The Correlation Between Body Mass Index and Health-Related Quality of Life: Data from Two Weight Loss Intervention Studies.

INTRODUCTION: The correlation between body mass index (BMI) and utility in participants with obesity was assessed using health-related quality-of-life data collected in two weight loss intervention studies, SCALE and STEP 1. METHODS: Short Form Health Survey 36-Item (SF-36) scores from SCALE and STEP 1 were mapped to EuroQoL-5 dimensions-3 levels (EQ-5D-3L) using an established algorithm to derive utilities for the UK. SF-36 scores from STEP 1 were converted into Short Form 6 dimension (SF-6D) utilities for Portugal using the tool developed by the University of Sheffield. The correlation between baseline BMI and utility was assessed by multiple linear regression analyses, controlling for demographic and clinical parameters. RESULTS: A higher baseline BMI correlated with lower EQ-5D-3L and SF-6D utilities, although the trend was non-significant. Assuming linearity between BMI ranges 30-40 kg/m2, an additional unit of BMI correlated with 0.0041 and 0.0031 lower EQ-5D-3L scores in SCALE and 0.0039 and 0.0047 lower EQ-5D-3L and 0.0027 and 0.0020 lower SF-6D scores in STEP 1 for men and women, respectively. CONCLUSION: In individuals with comparable demographic characteristics and weight-related comorbidities, a 1 unit change in BMI leads to a difference of up to 0.005 in utility indices. TRIAL REGISTRATION: ClinicalTrials.gov identifiers: SCALE (NCT01272219) and STEP 1 (NCT03548935).

Cost-effectiveness analyses compare health benefits and costs between treatments to inform decisions on healthcare resource allocation. Health benefits are typically quantified as quality-adjusted life-years (QALYs) gained. The calculation of QALYs relies on health-related quality-of-life (HRQoL) data, which are collected from participants. However, to allow comparisons across multiple interventions and diseases, HRQoL needs to be converted into a standardized, generic measure, i.e., a utility index ranging from 0 (equivalent to death) to 1 (perfect health). In this study, HRQoL data from the SCALE and STEP 1 clinical trials were converted into utility indexes and analyzed against participants' weight at study start, expressed as body mass index (BMI, kg/m²). Our study indicates that there is a negative correlation between BMI and health utility at a population level whereby an additional unit of BMI, within the range of 30­40 kg/m², was consistently correlated with an up to 0.005 worsening in the utility index across men and women. The estimated effect size was small, indicating that BMI alone may not explain the differences in participants' HRQoL and general population evaluation of these.

Comparing EQ-5D-5L, PROPr, SF-6D and TTO utilities in patients with chronic skin diseases.

OBJECTIVES: We aim to compare the measurement properties of three indirect (EQ-5D-5L, PROPr, SF-6D) and one direct (time trade-off, TTO) utility assessment methods in patients with chronic skin diseases. METHODS: 120 patients with physician-diagnosed chronic skin diseases (psoriasis 39%, atopic dermatitis 27%, acne 19%) completed a cross-sectional survey. Respondents completed the EQ-5D-5L, PROMIS-29+2 and SF-36v1 questionnaires and a 10-year TTO task for own current health. Utilities were computed using the US value sets. Ceiling, convergent and known-group validity were compared across the utilities derived with these four methods. Known-groups were defined based on general, physical and mental health. The agreement between utilities was assessed using intraclass correlation coefficients (ICC). RESULTS: Mean utilities for the EQ-5D-5L, PROPr, SF-6D and TTO were 0.79, 0.47, 0.76 and 0.89. In corresponding order, the ceiling was 28%, 0%, 2% and 65%. The SF-6D showed excellent agreement with the EQ-5D-5L (ICC = 0.770). PROPr demonstrated poor agreement with the EQ-5D-5L (ICC = 0.381) and fair with SF-6D utilities (ICC = 0.445). TTO utilities showed poor agreement with indirectly assessed utilities (ICC = 0.058-0.242). The EQ-5D-5L better discriminated between known groups of general and physical health, while the SF-6D and PROPr outperformed the EQ-5D-5L for mental health problems. CONCLUSION: There is a great variability in utilities across the four methods in patients with chronic skin conditions. The EQ-5D-5L, despite its higher ceiling, appears to be the most efficient in discriminating between patient groups for physical health aspects. Our findings inform the choice of instrument for quality-adjusted life year calculations in cost-utility analyses.

