Validating and Improving the Reliability of the EORTC QLQ-C30 Using a Multidimensional Rasch Model

ObjectiveThe reliability and validity of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30) has not been examined while taking into account the correlation between subscales. The reliability of the EORTC QLQ-C30 subscales is modest, thus limiting their utility in both clinical and research settings. The purpose of this study was to validate the factor structure of multiple-item subscales of the EORTC QLQ-C30 and to improve their reliability by means of an item response analysis by using the multidimensional partial credit model.MethodsA total of 2295 patients with complete data were used for the analysis. One- and nine-dimensional partial credit models were used to fit the data to validate the construct validity of the multiple-item subscales of the QLQ-C30.ResultsThe model comparison showed that the nine-dimensional factor structure of multiple-item subscales was satisfactory. The multidimensional partial credit model fit data of the multiple-item subscales of the QLQ-C30 reasonably well. The estimated test reliabilities of each domain obtained from the multidimensional approach were higher than those obtained from the unidimensional approach.ConclusionsThe constructs represented by the multiple-item subscales of the QLQ-C30 were validated. The improved reliability of the multiple-item subscales of the QLQ-C30 under the multidimensional approach can facilitate their applications in clinical and research settings.     

The interpretation of scores from the EORTC quality of life questionnaire QLQ-C30

While quality of life (QOL) assessment is becoming more common, interpreting the results remains problematic. This paper demonstrates an approach to developing clinically-based interpretations for QOL outcomes, using the QLQ-C30 as an example. The results from 14 published QLQ-C30 studies which group patients by performance status, weight loss, toxicity, extent or severity of disease are collated. Groups with lower clinical status generally have worse QOL. The largest differences are between performance status groups, and the smallest differences are between groups of patients with local disease and those with metastases. The physical and role scores have the largest ranges of means across patient groups, and show the largest differences between clinical groups, while the cognitive and emotional scores have the smallest ranges of means and differences. Sicker groups have larger score standard deviations than healthie groups. Relatively large and small means and differences, and corresponding effect sizes, are presented. Collectively, the results provide a sense of the relative sizes of means and of differences, and of the types of clinical groups which give rise to them, thereby providing clinically-based benchmarks by which to interpret QLQ-C30 results.     

The use of differential item functioning analyses to identify cultural differences in responses to the EORTC QLQ-C30

Introduction The European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30 is a widely used health-related quality of life instrument. The main aim of this study is to investigate whether there are international differences in response to the questionnaire that can be explained by cultural factors. Methods Analyses involved a database of 106 separate studies including data from over 28,000 respondents. Differential item functioning (DIF) analyses using logistic regression were conducted for each item of the EORTC QLQ-C30 with respect to cultural/geographic group. Results were qualitatively compared with previously reported DIF analyses by translation to explore whether the source of the DIF was more likely to be linguistic or cultural in nature. Results Although most response patterns were similar, there were a number of international differences in how the questionnaire was answered. The largest variations were found in the results for Eastern Europe and East Asia. Results for the UK, the US and Australia tended to be similar. Many of the European results followed patterns that were more clearly explained when grouped by translation than when grouped by geographical region. Discussion Our results suggest that, in general, the EORTC QLQ-C30 is suitable for use in a wide variety of countries and settings. Some response variations that have the potential to affect the results of international studies were identified, but it was not always clear whether the source of the variation was primarily linguistic or cultural.     

Multidimensional Computerized Adaptive Testing of the EORTC QLQ-C30: Basic Developments and Evaluations

Objective: Self-report questionnaires are widely used to measure health-related quality of life (HRQOL). Ideally, such questionnaires should be adapted to the individual patient and at the same time scores should be directly comparable across patients. This may be achieved using computerized adaptive testing (CAT). Usually, CAT is carried out for a single domain at a time. However, many HRQOL domains are highly correlated. Multidimensional CAT may utilize these correlations to improve measurement efficiency. We investigated the possible advantages and difficulties of multidimensional CAT. Study design and setting: We evaluated multidimensional CAT of three scales from the EORTC QLQ-C30: the physical functioning, emotional functioning, and fatigue scales. Analyses utilised a database with 2958 European cancer patients.Results: It was possible to obtain scores for the three domains with five to seven items administered using multidimensional CAT that were very close to the scores obtained using all 12 items and with no or little loss of measurement precision.Conclusion: The findings suggest that multidimensional CAT may significantly improve measurement precision and efficiency and encourage further research into multidimensional CAT. Particularly, the estimation of the model underlying the multidimensional CAT and the conceptual aspects need further investigations.     

