Mapping the Cancer-Specific EORTC QLQ-C30 to the Preference-Based EQ-5D, SF-6D, and 15D Instruments

Objectives:  To estimate models, via ordinary least squares regression, for predicting Euro Qol 5D (EQ-5D), Short Form 6D (SF-6D), and 15D utilities from scale scores of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30).
Methods:  Forty-eight gastric cancer patients, split up into equal subgroups by age, sex, and chemotherapy scheme, were interviewed, and the survey included the QLQ-C30, SF-36, EQ-5D, and 15D instruments, along with sociodemographic and clinical data. Model predictive ability and explanatory power were assessed by root mean square error (RMSE) and adjusted R ² values, respectively. Pearson's r between predicted and reported utility indices was compared. Three random subsamples, half in size the initial sample, were created and used for "external" validation of the modeling equations.
Results:  Explanatory power was high, with adjusted R ² reaching 0.909, 0.833, and 0.611 for 15D, SF-6D, and EQ-5D, respectively. After normalization of RMSE to the range of possible values, the prediction errors were 12.0, 5.4, and 5.6% for EQ-5D, SF-6D, and 15D, respectively. The estimation equations produced a range of utility scores similar to those achievable by the standard scoring algorithms. Predicted and reported indices from the validation samples were comparable thus confirming the previous results.
Conclusions:  Evidence on the ability of QLQ-C30 scale scores to validly predict 15D and SF-6D utilities, and to a lesser extent, EQ-5D, has been provided. The modeling equations must be tried in future studies with larger and more diverse samples to confirm their appropriateness for estimating quality-adjusted life-year in cancer-patient trials including only the QLQ-C30.     

Interchangeability of the EQ-5D and the SF-6D in Long-Lasting Low Back Pain

Objectives:  The objective of this study was to investigate the interchangeability of the EuroQol 5D (EQ-5D) and the Short Form 6D (SF-6D) in individuals with long-lasting low back pain to guide the optimal choice of instrument and to inform decision-makers about any between-measure discrepancy, which require careful interpretation of the results of cost-utility evaluations.
Methods:  A cross-sectional study was conducted across 275 individuals who had spinal surgery on indication of chronic low back pain. EQ-5D and SF-6D were mailed to respondents for self-completion. Statistical analysis of between-measure agreement (using English weights) was based on Bland and Altman's limits of agreement and a series of linear regressions.
Results:  A moderate mean difference of 0.085 (SD 0.241) was found, but because it masked more severe bidirectional variation, the expected variation between observations of EQ-5D and SF-6D in future studies was estimated at 0.546. The EQ-5D's N3 term alone explained a factor of 0.79 of the variation in between-measure differences, while the explanatory value of adding variables of age, sex, diagnosis, previous surgery, and occupational status was basically zero. A final model including only dummy variables for the N3 term and five identified framing effects explained a factor of 0.86 of the variation in between-measure differences.
Conclusions:  Although the EQ-5D and the SF-6D are both psychometrically valid for generic outcome assessment in long-lasting low back pain, it appears that they cannot generally be used interchangeably for measurement of preference values. Sensitivity analysis examining the impact of between-measure discrepancy thus remains a necessary condition for the interpretation of the results of cost-utility evaluations.     

Mapping the EORTC QLQ C-30 onto the EQ-5D Instrument: The Potential to Estimate QALYs without Generic Preference Data

Objectives:  The aim of this article is to map the European Organization for Research and Treatment of Cancer (EORTC) QLQ C-30 onto the EQ-5D measure to enable the estimation of health state values based on the EORTC QLQ C-30 data. The EORTC QLQ C-30 is of interest because it is the most commonly used instrument to measure the quality of life of cancer patients.
Methods:  Regression analysis is used to establish the relationship between the two instruments. The performance of the model is assessed in terms of how well the responses to the EORTC QLQ C-30 predict the EQ-5D responses for a separate data set.
Results:  The results showed that the model explaining EQ-5D values predicted well. All of the actual values were within the 95% confidence intervals of the predicted values. More importantly, predicted difference in quality-adjusted life-years (QALYs) between the arms of the trial was almost identical to the actual difference.
Conclusion:  There is potential to estimate EQ-5D values using responses to the disease-specific EORTC QLQ C-30 measure of quality of life. Such potential implies that in studies that do not include disease-specific measures, it might still be possible to estimate QALYs.     

