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Cocks K, King MT, Velikova G, Martyn St-James M, Fayers PM, Brown JM. Evidence-Based Guidelines for Determination of Sample Size and Interpretation of the European Organisation for the Research and Treatment of Cancer Quality of Life Questionnaire Core 30. J Clin Oncol 2011; 29:89-96. [PMID: 21098316 DOI: 10.1200/jco.2010.28.0107] [Citation(s) in RCA: 461] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Purpose To use published literature to estimate large, medium, and small differences in quality of life (QOL) data from the European Organisation for the Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30). Methods An innovative method combining systematic review of published studies, expert opinions, and meta-analysis was used to estimate large, medium, and small differences for QLQ-C30 scores. Published mean data were identified from the literature. Differences (contrasts) between groups (eg, between treatment groups, age groups, and performance status groups) were reviewed by 34 experts in QOL measurement and cancer treatment. The experts, blinded to actual QOL results, were asked to predict these differences. A large difference was defined as one representing unequivocal clinical relevance. A medium difference was defined as likely to be clinically relevant but to a lesser extent. A small difference was one believed to be subtle but nevertheless clinically relevant. A trivial difference was used to describe circumstances unlikely to have any clinical relevance. Actual QOL results were combined using meta-analytic techniques to estimate differences corresponding to small, medium, or large effects. Results Nine hundred eleven articles were identified, leading to 152 relevant articles (2,217 contrasts) being reviewed by at least two experts. Resulting estimates from the meta-analysis varied depending on the subscale. Thus, the recommended minimum to detect medium differences ranges from 9 (cognitive functioning) to 19 points (role functioning). Conclusion Guidelines for the size of effects are provided for the QLQ-C30 subscales. These guidelines can be used for sample size calculations for clinical trials and can also be used to aid interpretation of differences in QLQ-C30 scores.
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Scott NW, Fayers PM, Aaronson NK, Bottomley A, de Graeff A, Groenvold M, Gundy C, Koller M, Petersen MA, Sprangers MAG. Interpretation of differential item functioning analyses using external review. Expert Rev Pharmacoecon Outcomes Res 2010; 10:253-8. [PMID: 20545590 DOI: 10.1586/erp.10.22] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Differential item functioning (DIF) analyses are used to determine whether certain groups respond differently to a particular item of a test or questionnaire; however, these do not explain the reasons for observed response differences. Many studies have used external reviews of items, sometimes using blinded reviewers, to help interpret these results. The authors conducted a literature review of this topic to describe the current usage of external reviews alongside DIF analyses. It concentrated on studies of health-related quality of life instruments, but studies in other fields were also considered. Relatively few examples of blinded item reviews were identified, and these were mostly from educational studies. A case study using blinded bilingual reviewers alongside translation DIF analyses of a health-related quality of life instrument is described. Future researchers should consider conducting external item reviews alongside DIF analyses.
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Scott NW, Fayers PM, Aaronson NK, Bottomley A, de Graeff A, Groenvold M, Gundy C, Koller M, Petersen MA, Sprangers MAG. Differential item functioning (DIF) analyses of health-related quality of life instruments using logistic regression. Health Qual Life Outcomes 2010; 8:81. [PMID: 20684767 PMCID: PMC2924271 DOI: 10.1186/1477-7525-8-81] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Accepted: 08/04/2010] [Indexed: 11/10/2022] Open
Abstract
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.