Estimating Utility Values for Health States of Nigerian Individuals with Stroke or Epilepsy Using the SF-36: A Brief Report on the Results of a Cross-Sectional Survey.

Background. Stroke and epilepsy are the most common neurologic conditions affecting individuals. The Short Form Six-Dimension Health Index (SF-6D) is a preference-based measure of health developed to estimate utility values from the SF-36. This study estimated utility values for health states of Nigerian individuals with stroke or epilepsy using the SF-36. Methods. SF-36 responses from 125 and 69 individuals with stroke and persons with epilepsy, respectively, were transformed into health state utility values using the SF-6D algorithm. The Excel program developed by Brazier and colleagues was used to generate the SF-6D utility score estimated using a set of parametric preference weights. The health state utility values were determined using ordinal health state and standard gamble valuation techniques. Results. Mean (s) ages of the stroke and epilepsy participants were 63.1 (11) and 39.6 (16) y, respectively. The mean (s) utility scores for stroke and epilepsy were 0.52 (0.10) and 0.65 (0.1) for standard gamble and 0.48 (0.13) and 0.68 (0.11), respectively, using the ordinal health state paradigm. The mean (s) utility of stroke (female = 0.46 [0.15]; male = 0.50 [0.12]) and epilepsy (female = 0.65 [0.13], male = 0.69 [0.11]) participants were reported. The mean (s) annual episodes of seizure was 18.7 (39). Conclusions. To our knowledge, this is the first study to suggest that females with stroke and those with epilepsy considered their health to be poorer than that of their male counterparts. The significance of our findings is that they may be helpful for researchers, policy makers, and clinicians by providing input into economic evaluations to facilitate resource allocation for stroke survivors and people living with epilepsy to improve their health outcomes and reduce the huge burden associated with the conditions. Highlight: We estimated a health state utility value for stroke and epilepsy to aid researchers and public health policy makers in conducting health economic analysis and outcomes research.

Creating an SF-6Dv2 social value set for New Zealand.

The SF-6D health descriptive system and its second version published in 2020, the SF-6Dv2, is used worldwide for valuing health-related quality of life (HRQoL) for economic evaluation and measuring patient-reported health outcomes. In this study, a valuation tool was developed and applied to create a social value set, comprising 18,750 health state values, for the SF-6Dv2 for New Zealand (NZ). This tool was adapted and extended from the one used to create a social value set for the EQ-5D-5L, a simpler health descriptive system with fewer dimensions and health states. The tool implements the PAPRIKA method, a type of adaptive discrete choice experiment, and a binary search algorithm to identify health states worse than dead and has extensive data quality controls to ensure the validity and reliability of the social value set derived from participants' personal value sets. The tool, accompanied by a short introductory video designed specifically for the SF-6Dv2, was distributed via an online survey to a large representative sample of adult New Zealanders in June-July 2022. The tool's data quality controls enabled participants who failed to understand or sincerely engage with the valuation tasks to be identified and excluded, resulting in the participants being pared down to a sub-sample of 2985 'high-quality' participants whose personal value sets were averaged for the social value set. These results, including participants' positive feedback, demonstrate the feasibility and acceptability of using the tool to value larger health descriptive systems such as the SF-6Dv2. Having successfully created an SF-6Dv2 social value set for NZ, the valuation tool can be readily applied to other countries, used to generate personal value sets for personalised medicine and adapted to create value sets for other health descriptive systems.

On the ability of the SF-6D to capture the consequences of chronic illnesses on subjective well-being: Evidence from France.

Using cross-sectional data from a representative sample of the French population (the 2008 Disability Health survey), this paper examines whether the SF-6D, a widely used preference-based measure of health-related quality of life in economic evaluations, fully captures the variation in subjective well-being (SWB) due to chronic illnesses. We conduct a mediation analysis to disentangle the direct and indirect, through the SF-6D, effects of various chronic conditions on SWB (happiness). Our results show that the SF-6D reflects changes in happiness due to most illnesses except mental illness. Changes in SWB mediated by the SF-6D account for 74% of the total effect. The variation unexplained by the SF-6D is significant and increases substantially in the presence of multimorbidity when a chronic illness is combined with anxiety or depression. Overall, our results suggest that the SF-6D incompletely captures the subjective experience of chronically ill patients, especially those with comorbid conditions.