Mapping the English and Chinese Versions of the Functional Assessment of Cancer Therapy–General to the EQ-5D Utility Index

Objective:  This study aims to develop a function for mapping the English and Chinese versions of the Functional Assessment of Cancer Therapy–General (FACT–G) scores to the EuroQoL Group's EQ-5D utility index and to test whether a single function is sufficient for the two language versions.
Methods:  A baseline survey of 558 cancer patients in Singapore using the FACT–G and EQ-5D was conducted (308 English and 250 Chinese questionnaires). Regression models were used to predict the EQ-5D utility index values based on the FACT–G scores and thus derive a mapping equation. Data from a follow-up survey of the patients were used to validate the results.
Results:  The FACT–G Social/Family scale was not associated with the EQ-5D utility index ( P  = 0.701). There was no interaction between language version and the predictors (each P  > 0.1). An equation that maps the FACT–G Physical, Emotional, and Functional well-being scales to the EQ-5D utility index was derived. In the validation sample, the mean observed utility values was larger than the mapped by only 0.005 (95% confidence interval [CI]−0.006 to 0.016), but the mean absolute difference was 0.083 (95% CI 0.076 to 0.090).
Conclusions:  At the group level, but not individual level, the equation developed can accurately map the English and Chinese versions of the FACT–G scores to the EQ-5D utility index.     

Validity, Responsiveness, and Minimal Important Difference for the SF-6D Health Utility Scale in a Spinal Cord Injured Population

Objective:  To determine the feasibility, acceptability, discriminative validity, responsiveness, and minimal important difference (MID) of the SF-6D for people with spinal cord injury (SCI).
Methods:  A total of 305 people with SCI completed the SF-36 health status questionnaire at baseline and at subsequent occurrence of a urinary tract infection (UTI) or 6-month follow-up. Normative SF-36 data were obtained from the Australian Bureau of Statistics. SF-36 scores were transformed to SF-6D utility values using Brazier's algorithm. We used UTI as the external criterion of clinically important change to determine responsiveness and two categories of the SF-36 transition question ("somewhat worse" and "somewhat better") as the external criterion to determine the MID. Derived SF-12 responsiveness was also assessed.
Results:  The mean SF-6D values were: 0.68 (SD 0.21, n = 305) all patients; 0.66 (SD 0.19, n = 167) tetraplegia; 0.72 (SD 0.26, n = 138) paraplegia; 0.57 (SD 0.15, n = 138) with UTI. The Australian normative SF-6D mean value was 0.80 (SD 0.14, n = 18,005). The SF-6D was able to discriminate between SCI and the Australian normative sample (effect size [ES] = 0.86), tetraplegia–paraplegia (ES = 0.23), and it was responsive to UTI (ES = 0.86 SF-36 variant, ES = 0.92 SF-12 variant). The MID for respondents who reported being somewhat worse or somewhat better at follow-up was 0.03 (SD 0.17, n = 108/305), while the MID for only those who were somewhat worse was 0.10 (SD 0.14, n = 58).
Conclusions:  The content of the SF-6D is more appropriate than that of the SF-36 for this physically impaired population. The SF-6D has discriminative power and is responsive to clinically important change because of UTI. The MID is consistent with published estimates for other disease groups.     

Utility scores for different health states related to depression: individual participant data analysis

Objectives

Depression is associated with considerable impairments in health-related quality-of-life. However, the relationship between different health states related to depression severity and utility scores is unclear. The aim of this study was to evaluate whether utility scores are different for various health states related to depression severity.

Methods

We gathered individual participant data from ten randomized controlled trials evaluating depression treatments. The UK EQ-5D and SF-6D tariffs were used to generate utility scores. We defined five health states that were proposed from American Psychiatric Association and National Institute for Clinical Excellence guidelines: remission, minor depression, mild depression, moderate depression, and severe depression. We performed multilevel linear regression analysis.

