Responsiveness of generic health-related quality of life measures in stroke

Objective: To compare five preference-based generic measures of health-related quality of life (HRQOL) in terms of change scores, correlations among change scores, responsiveness, and quality adjusted life-years (QALYs) gained. Design: Observational longitudinal cohort study where clinical measures and self-assessed HRQOL measures were administered to stroke patients at baseline and at 6 months. Patients were categorized as ‘stable’, ‘some improvement’ and ‘large improvement’ using the Barthel Index, Modified Rankin Scale (MRS), and Center for Epidemiologic Studies Depression Scale (CES-D). For each group, paired t -tests and variants of effect size were used to compare the responsiveness of preference-based HRQOL summary scores, including the EQ-5D VAS and index-based score, SF-6D, and Health Utilities Index (HUI) Mark 2 (HUI2) and Mark 3 (HUI3) overall utility scores. Results: Ninety-eight of 124 (79%) patients completed the 6-month follow-up. Change scores of the EQ-Index, HUI2, and HUI3 were strongly correlated with changes in the Barthel Index and MRS, while the EQ-5D VAS had higher correlation with CES-D change scores than the other measures. The SF-6D, HUI3, and EQ-Index were generally more responsive than the HUI2 and EQ-5D Visual analogue scale (EQ-VAS). QALY estimates based on the EQ-5D index and HUI3 were twice as large as estimates based on the SF-6D and HUI2. Conclusions : The results of this study may assist in informing the selection of a preference-based generic HRQOL measure, although choice will also depend on study goals and context. We would caution against the generalization of the study results on responsiveness to conditions when more subtle change is expected.     

Comparison of the Health Utilities Index Mark 3 (HUI3) and the EuroQol EQ-5D in patients treated for intermittent claudication

The Health Utilities Index Mark 3 (HUI3) and the EuroQol EQ-5D (EQ-5D) were compared to each other and to other quality-of-life (QoL) measures in patients treated for intermittent claudication. A total of 88 patients with intermittent claudication completed the HUI3, EQ-5D, RAND 36-Item Health Survey 1.0, time tradeoff, standard gamble, and rating scale before revascularization and at follow-up at 1 month, 3 months, and 1 year. The effect of treatment on the HUI3 and EQ-5D dimensions and the overall scores, calculated using published formulas based on societal preferences, were compared. After 1 month of treatment, the majority of patients showed improvement on the HUI3 dimensions ambulation and pain and on the EQ-5D dimensions mobility, usual activities, and pain/discomfort. The mean HUI3 score was significantly higher than the mean EQ-5D score (0.66 and 0.57, respectively, p < 0.01) before treatment. After treatment, however, they were not significantly different from each other (e.g., 12 months after treatment: 0.77 and 0.75, respectively (p > 0.05). After 1 month, the scores did not change significantly over time (p > 0.05). The intraclass correlation coefficient between changes over time in the HUI3 and EQ-5D scores was 0.30, with other health-related quality-of-life (HRQoL) measures the correlations for HUI3 and EQ-5D were very similar. In conclusion, both the HUI3 and EQ-5D demonstrated an effect of treatment in patients with intermittent claudication; in addition, they showed similar relationships with other (HRQoL) measures. To demonstrate the effect of revascularization in patients with intermittent claudication, however, clinicians and researchers should be aware of the differences in the mean HUI3 and EQ-5D scores. This revised version was published online in June 2006 with corrections to the Cover Date.     

Comparing Short Form 6D,Standard Gamble,and Health Utilities Index Mark 2 and Mark 3 utility scores: Results from total hip arthroplasty patients

Objective: The objectives are to compare SF-6D, standard gamble (SG), and Health Utilities Index (HUI) utility scores, compare change scores, and compare responsiveness. Methods: A cohort of osteoarthritis patients referred for total hip arthroplasty (THA) were evaluated at the time of referral and followed until 3months after THA. Patients were assessed using the SF-36, HUI2, HUI3, and the SG. Agreement is assessed using the intra-class correlation (ICC). Responsiveness is assessed using effect size, standardized response mean, and paired t-test. Results: Data was available for 86 patients at baseline and for 63 at both pre- and post-surgery. At baseline mean SF-6D (0.61), SG (0.62), and HUI2 (0.62) scores were similar; the mean HUI3 score (0.52) was lower. Standard deviations were 0.10, 0.32, 0.19, and 0.22. At baseline, agreement between SF-6D and SG scores was 0.13, agreement between SF-6D and HUI2 was 0.47, and agreement between SF-6D and HUI3 was 0.28. Agreement at pre- and post-surgery was similar. The change in scores between post- and pre-surgery was 0.10 for SF-6D, 0.16 for SG, 0.22 for HUI2, and 0.23 for HUI3. Effect sizes were 1.10 for HUI2, 1.08 for HUI3, 1.06 for SF-6D, and 0.48 for the SG. Conclusions: Agreement between SG scores and SF-6D and HUI scores was low. The estimate of change in utility associated with THA was lowest for SF-6D. Additional longitudinal studies to compare utility measures appear to be warranted.     