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Kvam AK, Wisløff F, Fayers PM. Minimal important differences and response shift in health-related quality of life; a longitudinal study in patients with multiple myeloma. Health Qual Life Outcomes 2010; 8:79. [PMID: 20678240 PMCID: PMC2922103 DOI: 10.1186/1477-7525-8-79] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2010] [Accepted: 08/03/2010] [Indexed: 01/22/2023] Open
Abstract
Background We previously reported that changes of 6-17 percent in the EORTC QLQ-C30 scores are regarded important by patients with multiple myeloma and thus may be considered as Minimal Important Differences (MIDs). However, patients' internal standard of measurement may have changed over time (response shift, RS). In the present work, we evaluated whether myeloma patients experience RS and if this could affect the MID-estimates. Methods Between 2006 and 2008, 239 patients with multiple myeloma completed the EORTC QLQ-C30 at baseline (T1) and after three months (T2). At T2, patients were asked if they had noticed any change in the domains pain, fatigue, physical function and global quality of life. They were also asked to give a retrospective judgment of their baseline values on all the four domains. Results We found clear evidence of RS in myeloma patients. However, there were differences in both magnitude and direction between patients who stated that they improved and those who deteriorated. Deteriorating patients retrospectively reported better health-related quality of life at T1 for the domains pain, fatigue and physical function. In these patients, MIDs adjusted for RS were observed to increase up to 12 percentage points. In contrast, for patients stating that they improved, we only found evidence of statistically significant RS in the domain global quality of life. Conclusions MIDs estimated from pre-test/post-test data appeared to be robust against RS in patients reporting improvement over 3-months. This could indicate that RS has a minimal impact on the results in patients who respond to treatment, and that RS may not have an important impact on interpretation of changes reported in clinical trials where an improvement occurs. Although the effect sizes of the RSs were small, RS in deteriorating patients may have an important impact on the interpretation of changes reported in clinical trials. Trial registration The study is registered at clinicaltrials.gov, identifier NCT00290095.
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Baxter JP, Fayers PM, McKinlay AW. The clinical and psychometric validation of a questionnaire to assess the quality of life of adult patients treated with long-term parenteral nutrition. JPEN J Parenter Enteral Nutr 2009; 34:131-42. [PMID: 19920205 DOI: 10.1177/0148607109348612] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
BACKGROUND Home parenteral nutrition (HPN) is an established treatment for the management of patients with chronic intestinal failure. No quality-of-life assessment tools have been developed and validated specifically for this patient population, and previous studies have used generic instruments or techniques not validated in HPN. The assessment of quality of life (QOL) should produce clinically relevant data reflecting patients' issues. The HPN-QOL was designed to assess the QOL of HPN patients. The purpose of this study was to test the hypothesized scale structure of the questionnaire with regard to reliability and validity in a sample of patients. METHODS A provisional questionnaire was prepared following recognized guidelines and then subjected to field testing. The questionnaire was administered to 100 adult patients receiving HPN. Psychometric tests examined the reliability and validity of the questionnaire, and patients' debriefing comments were analyzed. RESULTS The provisional questionnaire was adapted using evidence from quantitative and qualitative analysis. Multitrait scaling analysis and face validity refined the questionnaire to 48 items. Compliance rates were high, and the questionnaire was well accepted. CONCLUSIONS A method of objectively assessing the QOL of patients treated with HPN has been developed. The HPN-QOL has been rigorously prepared and demonstrates psychometric and clinical validity to assess the QOL of long-term HPN patients.
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Scott NW, Fayers PM, Aaronson NK, Bottomley A, de Graeff A, Groenvold M, Gundy C, Koller M, Petersen MA, Sprangers MAG. The practical impact of differential item functioning analyses in a health-related quality of life instrument. Qual Life Res 2009; 18:1125-30. [PMID: 19653125 DOI: 10.1007/s11136-009-9521-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2009] [Accepted: 07/11/2009] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Differential item functioning (DIF) analyses are commonly used to evaluate health-related quality of life (HRQoL) instruments. There is, however, a lack of consensus as to how to assess the practical impact of statistically significant DIF results. METHODS Using our previously published ordinal logistic regression DIF results for the Fatigue scale of a HRQoL instrument as an example, the practical impact on a particular Norwegian clinical trial was investigated. The results were used to determine the difference in mean Fatigue scores assuming that the same trial was conducted in the UK. The results were then compared with published information on what would be considered a clinically important change in scores. RESULTS The item with the largest DIF effect resulted in differences between the mean English and Norwegian Fatigue scores that, although small, could be considered clinically important. Sensitivity analyses showed that larger differences were found for shorter scales, and when the proportions in each response category were equal. DISCUSSION Our scenarios suggest that translation differences in an item can result in small, but clinically important, differences at the scale score level. This is more likely to be problematic for observational studies than for clinical trials, where randomised groups are stratified by centre.
