex, performance status, and chemotherapy status).

RESULTS

For the pooled sample, fatigue, disturbed sleep, distress, pain, and lack of appetite were the most severe patient-reported MDASI symptoms. The magnitude of the variance of the country random effects was only one-fourth to one-half of the interpatient variation (sigma(2) = 0.23-0.46) for all symptoms, except nausea and vomiting.

CONCLUSIONS

Cultural and linguistic variations in symptom reporting among the five language versions of the validated MDASI were limited. Ordinal probit modeling provided a simple mechanism for accounting for cultural and linguistic differences in patient populations. The equivalence among MDASI translations in this study suggests that symptom ratings collected from various cultural and language groups using the MDASI can be interpreted in a similar way in oncology practice, clinical trials, and clinical research.

Psychometric validation of the Manual Ability Measure-36 (MAM-36) in patients with neurologic and musculoskeletal disorders

OBJECTIVES

To evaluate the psychometric properties of the Manual Ability Measure-36 (MAM-36), a new hand function outcome measure, and to examine differences in manual abilities and item parameters in patients with neurologic and musculoskeletal conditions.

DESIGN

Convenience sample from 2 time periods, cross-sectional.

SETTING

Outpatient rehabilitation units and private hand clinics.

PARTICIPANTS

Patients (N=337; mean age, 50.3+/-14.9y) with a variety of neurologic and musculoskeletal (orthopedic) diagnoses. Most of these individuals were community dwelling, and all had residual functional limitations in the hand(s).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Rasch analysis was performed on MAM-36 data to evaluate both scale structure and psychometric properties, which include rating distribution, step measures, item fit, separation, and dimensionality. A t test was performed to examine the differences in manual abilities in patients with the 2 conditions. Uniform differential item functioning (DIF) between neurologic and musculoskeletal groups was examined. (DIF occurs when subgroup members within the sample with the same level of the underlying trait being measured respond differently to an individual item.) Manual ability estimates were recalibrated with step and common item anchoring; they were compared with those derived from the original analysis.

RESULTS

The 36 items measured a single construct with no misfitting items. The scale was used as intended. The items can reliably separate the participants into 5 ability strata. Neurologic patients had a significantly lower mean manual ability than musculoskeletal patients. Fourteen items exhibited DIF. However, DIF had no effect on either scale quality or calibration of manual ability. We decided that a single rating scale is appropriate for both groups.

CONCLUSIONS

This study showed that the MAM-36 has more than adequate psychometric properties and can be used as a generic outcome measure for patients with a wide variety of clinical diagnoses.

Differential item functioning was negligible in an adaptive test of functional status for patients with knee impairments who spoke English or Hebrew

OBJECTIVE

We examined the presence and impact of differential item functioning (DIF) in a set of knee-specific functional status (FS) items administered using computerized adaptive testing (CAT) among English (United States) and Hebrew (Israel) speaking patients receiving therapy for knee impairments. DIF occurs in an item if probabilities of endorsing responses differ across groups after controlling for the FS measured.

METHODS

We analyzed data from 28,320 patients (14,160 U.S., 14,160 Israel) who completed the knee-specific CAT. Items were assessed for DIF by gender, age, symptom acuity, surgical history, exercise history, and language spoken using a hybrid technique that combines multiple ordinal logistic regression and item response theory FS estimates.

RESULTS

Several items had non-uniform DIF for covariates including language, but unadjusted and DIF-adjusted functional status estimates were in strong concordance [ICC(2,1) values >/=0.97], and differences between unadjusted and adjusted FS scores represented <0.4% of the unadjusted FS standard deviation.

CONCLUSIONS

Statistically significant DIF was identified in some items but represented negligible clinical impact. Results suggested no need to adjust items for DIF when assessing FS outcomes across groups of patients with knee impairments who answer the knee CAT items in English in the United States or Hebrew in Israel. These findings suggest negligible differences in cultural perceptions between English and Hebrew wording of these knee-specific CAT FS items.

Developing core sets for patients with head and neck cancer based on the International Classification of Functioning, Disability and Health (ICF)

Problems in functioning are frequently seen in survivors of head and neck cancer (HNC) and proof to have increasing impact on their quality of life. With the approval of the International Classification of Functioning, Disability and Health (ICF) by the World Health Assembly in May 2001, we can now rely on a globally accepted framework and classification system based on a bio-psycho-social mode to assess and compare functional outcome. To make the ICF-classification with more than 1.400 categories applicable to every-day clinical practice, ICF core sets are established. The objective of this paper is to outline the proposed development process for the ICF core set for HNC and to invite international experts to participate in this process. The ICF core set will be defined at a Consensus conference, which will integrate evidence from preparatory studies, namely: (a) a systematic literature review regarding the outcome measures of clinical trails and observational studies, (b) semi-structured patient interviews, (c) international experts participating in a internet-based survey and (d) cross-sectional, multi-center studies for clinical applicability. To validate the ICF core set field-testing will follow. The ICF provides useful standards of clinical rehabilitation practice, research and teaching. Its application stimulates comparability of outcome parameters, eventually improving understanding of functioning and disability. The ICF can function as a new language, simplifying communication and cooperation between various professional backgrounds and between health professionals and their patients eventually leading to a more effective and economic rehabilitation. The ICF core set for HNC is designed to translate the benefits of the ICF into clinical routine. The development of ICF core sets is an inclusive and open process. Anyone who wishes to actively participate is invited to contact the project coordinator (Uta.Tschiesner@med.uni-muenchen.de). Individuals, institutions and associations can be formally associated as partners of the project.