Measurement properties of the EQ-5D-3L, EQ-5D-5L, and SF-6Dv2 in patients with late-onset Pompe disease.

OBJECTIVE: The objective of this study was to evaluate the psychometric properties of the EQ-5D (3L and 5L) and SF-6Dv2 in a group of Chinese patients with late-on Pompe disease (PD), and compare their performance in this patient group. METHODS: The data used in this study were obtained from a web-based and cross-sectional survey conducted in China. All participants completed the 3L, 5L, and SF-6Dv2. Information about their sociodemographic status and health conditions was also collected. The measurement properties were assessed by examining ceiling and floor effects, evaluating convergent validity, known-group validity, and test-retest reliability (Intraclass correlation coefficient [ICC] and Gwet's AC). RESULTS: A total of 117 PD patients completed the questionnaire. All dimensions of the 3L showed strong ceiling effects, ranging between 17.1 and 42.7%. All three measures showed good test-retest reliability, with ICC values ranging from 0.85 to 0.87. The Gwet's AC values showed that four out of five dimensions of the 3L showed very good agreement. All hypothesized correlations between the 3L, 5L, SF-6Dv2, and items of WHODAS were supported, indicating satisfactory convergent validity. The 5L showed stronger correlations (|r|= 0.53-0.84) with WHODAS than the other two measures. The outcomes of ANOVA indicated that the 5L had higher F-statistics than the 3L and SF-6Dv2, indicating a stronger discriminant ability to differentiate most condition groups. CONCLUSION: The 5L demonstrates lower ceiling and floor effects, higher discriminant ability, and better convergent validity than the SF-6Dv2 and 3L in patients with PD. In addition, the 5L may generate a larger utility gain compared to the other two instruments when conducting cost-effectiveness analysis.

A Spanish value set for the SF-6D based on the SF-12 v1.

AIM: This paper reports the first estimation of an SF-6D value set based on the SF-12 for Spain. METHODS: A representative sample (n = 1020) of the Spanish general population valued a selection of 56 hypothetical SF-6D health states by means of a probability lottery equivalent (PLE) method. The value set was derived using both random effects and mean models estimated by ordinary least squares (OLS). The best model was chosen on the basis of its predictive ability assessed in terms of mean absolute error (MAE). RESULTS: The model yielding the lowest MAE (0.075) was that based on main effects using OLS. Pain was the most significant dimension in predicting health state severity. Comparison with the previous SF-6D (SF-36) model estimated for Spain revealed no significant differences, with a similar MAE (0.081). Nevertheless, the new SF-6D (SF-12) model predicted higher utilities than those generated by the SF-6D (SF-36) scoring algorithm (minimum value - 0.071 vs - 0.357). CONCLUSION: A value set for the SF-6D (SF-12) based on Spanish general population preferences elicited by means of a PLE technique is successfully estimated. The new estimated SF-6D (SF-12) preference-based measure provides a valuable tool for researchers and policymakers to assess the cost-effectiveness of new health technologies in Spain.

Psychometric performance of the CFQ-R-8D compared to the EQ-5D-3L and SF-6D in people with cystic fibrosis.

OBJECTIVE: This study aimed to compare the psychometric performance of the Cystic Fibrosis Questionnaire-Revised-8 Dimensions (CFQ-R-8D), a new, condition-specific, preference-based measure, with that of generic preference-based measures EQ-5D-3L and Short Form 6 dimensions (SF-6D). METHODS: Data from three trials of participants with CF aged ≥ 14 years who completed the CFQ-R and EQ-5D-3L or SF-6D were used. Analyses were undertaken to evaluate convergent validity based on correlations with CFQ-R domain scores. Known-group validity was assessed based on percent predicted forced expiratory volume in one second and pulmonary exacerbations. Responsiveness was based on correlation of change and sensitivity to change based on change in symptom severity. Effect sizes and standardized response means were estimated. RESULTS: CFQ-R-8D utilities and dimensions were strongly correlated with most of the overlapping CFQ-R domain scores (ρ > 0.5); EQ-5D-3L and SF-6D utilities and dimensions had moderate (ρ > 0.3) to strong correlations in dimensions capturing similar concepts. All measures showed evidence of known-group validity (P < 0.05). Change correlations were strong for CFQ-R-8D utilities and dimensions and CFQ-R, but they were moderate for SF-6D and mostly weak ((ρ > 0.1) for EQ-5D-3L. The SF-6D had the largest mean change over time and effect sizes, followed by CFQ-R-8D and then EQ-5D-3L. Neither CFQ-R-8D or SF-6D utility scores had ceiling effects (< 9% responses in full health) compared with those of EQ-5D-3L (61-62%). In participants classified as being in full health by EQ-5D-3L, CFQ-R-8D captured CF-specific health problems, particularly cough, abdominal pain, and breathing difficulty. CONCLUSIONS: The CFQ-R-8D reflected known-group differences and changes over time with stronger evidence of good psychometric performance than EQ-5D-3L and similar evidence as SF-6D. Additionally, the CFQ-R-8D captured more condition-specific symptoms than EQ-5D-3L or SF-6D, which are important determinants of health-related quality of life for people with CF.