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Fielding S, Fayers PM, Ramsay CR. Investigating the missing data mechanism in quality of life outcomes: a comparison of approaches. Health Qual Life Outcomes 2009; 7:57. [PMID: 19545408 PMCID: PMC2711047 DOI: 10.1186/1477-7525-7-57] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2009] [Accepted: 06/22/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Missing data is classified as missing completely at random (MCAR), missing at random (MAR) or missing not at random (MNAR). Knowing the mechanism is useful in identifying the most appropriate analysis. The first aim was to compare different methods for identifying this missing data mechanism to determine if they gave consistent conclusions. Secondly, to investigate whether the reminder-response data can be utilised to help identify the missing data mechanism. METHODS Five clinical trial datasets that employed a reminder system at follow-up were used. Some quality of life questionnaires were initially missing, but later recovered through reminders. Four methods of determining the missing data mechanism were applied. Two response data scenarios were considered. Firstly, immediate data only; secondly, all observed responses (including reminder-response). RESULTS In three of five trials the hypothesis tests found evidence against the MCAR assumption. Logistic regression suggested MAR, but was able to use the reminder-collected data to highlight potential MNAR data in two trials. CONCLUSION The four methods were consistent in determining the missingness mechanism. One hypothesis test was preferred as it is applicable with intermittent missingness. Some inconsistencies between the two data scenarios were found. Ignoring the reminder data could potentially give a distorted view of the missingness mechanism. Utilising reminder data allowed the possibility of MNAR to be considered.
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Fayers PM, King MT. How to guarantee finding a statistically significant difference: the use and abuse of subgroup analyses. Qual Life Res 2009; 18:527-30. [PMID: 19343540 DOI: 10.1007/s11136-009-9473-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2008] [Accepted: 03/16/2009] [Indexed: 11/28/2022]
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Fayers PM, King MT. In reply to Berger "don't test for baseline imbalances unless they are known to be present?". Qual Life Res 2009; 18:401-2. [PMID: 19253032 DOI: 10.1007/s11136-009-9458-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2009] [Accepted: 02/09/2009] [Indexed: 11/26/2022]
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Scott NW, Fayers PM, Aaronson NK, Bottomley A, de Graeff A, Groenvold M, Gundy C, Koller M, Petersen MA, Sprangers MAG. Differential item functioning (DIF) in the EORTC QLQ-C30: a comparison of baseline, on-treatment and off-treatment data. Qual Life Res 2009; 18:381-8. [PMID: 19247808 DOI: 10.1007/s11136-009-9453-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2008] [Accepted: 01/31/2009] [Indexed: 10/21/2022]
Abstract
INTRODUCTION Differential item functioning (DIF) analyses can be used to explore translation, cultural, gender or other differences in the performance of quality of life (QoL) instruments. These analyses are commonly performed using "baseline" or pretreatment data. We previously reported DIF analyses to examine the pattern of item responses for translations of the European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30 QoL instrument, using only data collected prior to cancer treatment. We now compare the consistency of these results with similar analyses of on-treatment and off-treatment assessments and explore whether item relationships differ from those at baseline. METHODS Logistic regression DIF analyses were used to examine the translation of each item in each multi-item scale at the three time points, after controlling for the overall scale score and other covariates. The consistency of results at the three time points was explored. RESULTS For most EORTC QLQ-C30 subscales, the DIF results were very consistent across the three time points. Results for the Nausea and Vomiting scale varied the most across assessments. DISCUSSION The results indicated that DIF analyses were stable across each time point and that the same DIF effects were usually found regardless of the treatment status of the respondent.