Results

We included 1629 participants in the analyses. The average EQ-5D utility scores for the five health states were 0.70 (95% CI 0.67–0.73) for remission, 0.62 (95% CI 0.58–0.65) for minor depression, 0.57 (95% CI 0.54–0.61) for mild depression, 0.52 (95%CI 0.49–0.56) for moderate depression, and 0.39 (95% CI 0.35–0.43) for severe depression. In comparison with the EQ-5D, the utility scores based on the SF-6D were similar for remission (EQ-5D?=?0.70 vs. SF-6D?=?0.69), but higher for severe depression (EQ-5D?=?0.39 vs. SF-6D?=?0.55).

Conclusions

We observed statistically significant differences in utility scores between depression health states. Individuals with less severe depressive symptoms had on average statistically significant higher utility scores than individuals suffering from more severe depressive symptomatology. In the present study, EQ-5D had a larger range of values as compared to SF-6D.

     

Preference-Based Quality of Life of Patients on Renal Replacement Therapy: A Systematic Review and Meta-Analysis

Objectives:  Various utility measures have been used to assess preference-based quality of life of patients with end-stage renal disease (ESRD). The purposes of this study were to summarize the literature on utilities of hemodialysis (HD), peritoneal dialysis (PD), and renal transplantation (RTx) patients, to compare utilities between these patient groups, and to obtain estimates for quality-of-life adjustment in economic analyses.
Methods:  We searched the English literature for studies that reported visual analog scale (VAS), time trade-off (TTO), standard gamble (SG), EuroQol-5D (EQ-5D), and health utilities index (HUI) values of ESRD patients. We extracted patient characteristics and utilities and calculated mean utilities and 95% confidence intervals (CIs) for categories defined by utility measure and treatment modality using random-effects models.
Results:  We identified 27 articles that met the inclusion criteria. VAS articles were too heterogeneous to summarize quantitatively and we found only one study reporting HUI values. Thus, we summarized utilities from TTO, SG, and EQ-5D studies. Mean TTO and EQ-5D-index values were lower for dialysis compared to RTx patients, though not statistically significant for TTO values (TTO values: HD 0.61, 95% CI 0.54–0.68; PD 0.73, 95% CI 0.61–0.85; RTx 0.78, 95% CI 0.63–0.93; EQ-5D-index values: HD 0.56, 95% CI 0.49–0.62; PD 0.58, 95% CI 0.50–0.67; RTx 0.81, 95% CI 0.72–0.90). Mean HD versus PD associated TTO, EQ-5D-index and EQ-VAS values were not statistically significantly different.
Conclusion:  RTx patients tended to have a higher utility than dialysis patients. Among HD and PD patients, there were no statistically significant differences in utility.     

The Impact of Health Literacy on Health-Related Quality of Life (HRQoL) and Utility Assessment among Patients with Rheumatic Diseases

Objectives:  The objective of this study was to investigate the impact of health literacy (HL) on health-related quality of life (HRQoL) and utility assessment among patients with rheumatic diseases.
Methods:  HL was measured by the rapid estimate of adult literacy in medicine (REALM) and was characterized as low or adequate. HRQoL and utility scores were assessed using the SF-36, SF-6D, and EQ-5D. Comparisons of sociodemographics and HRQoL in patients with low or adequate HL were made using t test, chi-square, or Mann–Whitney U tests. Spearman's correlation and partial correlations were used to study the relationship between HL, HRQoL, and utility scores, with significant correlations further explored using multiple linear regression models.
Results:  Data were analyzed from 199 subjects. Patients with adequate HL had significantly higher education levels, better dwelling status, lower disease activity, and better physical functioning (PF). There was a significant although weak correlation between HL level and PF. After adjustment, HL level was shown to independently explain 3.7% of the variance in the PF score. Nevertheless, there was no impact of HL on utility assessment or other HRQoL domains.
Conclusion:  HL did not impact HRQoL in general, but was found to have a weak impact on the PF of patients with rheumatic diseases.     