Translation and validation of the Standard Chinese version of the EORTC QLQ-C30

The majority of quality of life (QOL) questionnaires have been developed and used in English-speaking or Western European countries. The aims of this study were to provide the Standard Chinese version of the European Organization for Research and Treatment of Cancer Quality of Life Core Questionnaire (EORTC QLQ-C30 version 2.0), and evaluate its psychometric properties. The translation process included independent translation, back translation, a pilot test with gynecological cancer patients, and a review and approval by the original developers. Participants in the major study included gestational trophoblastic disease patients (n = 68), ovarian cancer patients (n = 105), and other types of gynecological cancer patients (n = 18). The average completion time of the Standard Chinese version was 8.1 ± 2.9 min. All item-subscale correlation coefficients exceeded the criterion of item-convergent validity (r > 0.40) except item 1, 5, 20, and 25, and all items correlated significantly higher with their own subscale than with other subscales except item 1, 20, and 25. The correlation coefficients among all subscales were significant but modest (r = 0.40–0.70). Seven out of nine subscales met the minimal standards of reliability (Cronbach's > 0.70). In conclusion, the Standard Chinese version of the EORTC QLQ-C30 is a valid instrument overall in assessing the QOL of Chinese gynecological cancer patients.     

Two Kinds of Items in Quality of Life Instruments: ‘Indicator and Causal Variables’ in the EORTC QLQ-C30

Two kinds of variables may be differentiated within instruments measuring health-related quality of life (HRQOL). Physical symptoms may be called causal variables because their occurrence can cause a change in HRQOL, but poor HRQOL need not necessarily imply that a patient suffers from these symptoms. Other items can be regarded as indicator variables. They reflect the level of HRQOL and a patient with a poor HRQOL is likely to have low scores on all indicator variables. The aim of this study was to test the relationship of the latent HRQOL construct to items and domains on the EORTC QLQ-C30. Confirmatory factor analysis was performed on EORTC QLQ-C30 data from 205 gastrointestinal cancer patients assessed one month after surgery. Functioning scales were established as variables indicating the level of HRQOL whereas all other subscales and items were established as variables causing a change in HRQOL. The model-data fit was satisfactory. Results support the hypothesis that two kinds of variables may be differentiated within HRQOL instruments. Further research should investigate whether both kinds of variables could be combined into a higher order, aggregate score for HRQOL.     

The relationship of changes in EORTC QLQ-C30 scores to ratings on the Subjective Significance Questionnaire in men with localized prostate cancer

PURPOSE: To examine the relationship between changes in health-related quality-of-life (HRQOL) on the EORTC Quality of Life Questionnaire (QLQ-C30), and patients' perceptions of HRQOL changes as measured by the Subjective Significance Questionnaire (SSQ). PATIENTS AND METHODS: A total of 101 patients completed the QLQ-C30 on weeks 1, 4 and 7 of radical external-beam radiation therapy (RT) for localized cancer of the prostate. Patients rated their change in physical functioning, emotional functioning, social functioning, and overall/global quality of life (QOL) by completing a seven-category SSQ at weeks 4 and 7. The association between changes in the QLQ-C30 change and the corresponding SSQ ratings were determined by calculation of mean change scores for each SSQ category and by Spearman rank correlation coefficient analysis. RESULTS: Patients' completion of the QLQ-C30 and SSQ exceeded 95%. Statistically significant changes in fatigue, pain, appetite, diarrhea, and global QOL scores were detected during RT. For patients reporting 'a little' change in global QOL on the SSQ, absolute mean QLQ-C30 change scores ranged between 0 to 15 points with 12/16 mean change scores between 2.5 and 8.5 points. In the entire study sample, correlations between SSQ patient ratings and QLQ-C30 change scores were lower than previously reported, ranging between 0.15 and 0.24 for the four different domains, but were higher when QOL scores producing ceiling effects were omitted. CONCLUSION: The SSQ and QLQ-C30 may measure related concepts that could assist in the interpretation of changes in scores and in the calibration of the QLQ-C30. However, the nature of this relationship could not be elucidated in this data set because of a lack of variance in HRQOL scores in the study sample. Further investigation should be carried out in study samples with sufficient variance to allow more robust conclusions.     