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Robertson C, Langston AL, Stapley S, McColl E, Campbell MK, Fraser WD, Maclennan G, Selby PL, Ralston SH, Fayers PM. Meaning behind measurement: self-comparisons affect responses to health-related quality of life questionnaires. Qual Life Res 2009; 18:221-30. [PMID: 19142744 DOI: 10.1007/s11136-008-9435-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Accepted: 12/15/2008] [Indexed: 11/26/2022]
Abstract
PURPOSE The subjective nature of quality of life is particularly pertinent to the domain of health-related quality of life (HRQOL) research. The extent to which participants' responses are affected by subjective information and personal reference frames is unknown. This study investigated how an elderly population living with a chronic metabolic bone disorder evaluated self-reported quality of life. METHODS Participants (n = 1,331) in a multi-centre randomised controlled trial for the treatment of Paget's disease completed annual HRQOL questionnaires, including the SF-36, EQ-5D and HAQ. Supplementary questions were added to reveal implicit reference frames used when making HRQOL evaluations. Twenty-one participants (11 male, 10 female, aged 59-91 years) were interviewed retrospectively about their responses to the supplementary questions, using cognitive interviewing techniques and semi-structured topic guides. RESULTS The interviews revealed that participants used complex and interconnected reference frames to promote response shift when making quality of life evaluations. The choice of reference frame often reflected external factors unrelated to individual health. Many participants also stated that they were unclear whether to report general or disease-related HRQOL. CONCLUSIONS It is important, especially in clinical trials, to provide instructions clarifying whether 'quality of life' refers to disease-related HRQOL. Information on self-comparison reference frames is necessary for the interpretation of responses to questions about HRQOL.
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Fayers PM. Evaluating the effectiveness of using PROs in clinical practice: a role for cluster-randomised trials. Qual Life Res 2008; 17:1315-21. [PMID: 18821031 DOI: 10.1007/s11136-008-9391-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2008] [Accepted: 08/27/2008] [Indexed: 11/30/2022]
Abstract
Many of us believe there are major benefits to be gained by using patient-reported outcomes (PROs) in routine clinical practice. However, demonstrating tangible benefits has frequently proved elusive. Although randomised clinical trials (RCTs) have become accepted as the standard for comparing alternative forms of clinical interventions, when evaluating the effectiveness of PROs there are a number of challenges both in terms of study design and the subsequent analysis. Despite this, to date, of those investigators who have used RCTs, relatively few have used anything other than simple two-group randomisation and comparisons. Most of these trials have also failed to demonstrate convincing benefits to patient outcomes. We suggest that the use of PROs may result in modest yet important improvements to patient outcomes, and that these benefits may be obscured in conventional individual patient trials because of contamination effects. The advantages of alternative designs such as cross-over studies and in particular cluster-randomised trials are illustrated.
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Scott NW, Fayers PM, Aaronson NK, Bottomley A, de Graeff A, Groenvold M, Gundy C, Koller M, Petersen MA, Sprangers MAG. A simulation study provided sample size guidance for differential item functioning (DIF) studies using short scales. J Clin Epidemiol 2008; 62:288-95. [PMID: 18774693 DOI: 10.1016/j.jclinepi.2008.06.003] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2007] [Revised: 05/14/2008] [Accepted: 06/17/2008] [Indexed: 10/21/2022]
Abstract
OBJECTIVE Differential item functioning (DIF) analyses are increasingly used to evaluate health-related quality of life (HRQoL) instruments, which often include relatively short subscales. Computer simulations were used to explore how various factors including scale length affect analysis of DIF by ordinal logistic regression. STUDY DESIGN AND SETTING Simulated data, representative of HRQoL scales with four-category items, were generated. The power and type I error rates of the DIF method were then investigated when, respectively, DIF was deliberately introduced and when no DIF was added. The sample size, scale length, floor effects (FEs) and significance level were varied. RESULTS When there was no DIF, type I error rates were close to 5%. Detecting moderate uniform DIF in a two-item scale required a sample size of 300 per group for adequate (>80%) power. For longer scales, a sample size of 200 was adequate. Considerably larger sample sizes were required to detect nonuniform DIF, when there were extreme FEs or when a reduced type I error rate was required. CONCLUSION The impact of the number of items in the scale was relatively small. Ordinal logistic regression successfully detects DIF for HRQoL instruments with short scales. Sample size guidelines are provided.