Normative Estimates and Agreement Between 2 Measures of Health-Related Quality of Life in Older People With Frailty: Findings From the Community Ageing Research 75+ Cohort

BackgroundPrevious studies have summarized evidence on health-related quality of life for older people, identifying a range of measures that have been validated, but have not sought to present results by degree of frailty. Furthermore, previous studies did not typically use quality-of-life measures that generate an overall health utility score. Health utility scores are a necessary component of quality-adjusted life-year calculations used to estimate the cost-effectiveness of interventions.MethodsWe calculated normative estimates in mean and standard deviation for EQ-5D-5L, short-form 36-item health questionnaire in frailty (SF-36), and short-form 6-dimension (SF-6D) for a range of established frailty models. We compared response distributions across dimensions of the measures and investigated agreement using Bland-Altman and interclass correlation techniques.ResultsThe EQ-5D-5L, SF-36, and SF-6D scores decrease and their variability increases with advancing frailty. There is strong agreement between the EQ-5D-5L and SF-6D across the spectrum of frailty. Agreement is lower for people who are most frail, indicating that different components of the 2 instruments may have greater relevance for people with advancing frailty in later life. There is a greater risk of ceiling effects using the EQ-5D-5L rather than the SF-6D.ConclusionsWe recommend the SF-36/SF-6D as an appropriate measure of health-related quality of life for clinical trials if fit older people are the planned target. In trials of interventions involving older people with increasing frailty, we recommend that both the EQ-5D-5L and SF36/SF6D are included, and are used in sensitivity analyses as part of cost-effectiveness evaluation.     

Mapping from Disease-Specific Measures to Utility: An Analysis of the Relationships between the Inflammatory Bowel Disease Questionnaire and Crohn''s Disease Activity Index in Crohn''s Disease and Measures of Utility

OBJECTIVES: To examine the relationship between the Inflammatory Bowel Disease Questionnaire (IBDQ), Crohn's Disease Activity Index (CDAI) and measures of utility (EQ-5D and the SF-6D indexes), and to estimate algorithms to map the two utility values from IBDQ and CDAI scores. METHODS: A large data set from clinical trials in Crohn's disease provided contemporaneous patient responses to all four questionnaires. Paired observations from multiple time-points were analyzed. We calculated mean utility scores by IBDQ and CDAI score deciles; Spearman correlation coefficients for paired observations between IBDQ and EQ-5D (n = 3320) and IBDQ and SF-6D (n = 3230), and explored regression models using maximum likelihood estimation. The IBDQ/SF-6D model was validated against paired observations from an independent data set. RESULTS: The IBDQ decile analysis demonstrated a consistent positive relationship with both utility indexes. Correlations between the IBDQ and both the EQ-5D and SF-6D were statistically significant (P < 0.0001), with correlation coefficients of 0.76 and 0.85, respectively. A simple linear model between EQ-5D and IBDQ explained 45% of the variance. The residuals plot for the IBDQ/SF-6D model suggested some nonlinearity and a nonlinear model explained 69% of the variance. In the validation analysis, no statistically significant difference was observed between the mean observed SF-6D and the SF-6D scores estimated using the IBDQ/SF-6D regression model. CONCLUSIONS: Given the strength, consistency, and predictable characteristics of the relationships, the algorithms appear to provide valuable and valid methods to estimate utilities from IBDQ scores (but not CDAI) in trials of Crohn's disease patients that have collected IBDQ scores but not utilities.     

