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Purpose: Being able to function independently in society is an important aspect of quality of life. This ability goes beyond self-care, requires higher order cognitive functioning, and is typically measured with instrumental activities of daily living (IADL) questionnaires. Cognitive deficits are frequently observed in brain tumour patients, however, IADL is almost never assessed because no valid and reliable IADL measure is available for this patient group. Therefore, this measure is currently being developed., Methods: This international multicentre study followed European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Group module development guidelines. Three out of four phases are completed: phases (I) generation of items, (II) construction of the item list, and (III) pre-testing. This paper reports the item selection procedures and preliminary psychometric properties of the questionnaire. Brain tumour patients (gliomas and brain metastases), their informal caregivers, and health care professionals (HCPs) were included., Results: Phase I (n = 44 patient-proxy dyads and 26 HCPs) generated 59 relevant and important activities. In phase II, the activities were converted into items. In phase III (n = 85 dyads), the 59 items were pre-tested. Item selection procedures resulted in 32 items. Exploratory factor analysis revealed a preliminary dimensional structure consisting of five scales with acceptable to excellent internal consistency (α = 0.73-0.94) and two single items. For three scales, patients with cognitive impairments had significantly more IADL problems than patients without impairments., Conclusion: A phase IV validation study is needed to confirm the psychometric properties of the EORTC IADL-BN32 questionnaire in a larger international sample.

Background: The European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Group (QLG) has developed computerised adaptive tests (CATs) for the 14 functional and symptom domains of the EORTC QLQ-C30 quality of life questionnaire. This is expected to optimise measurement precision, relevance to patients and flexibility. Here, we present the first international validation of the EORTC CAT Core., Methods: A heterogeneous sample of 699 cancer patients scheduled for chemotherapy and/or radiotherapy was recruited across seven European countries. The EORTC CAT Core and all QLQ-C30 items were administered to participants before and after initiating treatment. Correlations between CAT and QLQ-C30 scores and floor/ceiling effects were calculated. Using several grouping variables, relative validity (cross-sectional known groups difference), responsiveness (changes over time) and relative sample size requirements of the CAT compared to the QLQ-C30 were estimated., Results: Correlations of the CAT and QLQ-C30 ranged from 0.81 to 0.93 across domains. The mean relative reduction in floor and ceiling effects using the CAT was 42% (range 3-99%). Analyses of known groups validity and responsiveness indicated that, across domains, mean sample size requirements for the CAT were 72% and 70%, respectively, of those using the QLQ-C30., Conclusions: The EORTC CAT Core measures the same domains as the QLQ-C30 with reduced floor/ceiling effects. The CAT generally facilitated the use of smaller samples (about 30% smaller on average) without loss of power compared to the QLQ-C30. Based on this study, the EORTC QLG will release the EORTC CAT Core for general use.

Purpose: To ensure that observed differences in the scores of the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30) reflect actual differences in health-related quality of life (HRQoL) rather than measurement bias, measurement invariance needs to be established. We investigated the assumption of measurement invariance of the EORTC QLQ-C30 in patients with hematological malignancies across age, sex, comorbidity, disease type, and time., Methods: We used a large database of patients with hematological malignancies, which included HRQoL data collected with the EORTC QLQ-C30. We used the structural equation modeling approach to test for measurement (metric and scalar) invariance across groups (age, sex, comorbidity, disease) and time (baseline, 1 month and 2 month follow-up). Longitudinal invariance was examined in a subgroup of patients diagnosed with myelodysplastic syndromes., Results: Confirmatory factor analyses demonstrated full measurement invariance for age and comorbidity and over time, while support for partial scalar invariance was obtained for sex and disease. Violations of invariance for sex were observed for items of the physical functioning scale and the emotional functioning scale, while for disease type, violations of invariance were observed for items of the physical functioning scale, emotional functioning scale, and the cognitive functioning scale., Conclusions: Our findings support measurement invariance of the EORTC QLQ-C30 in a large sample of patients with hematological malignancies. The results showed that the number of non-invariant items was negligible, suggesting that this questionnaire is a valid and robust measurement tool in patients with hematological malignancies, also for comparisons across groups and time.

Purpose: To investigate the scale structure and psychometrics of the EORTC chemotherapy-induced peripheral neuropathy module (QLQ-CIPN20)., Methods: Using confirmatory factor analyses (CFA), we tested two hypothesized scale structure models of the QLQ-CIPN20 in 473 patients with non-small cell lung cancer, 281 patients with heterogeneous cancer diagnoses, and 500 patients with colorectal cancer. We also modeled the two hypothesized models as bi-factor models. These included a general factor, in addition to the specific domain factors. Additional models were investigated with exploratory factor analysis (EFA). Known groups validity was evaluated where justified., Results: CFA could not confirm the two hypothesized models (Model 1: CFI < 0.926; TLI < 0.914; RMSEA > 0.077 and Model 2: CFI < 0.906; TLI < 0.887; RMSEA > 0.105) in any of the three samples. Including a general factor to these two hypothesized models to produce a bi-factor model also did not yield satisfactory results. Using EFA, we identified four different factor structures in the three samples that were unstable due to cross loadings of the items. When scoring the QLQ-CIPN20 as a simple, additive checklist evidence was found for known groups validity in the first two samples based on Common Toxicity Criteria (CTC-AE), and in the third sample based on exposure to CIPN-inducing chemotherapy., Conclusions: Neither CFA nor EFA yielded support for a stable subscale structure for the QLQ-CIPN20. Scoring the questionnaire as a simple additive checklist results in acceptable validity.