Are indirect utility measures reliable and responsive in rheumatoid arthritis patients?

Background: Preference-based, generic measures are increasingly being used to measure quality of life and as sources for quality weights in the estimation of Quality Adjusted Life Years (QALYs) in rheumatoid arthritis (RA). However, among the most commonly used instruments (the Health Utilities Index 2 and 3 [HUI2 and HUI3], the EuroQoL-5D [EQ-5D], and the Short Form-6D [SF-6D], there has been little comparative research. Therefore, we examined the reliability and responsiveness of these measures and the Rheumatoid Arthritis Quality of Life (RAQoL) and the Health Assessment Questionnaire (HAQ) in a sample of RA patients. Major findings: Test–retest reliability was acceptable for all of the instruments with the exception of the EQ-5D. Using two external criteria to define change (a patient transition question and categories of the patient global assessment of disease activity VAS), the RAQoL was the most responsive of the instruments. For the indirect utility instruments, the HUI3 and the SF-6D were the most responsive for measuring positive change. On average, for patients whose RA improved, the absolute change was highest for the HUI3. Conclusions: The HUI3 and the SF-6D appear to be the most responsive of the preference-based instruments in RA. However, differences in the magnitude of the absolute change scores have important implications for cost-effectiveness analyses.     

A view from the bridge: agreement between the SF-6D utility algorithm and the Health Utilities Index

BACKGROUND: The SF-6D is a new health state classification and utility scoring system based on 6 dimensions ('6D') of the Short Form 36, and permits a "bridging" transformation between SF-36 responses and utilities. The Health Utilities Index, mark 3 (HUI3) is a valid and reliable multi-attribute health utility scale that is widely used. We assessed within-subject agreement between SF-6D utilities and those from HUI3. METHODS: Patients at increased risk of sudden cardiac death and participating in a randomized trial of implantable defibrillator therapy completed both instruments at baseline. Score distributions were inspected by scatterplot and histogram and mean score differences compared by paired t-test. Pearson correlation was computed between instrument scores and also between dimension scores within instruments. Between-instrument agreement was by intra-class correlation coefficient (ICC). RESULTS: SF-6D and HUI3 forms were available from 246 patients. Mean scores for HUI3 and SF-6D were 0.61 (95% CI 0.60-0.63) and 0.58 (95% CI 0.54-0.62) respectively; a difference of 0.03 (p<0.03). Score intervals for HUI3 and SF-6D were (-0.21 to 1.0) and (0.30-0.95). Correlation between the instrument scores was 0.58 (95% CI 0.48-0.68) and agreement by ICC was 0.42 (95% CI 0.31-0.52). Correlations between dimensions of SF-6D were higher than for HUI3. CONCLUSIONS: Our study casts doubt on the whether utilities and QALYs estimated via SF-6D are comparable with those from HUI3. Utility differences may be due to differences in underlying concepts of health being measured, or different measurement approaches, or both. No gold standard exists for utility measurement and the SF-6D is a valuable addition that permits SF-36 data to be transformed into utilities to estimate QALYs. The challenge is developing a better understanding as to why these classification-based utility instruments differ so markedly in their distributions and point estimates of derived utilities.     

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.     

Assessing Differences in Utility Scores: A Comparison of Four Widely Used Preference-Based Instruments