Quality of life in cancer patients in South Asia: psychometric properties of the Sinhala version of the EORTC QLQ-C30 in cancer patients with heterogeneous diagnoses

BACKGROUND: The European Organisation for Research and Treatment of Cancer Quality of Life Core Questionnaire (EORTC QLQ-C30) was evaluated for its psychometric properties in a sample of cancer patients from the culturally distinct South Asian subcontinent, which accounts for a significant proportion of the global cancer burden. METHODS: Psychometric testing assessed the hypothesised scale structure, internal consistency, content and construct validity, and acceptability of the Sinhala version of the QLQ-C30 independently in two heterogeneous groups of cancer patients at pretreatment (N = 489) and during treatment (N = 343). RESULTS: Qualitative feedback from an expert panel assessing content validity recommended measuring family support during illness as an additional, culturally-relevant dimension of health-related quality of life (HRQL). Compliance was high (100%), with little missing data (0.11%). Multitrait scaling results supported the scale structure of the QLQ-C30, with the exception of the cognitive functioning scale, which was also the only scale that did not meet the 0.70 internal consistency criteria in either sample. Interscale correlations were of a moderate size, with conceptually related scales showing higher correlations. All scales were able to discriminate clearly between pre- and current treatment patients (P < 0.01), although results were less consistent when comparing groups formed on the basis of age and disease stage. CONCLUSIONS: Overall psychometric results confirmed the QLQ-C30 as a reliable and valid questionnaire for assessing HRQL of cancer patients in Sri Lanka.     

Mapping FACT-P and EORTC QLQ-C30 to Patient Health Status Measured by EQ-5D in Metastatic Hormone-Refractory Prostate Cancer Patients

OBJECTIVES: To construct and validate a prediction model of preference-adjusted health status (EQ-5D) for metastatic hormone-refractory prostate cancer (HRPCA) patients using cancer-specific health-related quality of life (HRQoL) measures. METHODS: Data were obtained from a multicenter, multinational observational study of metastatic HRPCA patients conducted during 2002 to 2004. In addition to clinical and resource utilization, preference-adjusted health status (EQ-5D) and HRQoL (Functional Assessment of Cancer Therapy-Prostate [FACT-P] and European Organization for Research and Treatment of Cancer Quality of Life Questionnaire [EORTC QLQ-C30]) data were collected. Predictive validity of ordinary least square (OLS) and median regressions of various model specifications were tested using cross-validation samples. The selected specification was then further refined and tested for alternative model specifications and restrictions. RESULTS: OLS regression with both HRQoL measures as individual components and patient demographics was the best-performing model. It explained 58.2% of the observed EQ-5D variation in the validation sample. A model including only the prostate cancer-specific HRQoL measure, FACT-P, explained 53.5% of the observed EQ-5D variation. CONCLUSIONS: The models developed have good predictive validity. These algorithms enable researchers to translate cancer-specific HRQoL measures to preference-adjusted health status in metastatic HRPCA patients. The findings will help perform health status adjustments in cost-utility analyses.     

Quality of life in patients of nasopharyngeal carcinoma: Validation of the Taiwan Chinese version of the EORTC QLQ-C30 and the EORTC QLQ-H&N35

The authors followed the guidelines of translation and pilot testing of the EORTC QLQ-C30 and EORTC-QLQ-H&N35 questionnaires. The questionnaires were given to 50 nasopharyngeal carcinoma patients under active treatment and 50 under follow-up at our institution from November 2000 to June 2001. A retest was conducted 2 weeks after the first interview/form completion for the follow-up group. The intraclass correlation coefficients of the two questionnaires were moderate to high in the follow-up group. Cronbach's coefficients of all scales of the two questionnaires were 0.70 except that of cognitive functioning. Correlation of scales measuring similar dimensions of the QLQ-C30 and the SF-36 were moderate to high, while that of the QLQ-H&N35 and the QLQ-C30 and the SF-36 were moderate to low. Patients in the active treatment group had more serious acute problems due to disease and chemotherapy. Patients in the follow-up group had more serious chronic problems due to radiation therapy. We concluded that the Taiwan Chinese version of the EORTC QLQ-C30 and the EORTC QLQ-H&N35 had moderate to high test–retest reliability, high internal consistency in most scales, and could show the expected differences between patients in active treatment and follow-up group.     