Purpose: Clinical trials in glioma patients with neurocognitive deficits face challenges due to lacking or unreliable patient self-reports on their health-related quality of life (HRQOL). Patient-proxy data could help solve this issue. We determined whether patient-proxy concordance levels were affected by patients' neurocognitive functioning., Methods: Patient and patient-by-proxy HRQOL ratings were assessed via SF-36 and EORTC QLQ-BN20, respectively, in 246 patients. Data on neurocognitive functioning were collected on a subgroup of 195 patients. Patient-proxy agreement was measured using the Bland-Altman limit of agreement, the mean difference, the concordance correlation coefficient (CCC), and the percentage difference (PD, ±0, 5, or 10 points). We defined patients to be cognitively impaired (n = 66) or cognitively intact (n = 129) based on their neurocognitive performance., Results: Patients rated their physical function and general health to be better than their proxies did, while at the same time, patients reported more visual disorders, communication deficits, itchy skin, and problems with bladder control. The cognitively impaired subgroup reported poorer physical functioning, more visual disorders, headaches, itchy skin, and issues with bladder control. In the cognitively intact group, no statistical significant differences were observed between patients and proxies. Not surprisingly, Bland-Altman plots revealed a high agreement between the patient and patient-by-proxy rating in all HRQOL domains ranging from 95 to 99 %. The CCC was fairly high in all HRQOL domains (0.37-0.80), and the percentage of perfect agreement (PD ± 0) ranged from 8.5 to 76.8 %. In the cognitively impaired patients, the mean difference between patients and proxies was overall larger, and accordingly, agreement based on Bland-Altman plots was lower., Conclusions: The level of agreement between patient and patient-by-proxy ratings of low-grade glioma patients' HRQOL is generally high. However, patient-proxy agreement is lower in patients with neurocognitive deficits than in patients without neurocognitive deficits.

Purpose: Patient-reported outcomes should ideally be adapted to the individual patient while maintaining comparability of scores across patients. This is achievable using computerized adaptive testing (CAT). The aim here was to develop an item bank for CAT measurement of the pain domain as measured by the EORTC QLQ-C30 questionnaire., Methods: The development process consisted of four steps: (1) literature search, (2) formulation of new items and expert evaluations, (3) pretesting and (4) field-testing and psychometric analyses for the final selection of items., Results: In step 1, we identified 337 pain items from the literature. Twenty-nine new items fitting the QLQ-C30 item style were formulated in step 2 that were reduced to 26 items by expert evaluations. Based on interviews with 31 patients from Denmark, France and the UK, the list was further reduced to 21 items in step 3. In phase 4, responses were obtained from 1103 cancer patients from five countries. Psychometric evaluations showed that 16 items could be retained in a unidimensional item bank. Evaluations indicated that use of the CAT measure may reduce sample size requirements with 15-25% compared to using the QLQ-C30 pain scale., Conclusions: We have established an item bank of 16 items suitable for CAT measurement of pain. While being backward compatible with the QLQ-C30, the new item bank will significantly improve measurement precision of pain. We recommend initiating CAT measurement by screening for pain using the two original QLQ-C30 pain items. The EORTC pain CAT is currently available for "experimental" purposes.

Purpose: The objective of this study was to evaluate the measurement equivalence of an interactive voice response system (IVRS) version and the original paper-based version of the EORTC QLQ-C30., Methods: The QLQ-C30 is a cancer-specific, health-related quality of life questionnaire consisting of nine multi-item scales (physical, role, emotional, cognitive and social functioning, fatigue, nausea/vomiting, pain, and quality of life) and six single item measures (dyspnea, insomnia, appetite loss, constipation, diarrhea, and financial problems). This study utilized a crossover design with subjects randomly assigned to one of two assessment orders: (1) paper then IVRS or (2) IVRS then paper. Equivalence between the two administration modes was established by comparing the 95% lower confidence interval (CI) of the intraclass correlation coefficients (ICCs) for each scale, with a critical value of 0.70., Results: The ICCs for the nine multi-item scales were all above 0.79, ranging from 0.791 to 0.899 (ICC 95% lower CI range 0.726-0.865) and significantly different from our threshold reliability of 0.70. The ICCs for the six single items ranged from 0.689 to 0.896 (ICC 95% lower CI range 0.611-0.888). Two of the items, insomnia and appetite loss, were not statistically different from 0.70. When considered together, the per-protocol analysis results support the equivalence of the paper and IVRS versions of the QLQ-C30 for 13 of the 15 scores., Conclusion: This analysis provides evidence that the scores obtained from the IVRS version of the QLQ-C30 are equivalent to those obtained with the original paper version except for the insomnia and appetite loss items.