A comparison of three sets of criteria for determining the presence of differential item functioning using ordinal logistic regression

BACKGROUND

Several techniques have been developed to detect differential item functioning (DIF), including ordinal logistic regression (OLR). This study compared different criteria for determining whether items have DIF using OLR.

OBJECTIVES

To compare and contrast findings from three different sets of criteria for detecting DIF using OLR. General distress and physical functioning items were evaluated for DIF related to five covariates: age, marital status, gender, race, and Hispanic origin.

RESEARCH DESIGN

Cross-sectional study.

SUBJECTS

1,714 patients with cancer or HIV/AIDS.

MEASURES

A total of 23 items addressing physical functioning and 15 items addressing general distress were selected from a pool of 154 items from four different health-related quality of life questionnaires.

RESULTS

The three sets of criteria produced qualitatively and quantitatively different results. Criteria based on statistical significance alone detected DIF in almost all the items, while alternative criteria based on magnitude detected DIF in far fewer items. Accounting for DIF by using demographic-group specific item parameters had negligible effects on individual scores, except for race.

CONCLUSIONS

Specific criteria chosen to determine whether items have DIF have an impact on the findings. Criteria based entirely on statistical significance may detect small differences that are clinically negligible.

Rapid detection of differential item functioning in assessments of health-related quality of life: The Functional Assessment of Cancer Therapy

REASON FOR STUDY

Differential item functioning (DIF) occurs when a test item functions differently in different groups when controlling for the level of the underlying construct measured by the test. DIF assessment is a first step in the evaluation of test bias. We sought to demonstrate a rapid hybrid approach to DIF detection by determining the presence and scale-level impact of DIF related to eight covariates in four domains measured by the Functional Assessment of Cancer Therapy (FACT).

MAJOR FINDINGS

The number of items found with DIF in each domain depended on the criterion chosen to define the presence of DIF. With a few exceptions, scale-level differential functioning was similar regardless of the criteria chosen. For physical well-being, there was relevant scale-level differential functioning related only to race. For social and family well-being, there was relevant scale-level differential functioning related to each of the covariates. For emotional well-being, there was relevant scale-level differential functioning related to ethnicity, language, and race. For functional well-being, there was relevant scale-level differential functioning related to ethnicity, race, education, and self- vs. interviewer-administration.

PRINCIPAL CONCLUSIONS

Our rapid hybrid approach to DIF detection may be broadly applicable in other studies of health-related quality of life.

Evaluating linguistic equivalence of patient-reported outcomes in a cancer clinical trial

BACKGROUND

In order to make meaningful cross-cultural or cross-linguistic comparisons of health-related quality of life (HRQL) or to pool international research data, it is essential to create unbiased measures that can detect clinically important differences. When HRQL scores differ between cultural/linguistic groups, it is important to determine whether this reflects real group differences, or is the result of systematic measurement variability.

PURPOSE

To investigate the linguistic measurement equivalence of a cancer-specific HRQL questionnaire, and to conduct a sensitivity analysis of treatment differences in HRQL in a clinical trial.

METHODS

Patients with newly diagnosed chronic myelogenous leukemia (n = 1049) completed serial HRQL assessments in an international Phase III trial. Two types of differential item functioning (uniform and non-uniform) were evaluated using item response theory and classical test theory approaches. A sensitivity analysis was conducted to compare HRQL between treatment arms using items without evidence of differential functioning.

RESULTS

Among 27 items, nine (33%) did not exhibit any evidence of differential functioning in both linguistic comparisons (English versus French, English versus German). Although 18 items functioned differently, there was no evidence of systematic bias. In a sensitivity analysis, adjustment for differential functioning affected the magnitude, but not the direction or interpretation of clinical trial treatment arm differences.

LIMITATIONS

Sufficient sample sizes were available for only three of the eight language groups. Identification of differential functioning in two-thirds of the items suggests that current psychometric methods may be too sensitive.

CONCLUSIONS

Enhanced methodologies are needed to differentiate trivial from substantive differential item functioning. Systematic variability in HRQL across different groups can be evaluated for its effect upon clinical trial results; a practice recommended when data are pooled across cultural or linguistic groups to make conclusions about treatment effects.

Comparing translations of the EORTC QLQ-C30 using differential item functioning analyses

The European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30 is one of the most widely used quality of life instruments for cancer patients. The aim of this study was to assess whether there were linguistic differences in the way an international sample answered the EORTC QLQ-C30 questionnaire. Thirteen translations of the EORTC QLQ-C30, representing 22 countries, were investigated using a database of 27,891 respondents, incorporating 103 separate studies. Differential item functioning (DIF) analyses were conducted using logistic regression to identify items which, after controlling for subscale, were answered differently by language of administration. Both uniform and non-uniform DIF were assessed. Although most languages showed similar results to English, at least one instance of statistically significant DIF was identified for each translation, and a few of these differences were large. In some cases, the patterns were supported by the results of qualitative interviews with bilingual people. Although, overall, there appeared to be good linguistic equivalence for most of the EORTC QLQ-C30 items, several scales showed strongly discrepant results for some translations. Some of these effects are large enough to impact on the results of clinical trials. Based on our experience in this study, we suggest that validation of translations of health-related quality of life instruments should include exploration of DIF.