SF-6D Normative Values Among Patients Undergoing Bariatric Surgery: Results Based on Real-World Evidence from the Scandinavian Obesity Surgery Registry (SOReg).

BACKGROUND: The SF-6D index can be used to calculate quality-adjusted life years in economic evaluations, which is required by reimbursement agencies and national advisory bodies, including the Swedish ones. However, despite that SF-36 has been largely applied among patients undergoing bariatric surgery, almost no study has accessed the short form six-dimensions (SF-6D) after bariatric surgery. AIM: To establish normative values for the SF-6D index among patients undergoing bariatric surgery. MATERIALS AND METHODS: All patients who received bariatric surgery in Sweden between 2011-01-01 and 2019-03-31 were obtained from the Scandinavian Obesity Surgery Registry (SOReg). Information includes patients' sociodemographic characteristics, details regarding the procedure, and postsurgical conditions. The SF-36 is applied at baseline and at follow-up years 1, 2, and 5. The multiple sequential imputation method was applied to handle missingness on SF-6D items. Based on the UK tariff, the SF-6D preference scores were calculated. The normative values for the mean (SD) SF-6D index were reported by timepoint and surgical complications for men and women, respectively. Multivariate analyses were applied to investigate how the SF-6D index is associated with timepoint, controlling for age, sex, BMI, and comorbidities in a stepwise manner. RESULTS: The SF-6D index increased at 1 year relative to baseline and was roughly maintained at the same level at 2 years. The normative value of the SF-6D index can be used in economic evaluations for bariatric surgery.

A comparative study of Chinese medicine quality of life assessment scale (CQ-11D) and EQ-5D-5L and SF-6D scales based on Chinese population.

PURPOSE: To measure health-related quality of life in the Chinese population using three universal health utility scales (CQ-11D, EQ-5D-5L, and SF-6D) and to compare the differences in the results obtained by the different scales to provide a reference for future utility on health-related quality of life in the Chinese population. METHODS: According to the Chinese population's distribution area, gender, and age, quota sampling was conducted. Three scales, CQ-11D, EQ-5D-5L, and SF-6D, whose results were self-reported, were collected in succession after collecting respondents' demographic information. The health utility value and floor/ceiling effect were explained. Bland-Altman was used to evaluate the consistency, the intraclass correlation coefficient was used to evaluate the correlation, and the receiver operating characteristic curve was used to evaluate the discriminative validity of the scale. RESULTS: The mean utility values of the CQ-11D, EQ-5D-5L, and SF-6D scales, respectively, were 0.891, 0.927, and 0.841. The floor effect did not appear in any of the three scales, but the ceiling effect did, and the EQ-5D-5L ceiling effect was the most severe. The limits of the agreement interval for CQ-11D versus EQ-5D-5L in the total sample population were (-0.245,0.172); for CQ-11D versus SF-6D, they were (- 0.256,0.354); and for EQ-5D-5L versus SF-6D, they were (-0.199,0.371). The consistency of the three scales is satisfactory overall. In the total population, the intraclass correlation coefficient between CQ-11D and EQ-5D-5L was 0.709, while EQ-5D-5L and SF-6D were 0.0.565 and that between EQ-5D-5L and SF-6D was 0.472. According to the subject operation curve results, the area under the curve for the total sample population of CQ-11D was 0.746, EQ-5D-5L was 0.669, and SF-6D was 0.734. CONCLUSION: The CQ-11D is inferior to the EQ-5D-5L, but superior to the SF-6D. There is a strong correlation between the health utility values of the total population as measured by the three scales and those of the healthy population. The CQ-11D scale is the most sensitive to differences between populations and diseases.