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.

Objective: This report extracts important considerations for determining and applying clinically significant differences in quality of life (QOL) measures from six published articles written by 30 international experts, in the field of QOL assessment and evaluation. The original six articles were presented at the Symposium on Clinical Significance of Quality of Life Measures in Cancer Patients at the Mayo Clinic in April 2002 and subsequently were published in Mayo Clinic Proceedings., Principal Findings: Specific examples and formulas are given for anchor-based methods, as well as distribution-based methods that correspond to known or relevant anchors to determine important differences in QOL measures. Important prerequisites for clinical significance associated with instrument selection, responsiveness, and the reporting of QOL trial results are provided. We also discuss estimating the number needed to treat (NNT) relative to clinically significant thresholds. Finally, we provide a rationale for applying group-derived standards to individual assessments., Conclusions: While no single method for determining clinical significance is unilaterally endorsed, the investigation and full reporting of multiple methods for establishing clinically significant change levels for a QOL measure, and greater direct involvement of clinicians in clinical significance studies are strongly encouraged.

Context: Few studies and no international comparisons have examined the impact of multiple chronic conditions on populations using a comprehensive health-related quality of life (HRQL) questionnaire., Objective: The impact of common chronic conditions on HRQL among the general populations of eight countries was assessed., Design: Cross-sectional mail and interview surveys were conducted., Participants and Setting: Sample representatives of the adult general population of eight countries (Denmark, France, Germany, Italy, Japan, The Netherlands, Norway and the United States) were evaluated. Sample sizes ranged from 2031 to 4084., Main Outcome Measures: Self-reported prevalence of chronic conditions (including allergies, arthritis, congestive heart failure, chronic lung disease, hypertension, diabetes, and ischemic heart disease), sociodemographic data and the SF-36 Health Survey were obtained. The SF-36 scale and summary scores were estimated for individuals with and without selected chronic conditions and compared across countries using multivariate linear regression analyses. Adjustments were made for age, gender, marital status, education and the mode of SF-36 administration., Results: More than half (55.1%) of the pooled sample reported at least one chronic condition, and 30.2% had more than one. Hypertension, allergies and arthritis were the most frequently reported conditions. The effect of ischemic heart disease on many of the physical health scales was noteworthy, as was the impact of diabetes on general health, or arthritis on bodily pain scale scores. Arthritis, chronic lung disease and congestive heart failure were the conditions with a higher impact on SF-36 physical summary score, whereas for hypertension and allergies, HRQL impact was low (comparing with a typical person without chronic conditions, deviation scores were around -4 points for the first group and -1 for the second). Differences between chronic conditions in terms of their impact on SF-36 mental summary score were low (deviation scores ranged between -1 and -2)., Conclusions: Arthritis has the highest HRQL impact in the general population of the countries studied due to the combination of a high deviation score on physical scales and a high frequency. Impact of chronic conditions on HRQL was similar roughly across countries, despite important variation in prevalence. The use of HRQL measures such as the SF-36 should be useful to better characterize the global burden of disease.

In cross-national comparisons based on questionnaires, accurate translations are necessary to obtain valid results. Differential item functioning (DIF) analysis can be used to test whether translations of items in multi-item scales are equivalent to the original. In data from 10,815 respondents representing 10 European languages we tested for DIF in the nine translations of the EORTC QLQ-C30 emotional function scale when compared to the original English version. We tested for DIF using two different methods in parallel, a contingency table method and logistic regression. The DIF results obtained with the two methods were similar. We found indications of DIF in seven of the nine translations. At least two of the DIF findings seem to reflect linguistic problems in the translation. 'Imperfect' translations can affect conclusions drawn from cross-national comparisons. Given that translations can never be identical to the original we discuss how findings of DIF can be interpreted and discuss the difference between linguistic DIF and DIF caused by confounding, cross-cultural differences, or DIF in other items in the scale. We conclude that testing for DIF is a useful way to validate questionnaire translations.

The field of health status and quality of life (QoL) measurement - as a formal discipline with a cohesive theoretical framework, accepted methods, and diverse applications--has been evolving for the better part of 30 years. To identify health status and QoL instruments and review them against rigorous criteria as a precursor to creating an instrument library for later dissemination, the Medical Outcomes Trust in 1994 created an independently functioning Scientific Advisory Committee (SAC). In the mid-1990s, the SAC defined a set of attributes and criteria to carry out instrument assessments; 5 years later, it updated and revised these materials to take account of the expanding theories and technologies upon which such instruments were being developed. This paper offers the SAC's current conceptualization of eight key attributes of health status and QoL instruments (i.e., conceptual and measurement model; reliability; validity; responsiveness; interpretability; respondent and administrative burden; alternate forms; and cultural and language adaptations) and the criteria by which instruments would be reviewed on each of those attributes. These are suggested guidelines for the field to consider and debate; as measurement techniques become both more familiar and more sophisticated, we expect that experts will wish to update and refine these criteria accordingly.