An investigation into the empirical validity of the EQ-5D and SF-6D based on hypothetical preferences in a general population

BACKGROUND: An important consideration for studies that derive utility scores using multi-attribute utility measures is the psychometric integrity of the measurement instrument. Of particular importance is the requirement to establish the empirical validity of multi-attribute utility measures; that is, whether they generate utility scores that, in practice, reflect people's preferences. We compared the empirical validity of EQ-5D versus SF-6D utility scores based on hypothetical preferences in a large, representative sample of the English population. METHODS: Adult participants in the 1996 Health Survey for England (n=16 443) formed the basis of the investigation. The subjects were asked to complete the EQ-5D and SF-36 measures. Their responses were converted into utility scores using the York A1 tariff set and the SF-6D utility algorithm, respectively. One-way analysis of variance was used to test the hypothetically constructed preference rule that each set of utility scores differs significantly by self-reported health status (categorised as very good, good, fair, bad or very bad). The degree to which EQ-5D and SF-6D utility scores reflect alternative configurations of self-reported health status; illness, disability or infirmity, and medication use was tested using the relative efficiency statistic and receiver operating characteristic (ROC) curves. RESULTS: The mean utility score for the EQ-5D was 0.845 (95% CI: 0.842, 0.849), whilst the mean utility score for the SF-6D was 0.799 (95% CI: 0.797, 0.802), representing a mean difference in utility score of 0.046 (95% CI: 0.044, 0.049; p<0.001). Bland-Altman plots displayed considerable lack of agreement between the two measures, particularly at the lower end of the utility scale. Both measures demonstrated statistically significant differences between subjects who described their health status as very good, good, fair, bad or very bad (p<0.001), as well as monotonically decreasing utility scores (test for linear trend: p<0.001). The SF-6D was between 30.9 and 100.4% more efficient than the EQ-5D at detecting differences in self-reported health status, and between 10.4 and 45.6% more efficient at detecting differences in illness, disability or infirmity and medication use. The area under the curve scores generated by the ROC curves were significantly higher for the SF-6D at the 0.1% significance level when self-reported health status was dichotomised as very good versus good, fair, bad or very bad. However, the AUC scores did not reveal any significant differences in the discriminatory powers of the measures when alternative configurations of illness, disability or infirmity and medication use were examined. CONCLUSIONS: This study provides evidence that the SF-6D is an empirically valid and efficient alternative multi-attribute utility measure to the EQ-5D, and is capable of discriminating between external indicators of health status. However, health economists should also consider other psychometric properties, such as practicality and reliability, when selecting either measure for evaluative purposes.     

Health-Related Quality of Life (HRQL) and Continuous Antipsychotic Treatment: 3-year Results from the Schizophrenia Health Outcomes (SOHO) Study

Objectives:  We investigated the association between continuous antipsychotic use and health-related quality of life (HRQL) 3-year change in the European Schizophrenia Outpatients Health Outcomes (EU-SOHO) study.
Methods:  EU-SOHO is an observational study of outcomes associated with antipsychotic treatment for schizophrenia in an outpatient setting. HRQL was assessed at study entry and at 6, 12, 18, 24, 30, and 36 months using the EuroQol-5D (EQ-5D). UK population time trade-off (TTO) tariffs were applied to the self-rated EQ-5D health states to calculate HRQL ratings (0 = death, 1 = best). An epoch analysis approach was used as a conceptual framework to analyze the longitudinal data. Follow-up was divided into epochs or periods of continuous treatment. When a patient changed antipsychotic treatment, he or she was considered to have a new observation. Multilevel models were employed to evaluate the association of HRQL with medication and other clinical and sociodemographic variables for each epoch. A total of 9340 patients were analyzed (42.1% women; mean age 40 years).
Results:  Mean EQ-5D scores increased over time; the largest improvement occurred in the first 6 months (mean increase of 0.19). Longer duration of illness and older age at first treatment were associated with worse baseline EQ-5D scores. Improvements in EQ-5D scores were greater for more socially active patients or those in paid employment. Few significant differences were found between antipsychotic medications. Olanzapine and clozapine were associated with higher HRQL increases.
Conclusions:  Continuous antipsychotic treatment is associated with important HRQL benefits at 3 years, most of which occurs during the first 6 months. Although some medications are associated with better HRQL outcomes, differences are small.     

EQ-5D Versus SF-12 in Coronary Patients: Are They Interchangeable?