Mapping the EORTC QLQ-C30 and QLQ H&N35 to the EQ-5D-5L and SF-6D for papillary thyroid carcinoma.

PURPOSE: Empirical evidence for the EORTC QLQ C30 scale in thyroid cancer mapping algorithms has not been found in China, which limits the cost-utility analysis of patients with papillary thyroid carcinoma (PTC) population. We developed mapping algorithms that use the EORTC QLQ-C30 and QLQ H&N35 to predict EQ-5D-5L and SF-6D health utility scores for PTC patients. METHODS: Data from 1050 Chinese PTC patients who completed the EORTC QLQ-C30, QLQ H&N35, EQ-5D-5L and SF-6D instruments were collected. Direct mapping (OLS, Tobit, Betamix) and indirect mapping functions (Order Probit) were used to estimate algorithms. The goodness-of-fit of mapping performance was assessed by MAE, RMSE, AIC, BIC, AE, and ICC. A fivefold cross-validation and random sample validation approach were used to test the stability of the models. RESULTS: The mean EQ-5D-5L and SF-6D utility scores were 0.8704 and 0.6368, respectively. We recommend the Betamix model for the EQ-5D-5L (MAE = 0.0363, RMSE = 0.0505, AIC = -3458.73, BIC = -3096.91, AE > 0.05(%) = 48.38, AE > 0.1(%) = 8.67, ICC = 0.8288 for the full sample dataset) and the Betamix model for the SF-6D (MAE = 0.0328, RMSE = 0.0417, AIC = -2788.91, BIC = -2605.51, AE > 0.05(%) = 42.76, AE > 0.1(%) = 3.62, ICC = 0.8657 for the full sample dataset), with EORTC QLQ-C30 all items, QLQ H&N35 all items, age and gender as the predicted variables showing the best performance. CONCLUSION: In the absence of preference-based quality of life tools, the mapping algorithms reported here are effective alternative for predicting the health utility of PTC patients, contributing to the cost-utility analysis studies.

Comparative performance and mapping algorithms between EQ-5D-5L and SF-6Dv2 among the Chinese general population.

OBJECTIVES: To explore the comparative performance and develop the mapping algorithms between EQ-5D-5L and SF-6Dv2 in China. METHODS: Respondents recruited from the Chinese general population completed both EQ-5D-5L and SF-6Dv2 during face-to-face interviews. Ceiling/floor effects were reported. Discriminative validity in self-reported chronic conditions was investigated using the effect sizes (ES). Test-retest reliability was evaluated using intra-class correlation coefficient (ICC) and Bland-Altman plots in a subsample. Correlation and absolute agreements between the two measures were estimated with Spearman's rank correlation coefficient and ICC, respectively. Ordinary least squares (OLS), generalized linear model, Tobit model, and robust MM-estimator were explored to estimate mapping equations between EQ-5D-5L and SF-6Dv2. RESULTS: 3320 respondents (50.3% males; age 18-90 years) were recruited. 51.1% and 12.2% of respondents reported no problems on all EQ-5D-5L and SF-6Dv2 dimensions, respectively. The mean EQ-5D-5L utility was higher than SF-6Dv2 (0.947 vs. 0.827, p < 0.001). Utilities were significantly different across all chronic conditions groups for both measures. The mean absolute difference of utilities between the two tests for EQ-5D-5L was smaller (0.033 vs. 0.043) than SF-6Dv2, with a slightly higher ICC (0.859 vs. 0.827). Fair agreement (ICC = 0.582) was observed in the utilities between the two measures. Mapping algorithms generated by the OLS models performed the best according to the goodness-of-fit indicators. CONCLUSIONS: Both measures showed comparable discriminative validity. Systematic differences in utilities were found, and on average, the EQ-5D-5L generates higher values than the SF-6Dv2. Mapping algorithms between the EQ-5D-5L and SF-6Dv2 are reported to enable transformations between these two measures in China.

Prediction of the SF-6D utility score from Lung cancer FACT-L: a mapping study in China.