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Fielding S, Fayers PM, McDonald A, McPherson G, Campbell MK. Simple imputation methods were inadequate for missing not at random (MNAR) quality of life data. Health Qual Life Outcomes 2008; 6:57. [PMID: 18680574 PMCID: PMC2531086 DOI: 10.1186/1477-7525-6-57] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2008] [Accepted: 08/04/2008] [Indexed: 11/13/2022] Open
Abstract
Objective QoL data were routinely collected in a randomised controlled trial (RCT), which employed a reminder system, retrieving about 50% of data originally missing. The objective was to use this unique feature to evaluate possible missingness mechanisms and to assess the accuracy of simple imputation methods. Methods Those patients responding after reminder were regarded as providing missing responses. A hypothesis test and a logistic regression approach were used to evaluate the missingness mechanism. Simple imputation procedures were carried out on these missing scores and the results compared to the actual observed scores. Results The hypothesis test and logistic regression approaches suggested the reminder data were missing not at random (MNAR). Reminder-response data showed that simple imputation procedures utilising information collected close to the point of imputation (last value carried forward, next value carried backward and last-and-next), were the best methods in this setting. However, although these methods were the best of the simple imputation procedures considered, they were not sufficiently accurate to be confident of obtaining unbiased results under imputation. Conclusion The use of the reminder data enabled the conclusion of possible MNAR data. Evaluating this mechanism was important in determining if imputation was useful. Simple imputation was shown to be inadequate if MNAR are likely and alternative strategies should be considered.
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Cocks K, King MT, Velikova G, Fayers PM, Brown JM. Quality, interpretation and presentation of European Organisation for Research and Treatment of Cancer quality of life questionnaire core 30 data in randomised controlled trials. Eur J Cancer 2008; 44:1793-8. [PMID: 18599286 DOI: 10.1016/j.ejca.2008.05.008] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2008] [Accepted: 05/19/2008] [Indexed: 11/26/2022]
Abstract
AIM To review reporting standard, presentation and interpretation for quality of life (QOL) outcomes in randomised controlled trials (RCTs) using the European Organisation for Research and Treatment of Cancer quality of life questionnaire core 30 (EORTC QLQ-C30). METHODS Cancer RCTs reporting EORTC QLQ-C30 data were identified and reviewed against a reporting quality checklist. Interpretation/presentation methods for QOL data were also recorded. RESULTS Eighty-two papers were reviewed. Seventy percent met criteria for high quality reporting; 94% reported mean scores; 84% presented results in tables/graphs; 80% reported p-values or statistical significance. Clinical significance was addressed in 38%. Where clinical significance was not addressed, reliance was usually on statistical significance to interpret the results. DISCUSSION EORTC QLQ-C30 results are generally reported well, although it was common to rely on statistical significance alone for interpreting results. Whilst interpretation in terms of clinical significance has improved in recent years, there is still a lack of robust clinical interpretation of QOL results even in papers reported to a high standard.