Measurement of quality of life in women with breast cancer. Development of a Life Satisfaction Questionnaire (LSQ-32) and a comparison with the EORTC QLQ-C30

The purpose was to develop and validate a new instrument suitable for measuring perceived quality of life in women with breast cancer. The instrument is to be used within conventional cancer therapy as well as in complementary care, and is called the LSQ-32 (Life Satisfaction Questionnaire). The subjects were 362 women with breast cancer in all cancer stages. Cronbach's reliability coefficient of the LSQ was 0.89. The construct validity was estimated by a principal component analysis. Six orthogonal factors were identified: (1) Quality of family relation, (2) Physical symptoms, (3) Socioeconomic situation, (4) Quality of daily activities, (5) Sickness impact and (6) Quality of close friend relation. The criterion-related validity was estimated by comparing the LSQ-32 and the EORTC QLQ-C30. The scales/items of the EORTC QLQ-C30 were represented in the LSQ-32, but the factors Quality of family relation and Quality of close friend relation were not found in the EORTC QLQ-C30. It was concluded that the LSQ-32 as well as the EORTC QLQ-C30 are valuable tools in the measurement of quality of life in women with breast cancer. The LSQ-32, however, also contains an existential factor.The study was approved on 1992 04 08 by the Research Ethical Committee, Faculty of Health Sciences, University of Linköping.     

Psychometric properties and responsiveness of the EORTC Quality of Life Questionnaire (QLQ-C30) in patients with breast,ovarian and lung cancer

The QLQ-C30, a health-related quality of life questionnaire developed for use in patients with cancer, has been previously validated in patients with lung cancer and head and neck cancer. In this study, further validation was carried out for 535 patients, including patients with breast cancer (n=143) and ovarian cancer (n=111) for whom there is no previously published validation, as well as patients with lung cancer (n=121). All patients were entered in one of two trials of anti-emetics to prevent chemotherapy-induced emesis. The QLQ-C30 was completed before chemotherapy and on day 8 after chemotherapy. The factor structure in patients with breast and ovarian cancer was similar to that previously described. Interdomain correlations, in the entire group, were strongest for the physical and role function domains and the fatigue, pain and global quality of life.domains before and after chemotherapy. In addition, after chemotherapy, social function was also strongly correlated with fatigue and global quality of life. These correlations were not always of equal strength in the breast, ovarian and lung groups, suggesting that there may be differences between these groups. The responsiveness of the QLQ-C30 in the presence of widely metastatic, as compared with locoregional, disease showed changes in the expected directions (i.e., diminished function in physical and social role functions and in global quality of life, with greater fatigue and pain in patients with metastatic disease). Eight days after chemotherapy, decreases were seen in physical, role and social functioning and in global quality of life, and there was greater fatigue, nausea and vomiting compared with before chemotherapy. Patients with breast cancer had better physical, role and social functioning, and less fatigue and pain than patients with ovarian cancer. This result is expected, since many of the patients with breast cancer had early stage disease, whereas those with ovarian cancer had advanced stage disease. Mean scores for patients with lung cancer were between the other two groups, in keeping with the mixture of early and advanced stage disease in these patients. There was a strong correlation between ECOG performance status scores and several domains of the QLQ-C30; these were all in the expected directions. The results of this study confirm those in earlier studies on patients with lung cancer, and provide new information on patients with breast and ovarian cancer. In addition, the QLQ-C30 is responsive to the effects of chemotherapy and of metastatic disease.     