ObjectivesThe aim of this study was to compare EuroQol five-dimensional (EQ-5D) utility scores and six-dimensional health state classification (SF-6D) utility scores (derived from the 12-Item Short-Form Health Survey [SF-12]) by using a large European sample of patients with stable coronary heart disease. Special attention was given to country-specific results.MethodsData from the EURopean Action on Secondary and Primary Prevention by Intervention to Reduce Events III (EUROASPIRE III) survey were used. Patients hospitalized for a coronary artery bypass graft, percutaneous coronary intervention, acute myocardial infarction, or myocardial ischemia were interviewed and examined at least 6 months after their acute event. Health-related quality of life was assessed by using the EQ-5D and the SF-12. SF-12 outcomes were converted to SF-6D utility values, allowing comparison between both measures.ResultsBoth EQ-5D and SF-6D results were available for 7472 patients with coronary heart disease from 20 European countries. The measures were significantly correlated (intraclass correlation coefficient = 0.536); however, large differences between the two measures remain. A total of 28.8% of the patients reported a ceiling effect on the EQ-5D instrument, whereas only 4.2% of the patients reported full health based on the SF-6D. Especially the mental component does not seem to be completely captured by the EQ-5D instrument. Furthermore, patients with worse EQ-5D outcomes were more likely to have better SF-6D results, whereas patients with better EQ-5D outcomes were more likely to have worse SF-6D results.ConclusionsBoth measures are not interchangeable. Whereas the main disadvantage of the EQ-5D questionnaire is its ceiling effect, the potential advantages of SF-12 might disappear when converting the outcomes into an SF-6D utility, because of the small differences between patients.     

Estimating health utilities in patients with asthma and COPD: evidence on the performance of EQ-5D and SF-6D

Objective  The objective of this study was to understand systematic differences in utility values derived from the EQ-5D and the SF-6D in two respiratory populations with heterogeneous disease severity. Methods  This study involved secondary analysis of data from two cross-sectional surveys of patients with asthma (N = 228; Hungary) and COPD (N = 176; Sweden). Disease severity was defined according to GINA and GOLD guidelines for asthma and COPD, respectively. EQ-5D and SF-6D scores and their distributional characteristics were compared across the two samples by disease severity level. Results  Within each patient population, mean EQ-5D and SF-6D scores were similar for the overall group and for those with moderate disease. Mean scores varied for patients with mild and severe disease. EQ-5D versus SF-6D scores in the asthma group by severity levels were 0.89 versus 0.80, 0.70 versus 0.73, 0.63 versus 0.64, and 0.51 versus 0.63, respectively. EQ-5D versus SF-6D scores in the COPD group by severity levels were 0.85 versus 0.80, 0.73 versus 0.73, 0.74 versus 0.73, and 0.53 versus 0.62, respectively. Conclusions  Results suggest the EQ-5D and SF-6D do not yield consistent utility values in patients with asthma and COPD due to differences in underlying valuation techniques and the EQ-5D’s limited response options relative to mild disease.     

A comparison of generic, indirect utility measures (the HUI2, HUI3, SF-6D, and the EQ-5D) and disease-specific instruments (the RAQoL and the HAQ) in rheumatoid arthritis

Rheumatoid arthritis (RA) is a common, chronic disease where health-related quality of life (HRQL) is one of the main goals of therapy. As such, instruments used to measure HRQL in RA must be able to discriminate across RA severity. The two basic categories of instruments used to measure HRQL are generic instruments and disease-specific instruments. Generic instruments can be further subdivided into preference-based measures which yield both single and multi-attribute utility values anchored at zero (death) and 1.00 (perfect health) as a measure of HRQL. The scores from these types of instruments can be integrated into cost-utility analyses as the weightings for quality adjusted life years. We assessed the construct validity of utility scores from four generic preference-based measures (the Health Utilities Index 2 and 3 (HUI2, HUI3), the EuroQol 5D (EQ-5D), and the Short Form 6-D (SF-6D) and disease specific measures (the Rheumatoid Arthritis Quality of Life Questionnaire (RAQoL) and the Health Assessment Questionnaire (HAQ)) in a sample of 313 RA patients in British Columbia, Canada. We also estimated the minimally important differences (MID) for each of the measures. Generally, as anticipated, the disease-specific measures were better able to discriminate across groups with higher RA severity; however, utility scores from each of the scales also appeared to discriminate well across RA severity categories. The MID values agreed with those previously reported in the literature for the HUI2, SF-6D and the HAQ and provided new information for the HUI3, EQ-5D and the RAQoL. We conclude that the all of the preference-based utility measures that were evaluated appear to adequately discriminate across levels of RA severity.     