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Fayers PM. The scales were highly correlated: P = 0.0001. Qual Life Res 2008; 17:651-2. [DOI: 10.1007/s11136-008-9351-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2008] [Accepted: 04/16/2008] [Indexed: 11/28/2022]
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Baxter JP, Fayers PM, McKinlay AW. The development and translation of a treatment-specific quality of life questionnaire for adult patients on home parenteral nutrition. ACTA ACUST UNITED AC 2008. [DOI: 10.1016/j.eclnm.2007.10.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Hølen JC, Saltvedt I, Fayers PM, Hjermstad MJ, Loge JH, Kaasa S. Doloplus-2, a valid tool for behavioural pain assessment? BMC Geriatr 2007; 7:29. [PMID: 18093294 PMCID: PMC2234400 DOI: 10.1186/1471-2318-7-29] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2007] [Accepted: 12/19/2007] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The Doloplus-2 is used for behavioural pain assessment in cognitively impaired patients. Little data exists on the psychometric properties of the Doloplus-2. Our objectives were to test the criterion validity and inter-rater reliability of the Doloplus-2, and to explore a design for validations of behavioural pain assessment tools. METHODS Fifty-one nursing home patients and 22 patients admitted to a geriatric hospital ward were included. All were cognitively impaired and unable to self-report pain. Each patient was examined by an expert in pain evaluation and treatment, who rated the pain on a numerical rating scale. The ratings were based on information from the medical record, reports from nurses and patients (if possible) about pain during the past 24 hours, and a clinical examination. These ratings were used as pain criterion. The Doloplus-2 was administered by the attending nurse. Regression analyses were used to estimate the ability of the Doloplus-2 to explain the expert's ratings. The inter-rater reliability of the Doloplus-2 was evaluated in 16 patients by comparing the ratings of two nurses administrating the Doloplus-2. RESULTS There was no association between the Doloplus-2 and the expert's pain ratings (R2 = 0.02). There was an association (R2 = 0.54) between the expert's ratings and the Doloplus-2 scores in a subgroup of 16 patients assessed by a geriatric expert nurse (the most experienced Doloplus-2 administrator). The inter-rater reliability between the Doloplus-2 administrators assessed by the intra-class coefficient was 0.77. The pain expert's ratings were compared with ratings of two independent geriatricians in a sub sample of 15, and were found satisfactory (intra-class correlation 0.74). CONCLUSION It was challenging to conduct such a study in patients with cognitive impairment and the study has several limitations. The results do not support the validity of the Doloplus-2 in its present version and they indicate that it demands specific administration skills.
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Fayers PM, Langston AL, Robertson C. Implicit self-comparisons against others could bias quality of life assessments. J Clin Epidemiol 2007; 60:1034-9. [PMID: 17884598 DOI: 10.1016/j.jclinepi.2007.03.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2006] [Revised: 01/18/2007] [Accepted: 02/07/2007] [Indexed: 11/24/2022]
Abstract
OBJECTIVES To explore how patient-reported health-related quality of life (HRQL) and global health status are affected by use of differing personal reference frames. We hypothesized that implicit comparisons against self at an earlier time, against healthy peers, or against ill patients would greatly affect patients' response values. STUDY DESIGN AND SETTING Patients in a randomized trial for treatment of Paget's disease completed annual HRQL questionnaires. Supplementary questions were appended, asking the patients whether they were aware of having made implicit comparisons. RESULTS The majority of patients reported considering themselves a year ago (31% at baseline), themselves before becoming ill (23%), or other healthy people (24%), with similar proportions during follow-up. Mean HRQL scores varied substantially according to the declared frame of reference, with differences as big as 19% of the scale score, or a standardized mean effect size of 0.74 standard deviations. CONCLUSION Reported reference frames were associated with effects of similar magnitude to the differences in HRQL that are regarded as clinically important. This may be of particular concern in trials that randomize patients to management in different settings, such as treatment at home/in hospital, or surgery/chemotherapy and might bias or obscure HRQL differences.