OBJECTIVES: To characterize the differences in utility scores (dUTY) among four commonly used preference-based Health-Related Quality of Life instruments, to evaluate the potential impact of these differences on cost-utility analyses (CUA), and to determine if sociodemographic/clinical factors influenced the magnitude of these differences. METHODS: Consenting adult Chinese, Malay and Indian subjects in Singapore were interviewed using Singapore English, Chinese, Malay or Tamil versions of the EQ-5D, Health Utilities Index Mark 2 (HUI2) and Mark 3 (HUI3), and SF-6D. Agreement between instruments was assessed using Bland-Altman (BA) plots. Changes in incremental cost-utility ratio (ICUR) from dUTY were investigated using eight hypothetical decision trees. The influence of sociodemographic/clinical factors on dUTY between instrument pairs was studied using multiple linear regression (MLR) models for English-speaking subjects (circumventing structural zero issues). RESULTS: In 667 subjects (median age 48 years, 59% female), median utility scores ranged from 0.80 (95% confidence interval [CI] 0.80, 0.85) for the EQ-5D to 0.89 (95% CI 0.88, 0.89) for the SF-6D. BA plots: Mean differences (95% CI) exceeded the clinically important difference (CID) of 0.04 for four of six pairwise comparisons, with the exception of the HUI2/EQ-5D (0.03, CI: 0.02, 0.04) and SF-6D/HUI2 (0.02, CI: 0.006, 0.02). Decision trees: The ICER ranged from $94,661/QALY (quality-adjusted life-year; 6.3% difference from base case) to 100,693 dollars/QALY (0.3% difference from base case). MLR: Chronic medical conditions, marital status, and Family Functioning Measures scores significantly (P-value < 0.05) influenced dUTY for several instrument pairs. CONCLUSION: Although CIDs in utility measurements were present for different preference-based instruments, the impact of these differences on CUA appeared relatively minor. Chronic medical conditions, marital status, and family functioning influenced the magnitude of these differences.     

Choosing between measures: comparison of EQ-5D,HUI2 and HUI3 in persons with hearing complaints

Objectives To generate insight into the differences between utility measures EuroQol 5D (EQ-5D), Health Utilities Index Mark II (HUI2) and Mark III (HUI3) and their impact on the incremental cost-effectiveness ratio (ICER) for hearing aid fitting Methods Persons with hearing complaints completed EQ-5D, HUI2 and HUI3 at baseline and, when applicable, after hearing aid fitting. Practicality, construct validity, agreement, responsiveness and impact on the ICER were examined. Results All measures had high completion rates. HUI3 was capable of discriminating between clinically distinctive groups. Utility scores (n = 315) for EQ-5D UK and Dutch tariff (0.83; 0.86), HUI2 (0.77) and HUI3 (0.61) were significantly different, agreement was low to moderate. Change after hearing aid fitting (n = 70) for HUI2 (0.07) and HUI3 (0.12) was statistically significant, unlike the EQ-5D UK (0.01) and Dutch (0.00) tariff. ICERs varied from €647,209/QALY for the EQ-5D Dutch tariff to €15,811/QALY for HUI3. Conclusion Utility scores, utility gain and ICERs heavily depend on the measure that is used to elicit them. This study indicates HUI3 as the instrument of first choice when measuring utility in a population with hearing complaints, but emphasizes the importance of a clear notion of what constitutes utility with regard to economic analyses.     

Not all "quality-adjusted life years" are equal

BACKGROUND: There is evidence that utility elicitation methods used in the calculation of quality-adjusted life years (QALYs) yield different results. It is not clear how these differences impact economic evaluations. METHODS: Using a mathematical model incorporating data on efficacy, costs, and utility values, we simulated the experiences of 100,000 hypothetical rheumatoid arthritis patients over 10 years (50,000 exposed to infliximab plus methotrexate [MTX] and 50,000 exposed to MTX alone). QALYs, were derived from the Health Utilities Index 2 and 3 (HUI2 and HUI3), the Short Form 6-D (SF-6D), and the Euroqol 5-D (EQ-5D). Incremental cost-utility ratios were determined using each instrument to calculate QALYs and the results were compared using cost-effectiveness acceptability curves. RESULTS: Using the different utility measurement methods, the mean difference in QALYs between the infliximab plus MTX and MTX groups ranged from a high of 1.95 QALYs (95% CI=1.93-1.97) using the HUI3 to 0.89 QALYs (95% CI=0.88-0.91) using the SF-6D. Adopting the commonly cited value of society's willingness to pay for a QALY of $50,000, 91% of the simulations favored the cost utility of infliximab plus MTX when using the HUI3 to calculate QALYs. However, when using the EQ-5D, HUI2, or the SF-6D utility values to calculate QALYS, the proportion of simulations that favored the cost utility of infliximab were 63%, 45%, and 12%, respectively. CONCLUSION: Depending on the method for determining utility values used in the calculation of QALYs, very different incremental cost-utility ratios are generated.     

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.     

Evidence on the longitudinal construct validity of major generic and utility measures of health-related quality of life in teens with depression

Purpose

To examine the longitudinal construct validity in the assessment of changes in depressive symptoms of widely used utility and generic HRQL instruments in teens.