Modification of the EORTC QLQ-C30 (version 2.0) based on content validity and reliability testing in large samples of patients with cancer

A revision of the Quality of Life Questionnaire (QLQ-C30) of the European Organization for Research and Treatment of Cancer (EORTC) was undertaken to improve low internal consistency estimates (Cronbach's alpha) and content validity for the role functioning scale and a conceptual difficulty (undue emphasis on physical functioning) in the global quality of life (QOL) scale. The role functioning items were reworded and a four-category response format was substituted for the previous dichotomous format. A new item asking about overall health was substituted for the overall physical condition item in the global QOL domain. The original and new versions were tested at three time points in a total of 1,181 patients with cancer in Canada (n=696) and the Netherlands (n=485). In both samples there was a marked improvement in internal consistency for the role functioning scale (Cronbach's alphas ranging from 0.78-0.88) in the new version. In the global QOL scale, the substitution of the new item for the previous one did not alter internal consistency (Cronbach's alphas ranging from 0.81-0.92). The revised versions of the role functioning and global QOL domains have been incorporated into the QLQ-C30 (version 2.0).     

Factor analysis of the psychosocial items of the EORTC QLQ-C30 in metastatic breast cancer patients participating in a psychosocial intervention study

The underlying factor structure of a subset of 12 items, which comprise the psychosocial subscales of the EORTC QLQ-C30 was explored in a group of women, all with metastatic breast cancer who were participating in a psychosocial intervention study. Two main factors were identified in this exploratory factor analysis, representing emotional distress and functional ability dimensions. A preliminary assessment of the external validity of the two factor structure was undertaken. The results support the validity of a summative emotional distress and functional ability score in this sample of patients. The functional ability score discriminated well for subgroups defined by clinical status indicators (e.g., performance status, pain, chemotherapy treatment, fatigue). The emotional distress subscale discriminated with respect to suffering, fatigue and sleep disturbance. Both subscales converged with related concepts measured by independent instruments, providing support for convergent validity. Summative index scores may be advantageous for application in particular research situations; applying quality adjustments in health policy analyses; for screening purposes; to monitor populations and make comparisons across broad groups and as stratification variables in clinical trials. Further research to confirm the 2 factor structure is required in other samples before the interpretation can be accepted with confidence.     

Quality of life of lung cancer patients: Validation of the Taiwan Chinese version of the EORTC QLQ-C30 and QLQ-LC13

The purpose of this study was to test the validity and reliability of the Taiwan Chinese translation of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core-30 (EORTC QLQ-C30, version 3) and Quality of Life Questionnaire Lung Cancer-13 (QLQ-LC13) questionnaires. Consecutively 51 patients with lung cancer undergoing active chemotherapy and 48 such patients undergoing regular follow-up completed the questionnaires. The intraclass correlation between test and retest ranged from 0.46 to 0.85 for the QLQ-C30 and was 0.76 for dyspnea for the QLQ-LC13. The kappa coefficients between test and retest ranged from 0.51 to 0.73 for single items of the QLQ-C30 and 0.49-0.68 for five of the nine items in the QLQ-LC13. The Cronbach's alpha coefficients were > or = 0.70 for all scales of the two questionnaires apart from that of cognitive functioning. The correlation coefficients between indices measuring similar dimensions of the EORTC QLQ-C30 and the SF-36 questionnaires ranged from 0.43 to 0.73, and that between the dyspnea scales of the two EORTC questionnaires was 0.70. Patients in the follow-up group revealed higher scores of global status/quality of life, and lower scores of nausea/vomiting, as also physical functioning. The questionnaires could also detect expected adverse effects of radiotherapy, cisplatin, and paclitaxel.     

Criterion-based validation of the EORTC QLQ-C36 in advanced melanoma: The CIPS questionnaire and proxy raters

An extensive quality of life (QOL) investigation of the effects of chemotherapy in patients with generalized malignant melanoma included a validation study of involved questionnaires. The QOL domains of the three basic quality of life questionnaires, the EORTC QLQ-C36 (European Organization for Research and Treatment of Cancer Quality of Life Core Questionnaire), a study-specific malignant melanoma (MM) module and the Hospital Anxiety and Depression (HAD) scale vs. the Cancer Inventory of Problem Situations (CIPS) were validated by correlation analyses. The value of using attending nurses and/or next of kin to assess the patients' situation was also examined. Functional and symptom scales of the C36 and the subscales of the HAD showed appropriate convergent and discriminant validity when compared with the CIPS. The subscales of the MM module had less clear relationships, probably due to lack of accordance in the CIPS. Assessments of attending nurses revealed very low correlations with the patients' measures. They under-estimated significantly series of specific symptoms and overestimated nausea and the overall quality of life of the patients. However, assessments of close relatives, mostly spouses, showed moderate to high correlations and no significant difference. These results further strengthen the overall validity of the modular approach of the EORTC QLQ technique. In this context of active chemotherapy in patients with advanced cancer disease, relatives seem to be better surrogates than the attending nurses in assessing the patients' quality of life.This study was made possible by grants from the King Gustav V Jubilee Fund, Stockholm, the Medical Faculty, University of Göteborg, Göteborg, Sweden and the Icelandic Cancer Society, Reykjavík, Iceland.     