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Fayers PM. Applying item response theory and computer adaptive testing: the challenges for health outcomes assessment. Qual Life Res 2007; 16 Suppl 1:187-94. [PMID: 17417722 DOI: 10.1007/s11136-007-9197-1] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2006] [Accepted: 02/13/2007] [Indexed: 10/23/2022]
Abstract
OBJECTIVES We review the papers presented at the NCI/DIA conference, to identify areas of controversy and uncertainty, and to highlight those aspects of item response theory (IRT) and computer adaptive testing (CAT) that require theoretical or empirical research in order to justify their application to patient reported outcomes (PROs). BACKGROUND IRT and CAT offer exciting potential for the development of a new generation of PRO instruments. However, most of the research into these techniques has been in non-healthcare settings, notably in education. Educational tests are very different from PRO instruments, and consequently problematic issues arise when adapting IRT and CAT to healthcare research. RESULTS Clinical scales differ appreciably from educational tests, and symptoms have characteristics distinctly different from examination questions. This affects the transferring of IRT technology. Particular areas of concern when applying IRT to PROs include inadequate software, difficulties in selecting models and communicating results, insufficient testing of local independence and other assumptions, and a need of guidelines for estimating sample size requirements. Similar concerns apply to differential item functioning (DIF), which is an important application of IRT. Multidimensional IRT is likely to be advantageous only for closely related PRO dimensions. CONCLUSIONS Although IRT and CAT provide appreciable potential benefits, there is a need for circumspection. Not all PRO scales are necessarily appropriate targets for this methodology. Traditional psychometric methods, and especially qualitative methods, continue to have an important role alongside IRT. Research should be funded to address the specific concerns that have been identified.
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Baxter JP, Fayers PM, McKinlay AW. A review of the instruments used to assess the quality of life of adult patients with chronic intestinal failure receiving parenteral nutrition at home. Br J Nutr 2007; 94:633-8. [PMID: 16277762 DOI: 10.1079/bjn20051533] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Home parenteral nutrition is an established method of supporting patients with intestinal failure, but this treatment may be life long and imposes severe restrictions on daily life. Impact on quality of life is an important outcome when considering the management of home parenteral nutrition patients. This paper reviews studies in which the quality of life of patients receiving home parenteral nutrition has been assessed. A systematic search of electronic databases and relevant publications was undertaken to identify generic or treatment-specific questionnaires used with home parenteral nutrition patients. Many of the thirty-four reports discovered were small studies. Nineteen used non-specific generic instruments, eight used non-validated questionnaires, four used a combination of both, and three did not use any formal tool. Few systematic patterns emerged. There are few available data on the quality of life of home parenteral nutrition patients, and there is a need for standardised, scientifically validated, treatment-specific instruments to measure quality of life in this population.
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Groenvold M, Petersen MA, Idler E, Bjorner JB, Fayers PM, Mouridsen HT. Psychological distress and fatigue predicted recurrence and survival in primary breast cancer patients. Breast Cancer Res Treat 2007; 105:209-19. [PMID: 17203386 DOI: 10.1007/s10549-006-9447-x] [Citation(s) in RCA: 214] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2006] [Accepted: 10/31/2006] [Indexed: 11/12/2022]
Abstract
This study examined whether psychological distress in newly diagnosed breast cancer patients was associated with their survival. We analyzed data from 1,588 breast cancer patients who filled in the EORTC QLQ-C30 questionnaire and the Hospital Anxiety and Depression Scale (HADS) 2 months after their primary operation. The median follow-up time was 12.9 years. Psychological distress (EORTC QLQ-C30 emotional function; HADS anxiety; HADS depression) and EORTC fatigue, physical function, and overall ratings were used to predict recurrence-free and overall survival, controlling for the known clinical and histopathological prognostic factors (biological model) using Cox multivariate regression analysis. Low levels of psychological distress (good EORTC emotional function) and low fatigue independently predicted longer recurrence-free and overall survival, controlling for biological factors. Lack of anxiety (HADS) also predicted longer recurrence-free survival. When added in combination to the biological model, fatigue remained a significant predictor of recurrence-free survival (P = 0.0004; risk ratio 1.32 (1.13-1.54)) and emotional function remained a significant predictor of overall survival (P = 0.0074; risk ratio 0.81 (0.70-0.95)). Low psychological distress and a low level of fatigue may cause a greater cancer resistance or may reflect underlying mental and physical robustness.