Methods

392 teens enrolled in the study and completed HRQL and diagnostic measures as part of the baseline interview. HRQL measures included EuroQol (EQ-5D-3L), Health Utilities Index Mark 2 (HUI2) and Mark 3 (HUI3), Quality of Well-Being Scale (QWB), Pediatric Quality of Life Inventory (PEDS-QL), RAND-36 (SF-6D), and Quality of Life in Depression Scale (QLDS). Youth completed follow-up interviews 12 weeks after baseline. Sixteen youth (4.1%) were lost to follow-up. We examined correlations between changes in HRQL instruments and the Children’s Depression Rating Scale-Revised (CDRS-R) and assessed clinically meaningful change in multi-attribute utility HRQL measures using mean change (MC) and standardized response mean (SRM) among youth showing at least moderate (20%) improvement in depression symptomology.

Results

Spearman’s correlation coefficients demonstrated moderate correlation between changes in CDRS-R and the HUI2 (r?=?0.38), HUI3 (r?=?0.42), EQ-5D-3L (r?=?0.36), SF-6D (r?=?0.39), and PEDS-QL (r?=?0.39) and strong correlation between changes in CDRS-R and QWB (r?=?0.52) and QLDS (r?=???0.71). Effect size results are also reported. Among multi-attribute utility measures, all showed clinically meaningful improvements in the sample of youth with depression improvement (HUI2, MC?=?0.20, SRM?=?0.97; HUI3, MC?=?0.32, SRM?=?1.17; EQ-5D-3L, MC?=?0.08, SRM?=?0.51; QWB, MC?=?0.11, SRM?=?0.86; and SF-6D, MC?=?0.12, SRM?=?1.02).

Conclusions

Findings support the longitudinal construct validity of included HRQL instruments for the assessment of change in depression outcomes in teens. Results of this study can help inform researchers about viable instruments to include in economic evaluations for this population.

     

Utility-based Quality of Life Measures in Alzheimer’s Disease

Objectives: To explore whether Alzheimer’s disease patients could rate their quality of life (QOL) using utility-based health indexes, and to provide new knowledge about the measurement properties of these instruments for patient and caregiver proxy ratings. Methods: A convenience sample of 60 mild-moderate AD patients and their caregivers were randomized to complete the Quality of Well-Being Scale (QWB), Health Utilities Index (HUI3) or EQ-5D and visual analogue scale (VAS) on two occasions. Test–retest reliability (intraclass correlation coefficients) and convergent validity (Spearman correlations) of utility scores with global health status, activities of daily living, comorbidity, mood, cognition and other utility measures were assessed. Results: Completion time was shortest for the combined EQ-5D and VAS. For patients with mild dementia and for proxies, reliability was ≥ 0.70 for the EQ-5D, QWB and HUI3. The EQ-5D had a ceiling effect for patient ratings. Convergent validity was demonstrated for patient and proxy ratings, with the strongest validity for EQ-5D ratings and the weakest validity for HUI3 patient ratings. Mean patient utility scores were significantly higher than mean proxy scores for all measures (p<0.001). Conclusions: For patient and proxy ratings, the EQ-5D had the best combination of measurement properties, although it had a substantial ceiling effect for patient ratings. Proxy QOL ratings did not accurately reflect patients’ ratings.     

A comparison of the performance of the EQ-5D and SF-6D for individuals aged >or= 45 years

We sought to compare the performance of the EQ-5D and SF-6D with regard to the criteria of practicality, convergent validity, and construct validity, the level of agreement between the two measures was also assessed. Responses from 1865 individuals aged >or= 45 years in one general practice were analysed. Of these, 93.1% completed the EQ-5D, compared with 86.4% for the SF-6D, where individuals who were older, female, of a lower occupational skill level, from an area of lower deprivation, or used prescribed medication were significantly less likely to complete the SF-6D. The performance of both measures was comparable with regard to both convergent and construct validities, as both the EQ-5D and SF-6D scores were closely related to scores on the EuroQol visual analogue scale (VAS) (p<0.001) and able to discriminate between people who did and did not take: (i) analgesics and (ii) other prescribed medication. Despite EQ-5D and SF-6D scores being highly correlated (p<0.001), individuals who were healthier (according to the VAS) had higher mean scores on the EQ-5D (p<0.001), whereas less healthy individuals had higher mean scores on the SF-6D (individuals with knee pain, osteoarthritis, back pain, rheumatoid arthritis, and hip pain had significantly lower mean scores on the EQ-5D, p<0.001).     