Validity,reliability and clinical relevance of EORTC QLQ-C30 and LC13 in patients with chest malignancies in a palliative setting

Aims To evaluate the reliability and validity of the European Organization for Research and Treatment of Cancer (EORTC) QLQ-C30 and LC13 questionnaire in a palliative setting, and to undertake a broad clinical evaluation of the questionnaire. Patients One hundred and twelve patients with advanced lung cancer or pleural mesothelioma, not amenable to curative or life-prolonging treatment, were consecutively included. Methods Construct validity and reliability of the EORTC questionnaire were examined by multitrait analysis and internal consistency. Criterion validity was examined by variance by and correlation with an array of clinical measures, including tumour stage, performance status, 6-min walk test, spirometry, and blood tests. Concurrent validity was evaluated by established scales for emotional distress and pain. Results With the exception of cognitive functioning, reliability and construct validity of the QLQ-C30 was confirmed. Criterion and concurrent validity was supported for most of the functioning and symptom scales. In a multivariate stepwise regression analysis, EORTC physical functioning was predicted by performance status and 6-min walk distance (r ² = .70), emotional functioning by HADS anxiety ratings (r ² = .59), and global quality of life by performance status, HADS depression ratings, and FEV1 %predicted (r ² = .50). Conclusion The results support the validity and clinical relevance and of the EORTC questionnaire in a palliative setting.     

The European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30): Validation of English version in Singapore

Objective: This study aimed to validate the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30, English version 3.0) in Singaporean cancer patients. Methods: In a cross-sectional study, a heterogeneous sample of cancer patients (n = 57) self-administered a questionnaire containing the QLQ-C30, the Short Form 36 Health Survey (SF-36) and assessing health and sociodemographic status. Construct validity was assessed by testing a priori hypotheses that QLQ-C30 scales would be moderately or strongly correlated with SF-36 scales measuring similar dimensions of health-related quality of life (HRQoL) and that subjects reporting mild symptoms would have better HRQoL scores than those reporting severe symptoms. Internal consistency reliability was assessed using Cronbachs . Results: Strength of Spearmans correlations between the QLQ-C30 and SF-36 scales assessing similar dimensions of HRQoL ranged from 0.35 to 0.67. Subjects with mild symptoms had better scores than those with severe symptoms for all six QLQ-C30 HRQoL scales (p < 0.05 for five scales, Mann–Whitney U tests). Cronbachs ranged from 0.19 for the cognitive functioning scale to 0.91 for the global QoL scale. Conclusion: This study provides preliminary evidence for the validity and reliability of the EORTC QLQ-C30 in English-speaking Singaporean cancer patients.     

The OVIS study: health related quality of life measured by the EORTC QLQ-C30 and -BR23 in German female patients with breast cancer from Schleswig-Holstein

The OVIS study is a population-based study that aims at evaluating medical care in Schleswig-Holstein (Germany). In this paper, the health related quality of life (QoL, EORTC QLQ-C30 and -BR23) of 1,927 women with breast cancer is reported. The global health status/QoL score was comparable to reference data of the age-adjusted German general population, but clinical meaningful differences (≥ 10 points) were found for all functioning scales (with the exception of physical functioning) and for three of the symptom scales/items (fatigue, dyspnoe, insomnia) with OVIS patients showing more deficits. Furthermore, OVIS patients scored higher on the item financial difficulties. Logistic regression analyses revealed that coming from an urban surrounding, having a higher social status and attendance to a regular aftercare predicted a good overall QoL, while factors that were related to perceived complications in the course of the therapy raised the risk for a low QoL rating. It is of interest, that attendance to a rehabilitation and interest in self-help groups independently predicted an increased risk for a low quality of life. Overall, we assume the global QoL is rating slightly too optimistic since major deficits were reported on the specific physical and functional scales/items.