Assessment of health-related quality of life in individuals with depressive symptoms: validity and responsiveness of the EQ-5D-3L and the SF-6D

Background

The EQ-5D and the SF-6D are examples of commonly used generic preference-based instruments for assessing health-related quality of life (HRQoL). However, their suitability for mental disorders has been repeatedly questioned.

Objective

To assess the responsiveness and convergent validity of the EQ-5D-3L and SF-6D in patients with depressive symptoms.

Methods

The data analyzed were from cardiac patients with depressive symptoms and were collected as part of the SPIRR-CAD (Stepwise Psychotherapy Intervention for Reducing Risk in Coronary Artery Disease) trial. The EQ-5D-3L and SF-6D were compared with the HADS (Hospital Anxiety and Depression Scale) and PHQ-9 (Patient Health Questionnaire) as disease-specific instruments. Convergent validity was assessed using Spearman’s rank correlation. Effect sizes were calculated and ROC analysis was performed to determine responsiveness.

Results

Data from 566 patients were analysed. The SF-6D correlated considerably better with the disease-specific instruments (|r_s|= 0.63–0.68) than the EQ-5D-3L (|r_s|= 0.51–0.56). The internal responsiveness of the SF-6D was in the upper range of a small effect (ES: − 0.44 and − 0.47), while no effect could be determined for the EQ-5D-3L. Neither the SF-6D nor the EQ-5D-3L showed acceptable external responsiveness for classifying patients’ depressive symptoms as improved or not improved. The ability to detect patients whose condition has deteriorated was only acceptable for the EQ-5D-3L.

Conclusion

Overall, both the convergent validity and responsiveness of the SF-6D are better than those of the EQ-5D-3L in patients with depressive symptoms. The SF-6D appears, therefore, more recommendable for use in studies to evaluate interventions for this population.

     

Predicting the Short Form-6D Preference-Based Index Using the Eight Mean Short Form-36 Health Dimension Scores: Estimating Preference-Based Health-Related Utilities When Patient Level Data Are not Available

Objective:  The objective is to derive an algorithm to predict a cohort preference-based short form-6D (short form-6D) score using the eight mean health dimension scores from the short form-36 (SF-36) when patient level data are not available.
Methods:  Health-related quality of life data (N = 6890) covering a wide range of health conditions was used to explore the relationship between the SF-6D and the eight health dimension scores. Models obtained using ordinary least square regressions were compared for goodness of fit and predictive abilities on both within-sample subgroups and out-of-sample published data sets.
Results:  The models explained more than 83% of the variance in the individual SF-6D scores with a mean absolute error of 0.040. When using mean health dimension scores from within-sample subgroups and out-of-sample published data sets, the majority of predicted scores were well within the minimal important difference (0.041) for the SF-6D.
Conclusions:  This article presents a mechanism to estimate a mean cohort preference-based SF-6D score using the eight mean health dimension scores of the SF-36. Using published summary statistics, the out-of-sample validation demonstrates that the algorithms can be used to inform both clinical and economic research. Further research is required in different health conditions.     