Validation and Comparison of EuroQol and Short Form 6D in Chronic Prostatitis Patients

ObjectiveGeneric, preference-based health-related quality of life (HRQoL) instruments is increasingly used in health-care decision-making process. However, to our knowledge, no such HRQoL instrument has been validated or used in chronic prostatitis. We therefore aimed to assess and compare the psychometric properties of EuroQol (EQ-5D) and Short Form 6D (SF-6D) among chronic prostatitis patients in China.MethodsConsenting patients were interviewed using EQ-5D and SF-6D. Convergent and discriminative construct validities were examined with five and two a priori hypotheses, respectively. Sensitivity was compared using receiver operating characteristic (ROC) curves and relative efficiency (RE) statistics. Agreement between instruments was assessed with intra-class correlation coefficients and Bland–Altman plot, while factors affecting utility difference were explored with multiple liner regression models.ResultsIn 268 subjects, mean (SD) EQ-5D and SF-6D utility scores were comparable at 0.73 (0.15) and 0.75 (0.10), respectively. Five of the seven hypotheses for construct validity were fulfilled in both instruments. The areas under ROC of them all exceeded 0.5 (P < 0.001). SF-6D had 9.7–19.9% higher efficiency than EQ-5D at detecting the difference in chronic prostatitis symptom severity. Despite no significant difference in utility scores between two instruments, lack of agreement was observed with low intraclass correlation coefficient (0.218–0.630) and Bland–Altman plot analysis. Chronic prostatitis symptom severity significantly (P < 0.05) influenced differences in utility scores between EQ-5D and SF-6D.ConclusionsBoth EQ-5D and SF-6D are demonstrated to be valid and sensitive HRQoL measures in Chinese chronic prostatitis patients, with SF-6D showing better HRQoL dimension coverage, greater sensitivity, lower ceiling effect, and more rational distribution. Further research is needed to determine longitudinal response and reliability.     

Comparison of three societally derived health-state classification values among older African Americans with depressive symptoms

Purpose

To compare societal values across three health-state classification systems in older African Americans with depression and to describe the association of these instruments to depression severity.

Methods

We summarized baseline values for EQ-5D (US weights) and HUI2/3 (Canadian weights) and their subscales for 118 older African American participants enrolled in a randomized depression treatment trial and calculated correlations between the different instruments. We evaluated ceiling and floor effects for each instrument by comparing the proportion at the highest and lowest possible score for each tool. Also, utility scores were assessed by level of depression severity (mild, moderate, moderate severe, severe) scores as measured by the Patient Health Questionnaire (PHQ-9).

Results

Mean utility values were 0.58 (SD = 0.21) for EQ-5D, 0.52 (SD = 0.21) for HUI2, and 0.36 (SD = 0.31) for HUI3. For the EQ-5D, 72 % of participants reported having some problems on the anxiety/depression domain. On the emotion domain for the HUI2, 23 % reported the highest level of impairment compared to only 3 % on the HUI3. No participant scored at the floor for the EQ-5D, HUI2, or HUI3 index; one participant scored at the ceiling value on the HUI3 index. Correlations ranged from 0.63 to 0.82 (all of which were significant at an alpha level of 0.05). In general, utility scores trended inversely with depression level.

Conclusion

Small differences in the three preference-weighted health-state classification systems were evident for this sample of older African Americans with depressive symptoms, with HUI scores lower than EQ-5D. For this sample, utility scores were lower (i.e., poorer) than the general United States population with depression on each utility measure.     

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.     

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.     

An assessment of validity and responsiveness of generic measures of health-related quality of life in hearing impairment

Purpose

This review examines psychometric performance of three widely used generic preference-based measures, that is, EuroQol 5 dimensions (EQ-5D), Health Utility Index 3 (HUI3) and Short-form 6 dimensions (SF-6D) in patients with hearing impairments.

Methods

A systematic search was undertaken to identify studies of patients with hearing impairments where health state utility values were measured and reported. Data were extracted and analysed to assess the reliability, validity (known group differences and convergent validity) and responsiveness of the measures across hearing impairments.

Results

Fourteen studies (18 papers) were included in the review. HUI3 was the most commonly used utility measures in hearing impairment. In all six studies, the HUI3 detected difference between groups defined by the severity of impairment, and four out of five studies detected statistically significant changes as a result of intervention. The only study available suggested that EQ-5D only had weak ability to discriminate difference between severity groups, and in four out of five studies, EQ-5D failed to detected changes. Only one study involved the SF-6D; thus, the information is too limited to conclude on its performance. Also evidence for the reliability of these measures was not found.

Conclusion

Overall, the validity and responsiveness of the HUI3 in hearing impairment was good. The responsiveness of EQ-5D was relatively poor and weak validity was suggested by limited evidence. The evidence on SF-6D was too limited to make any judgment. More head-to-head comparisons of these and other preference measures of health are required.