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MESH Headings
- Adult
- Aged
- Breast Neoplasms/mortality
- Breast Neoplasms/psychology
- Breast Neoplasms/therapy
- Carcinoma, Ductal, Breast/mortality
- Carcinoma, Ductal, Breast/psychology
- Carcinoma, Ductal, Breast/therapy
- Carcinoma, Lobular/mortality
- Carcinoma, Lobular/psychology
- Carcinoma, Lobular/therapy
- Fatigue/diagnosis
- Fatigue/etiology
- Fatigue/psychology
- Female
- Humans
- Mass Screening
- Middle Aged
- Neoplasm Recurrence, Local/diagnosis
- Neoplasm Recurrence, Local/etiology
- Neoplasm Recurrence, Local/psychology
- Personality Assessment/statistics & numerical data
- Psychometrics
- Quality of Life
- Reproducibility of Results
- Stress, Psychological/diagnosis
- Stress, Psychological/etiology
- Stress, Psychological/psychology
- Survival Rate
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Fielding S, Fayers PM, Loge JH, Jordhøy MS, Kaasa S. Methods for handling missing data in palliative care research. Palliat Med 2006; 20:791-8. [PMID: 17148533 DOI: 10.1177/0269216306072555] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Missing data is a common problem in palliative care research due to the special characteristics (deteriorating condition, fatigue and cachexia) of the population. Using data from a palliative study, we illustrate the problems that missing data can cause and show some approaches for dealing with it. Reasons for missing data and ways to deal with missing data (including complete case analysis, imputation and modelling procedures) are explored. Possible mechanisms behind the missing data are: missing completely at random, missing at random or missing not at random. In the example study, data are shown to be missing at random. Imputation of missing data is commonly used (including last value carried forward, regression procedures and simple mean). Imputation affects subsequent summary statistics and analyses, and can have a substantial impact on estimated group means and standard deviations. The choice of imputation method should be carried out with caution and the effects reported.
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Hølen JC, Hjermstad MJ, Loge JH, Fayers PM, Caraceni A, De Conno F, Forbes K, Fürst CJ, Radbruch L, Kaasa S. Pain assessment tools: is the content appropriate for use in palliative care? J Pain Symptom Manage 2006; 32:567-80. [PMID: 17157759 DOI: 10.1016/j.jpainsymman.2006.05.025] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2006] [Revised: 05/30/2006] [Accepted: 05/31/2006] [Indexed: 11/12/2022]
Abstract
Inadequate pain assessment prevents optimal treatment in palliative care. The content of pain assessment tools might limit their usefulness for proper pain assessment, but data on the content validity of the tools are scarce. The objective of this study was to examine the content of the existing pain assessment tools, and to evaluate the appropriateness of different dimensions and items for pain assessment in palliative care. A systematic search was performed to find pain assessment tools for patients with advanced cancer who were receiving palliative care. An ad hoc search with broader search criteria supplemented the systematic search. The items of the identified tools were allocated to appropriate dimensions. This was reviewed by an international panel of experts, who also evaluated the relevance of the different dimensions for pain assessment in palliative care. The systematic literature search generated 16 assessment tools while the ad hoc search generated 64. Ten pain dimensions containing 1,011 pain items were identified by the experts. The experts ranked intensity, temporal pattern, treatment and exacerbating/relieving factors, location, and interference with health-related quality of life as the most important dimensions. None of the assessment tools covered these dimensions satisfactorily. Most items were related to interference (231) and intensity (138). Temporal pattern (which includes breakthrough pain), ranked as the second most important dimension, was covered by 29 items only. Many tools include dimensions and items of limited relevance for patients with advanced cancer. This might reduce compliance and threaten the validity of the assessment. New tools should reflect the clinical relevance of different dimensions and be user-friendly.
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