Comparison of the minimally important difference for two health state utility measures: EQ-5D and SF-6D

Background: The SF-6D and EQ-5D are both preference-based measures of health. Empirical work is required to determine what the smallest change is in utility scores that can be regarded as important and whether this change in utility value is constant across measures and conditions. Objectives: To use distribution and anchor-based methods to determine and compare the minimally important difference (MID) for the SF-6D and EQ-5D for various datasets. Methods: The SF-6D is scored on a 0.29–1.00 scale and the EQ-5D on a −0.59–1.00 scale, with a score of 1.00 on both, indicating ‘full health’. Patients were followed for a period of time, then asked, using question 2 of the SF-36 as our anchor, if their general health is much better (5), somewhat better (4), stayed the same (3), somewhat worse (2) or much worse (1) compared to the last time they were assessed. We considered patients whose global rating score was 4 or 2 as having experienced some change equivalent to the MID. This paper describes and compares the MID and standardised response mean (SRM) for the SF-6D and EQ-5D from eight longitudinal studies in 11 patient groups that used both instruments. Results: From the 11 reviewed studies, the MID for the SF-6D ranged from 0.011 to 0.097, mean 0.041. The corresponding SRMs ranged from 0.12 to 0.87, mean 0.39 and were mainly in the ‘small to moderate’ range using Cohen’s criteria, supporting the MID results. The mean MID for the EQ-5D was 0.074 (range −0.011–0.140) and the SRMs ranged from −0.05 to 0.43, mean 0.24. The mean MID for the EQ-5D was almost double that of the mean MID for the SF-6D. Conclusions: There is evidence that the MID for these two utility measures are not equal and differ in absolute values. The EQ-5D scale has approximately twice the range of the SF-6D scale. Therefore, the estimates of the MID for each scale appear to be proportionally equivalent in the context of the range of utility scores for each scale. Further empirical work is required to see whether or not this holds true for other utility measures, patient groups and populations.     

Comparing SF-6D and EQ-5D utilities across groups differing in health status

Objectives  To compare the EQ-5D and SF-6D within socio-demographic and clinical groups in a representative sample (n = 1,005) of the Greek general population and to examine mean utility differences across groups differing in health in this population and in a highly morbid disease sample (diabetes, n = 215). Methods  Association and level of agreement between instruments were estimated with Pearson’s r and the intraclass correlation coefficient (ICC), respectively. Paired-samples t-test was used to identify significant score differences, which were regarded as minimally important differences (MID) when they exceeded 0.03. The EQ-VAS was used to classify individuals into health status groups, covering the range from very poor to very good health, and the same classification was used in the diabetes sample. Results  EQ-5D and SF-6D were in agreement and strongly correlated over the entire sample (ICC = 0.536, P < 0.001 and r = 0.662, P < 0.001), but correlation varied according to socio-demographic factors and clinical conditions. In healthier responders, EQ-5D scores were significantly higher than SF-6D scores (P < 0.001) and differences constituted MIDs. Contrarily, in individuals with clinical conditions, SF-6D scores were predominantly higher than EQ-5D. The pattern of results was replicated in the disease sample as well. Conclusions  The hypotheses that EQ-5D generates higher scores in healthier populations and the SF-6D in less healthier groups were confirmed. Based on the evidence provided here, EQ-5D and SF-6D measuring discrepancies generate utility differences across VAS-based health groups, which warrant further within-sample investigation.     

A Catalogue of EQ-5D Utility Weights for Chronic Diseases among Noninstitutionalized Community Residents in Korea

Objective:  The main purpose of this study is to provide a national catalog of preference-based utility weights associated with major chronic diseases in Korea.
Methods:  The 2005 Korea National Health and Nutrition Examination Survey was used to get EQ-5D scores for 27 major chronic diseases. The independent detrimental effect of each chronic disease was estimated using a censored least absolute deviations regression.
Results:  The respondents (60.5%) rated their health as perfect or 11111 on the EQ-5D scale showing ceiling effect. Stroke (0.5067∼0.5756) was the condition of the lowest EQ-5D utility weight and was followed by renal failure (0.6637∼0.7739), angina pectoris (0.7325∼0.8364), and arthritis (0.7621∼0.8644). The marginal impact of each chronic disease after adjusting for age, sex, education, income, marital status, and the number of comorbid conditions was largest in stroke, arthritis, cancer, renal failure, and herniated disc.
Conclusion:  This study provided a nationally representative catalog of utility weights for major chronic diseases in Korea. The three most burdensome chronic diseases among Korean adults based on the regression analysis were stroke, arthritis, and cancer.