OBJECTIVE: To develop a mapping algorithm for generating the Short Form Six-Dimension (SF-6D) utility score based on the Functional Assessment of Cancer Therapy-Lung (FACT-L) of lung cancer patients. METHODS: Data were collected from 625 lung cancer patients in mainland China. The Spearman rank correlation coefficient and principal component analysis were used to evaluate the conceptual overlap between the FACT-L and SF-6D. Five model specifications and four statistical techniques were used to derive mapping algorithms, including ordinary least squares (OLS), Tobit and beta-mixture regression models, which were used to directly estimate health utility, and ordered probit regression was used to predict the response level. The prediction performance was evaluated using the correlations between the root mean square error (RMSE), mean absolute error (MAE), concordance correlation coefficient (CCC), Akaike information criterion (AIC) and Bayesian information criterion (BIC) and the observed and predicted SF-6D scores. A five-fold cross-validation method was used to test the universality of each model and select the best model. RESULTS: The average FACT-L score was 103.024. The average SF-6D score was 0.774. A strong correlation was found between FACT-L and SF-6D scores (ρ = 0.797). The ordered probit regression model with the total score of each dimension and its square term, as well as age and sex as covariates, was most suitable for mapping FACT-L to SF-6D scores (5-fold cross-validation: RMSE = 0.0854; MAE = 0.0655; CCC = 0.8197; AEs > 0.1 (%) = 53.44; AEs > 0.05 (%) = 21.76), followed by beta-mixture regression for direct mapping. The Bland‒Altman plots showed that the ordered probit regression M5 had the lowest proportion of prediction scores outside the 95% agreement limit (-0.166, 0.163) at 4.96%. CONCLUSIONS: The algorithm reported in this paper enables lung cancer data from the FACT-L to be mapped to the utility of the SF-6D. The algorithm allows the calculation of quality-adjusted life years for cost-utility analyses of lung cancer.

Obtaining SF-6D utilities from FACT-H&N in thyroid carcinoma patients: development and results from a mapping study.

Objective: There is limited evidence for mapping clinical tools to preference-based generic tools in the Chinese thyroid cancer patient population. The current study aims to map the FACT-H&N (Functional Assessment of Cancer Therapy-Head and Neck Cancer) to the SF-6D (Short Form Six-Dimension), which will inform future cost-utility analyses related to thyroid cancer treatment. Methods: A total of 1050 participants who completed the FACT-H&N and SF-6D questionnaires were included in the analysis. Four methods of direct and indirect mapping were estimated: OLS regression, Tobit regression, ordered probit regression, and beta mixture regression. We evaluated the predictive performance in terms of root mean square error (RMSE), mean absolute error (MAE), concordance correlation coefficient (CCC), Akaike information criterion (AIC) and Bayesian information criterion (BIC) and the correlation between the observed and predicted SF-6D scores. Results: The mean value of SF-6D was 0.690 (SD = 0.128). The RMSE values for the fivefold cross-validation as well as the 30% random sample validation for multiple models in this study were 0.0833-0.0909, MAE values were 0.0676-0.0782, and CCC values were 0.6940-0.7161. SF-6D utility scores were best predicted by a regression model consisting of the total score of each dimension of the FACT-H&N, the square of the total score of each dimension, and covariates including age and gender. We proposed to use direct mapping (OLS regression) and indirect mapping (ordered probit regression) to establish a mapping model of FACT-H&N to SF-6D. The mean SF-6D and cumulative distribution functions simulated from the recommended mapping algorithm generally matched the observed ones. Conclusions: In the absence of preference-based quality of life tools, obtaining the health status utility of thyroid cancer patients from directly mapped OLS regression and indirectly mapped ordered probit regression is an effective alternative.

Estimating the disutility of relapse in relapsing-remitting and secondary progressive multiple sclerosis using the EQ-5D-5L, AQoL-8D, EQ-5D-5L-psychosocial, and SF-6D: implications for health economic evaluation models.

BACKGROUND AND AIMS: Relapses are an important clinical feature of multiple sclerosis (MS) that result in temporary negative changes in quality of life (QoL), measured by health state utilities (HSUs) (disutilities). We aimed to quantify disutilities of relapse in relapsing remitting MS (RRMS), secondary progressive MS (SPMS), and relapse onset MS [ROMS (including both RRMS and SPMS)] and examine these values by disability severity using four multi-attribute utility instruments (MAUIs). METHODS: We estimated (crude and adjusted and stratified by disability severity) disutilities (representing the mean difference in HSUs of 'relapse' and 'no relapse' groups as well as 'unsure' and 'no relapse' groups) in RRMS (n = 1056), SPMS (n = 239), and ROMS (n = 1295) cohorts from the Australian MS Longitudinal Study's 2020 QoL survey, using the EQ-5D-5L, AQoL-8D, EQ-5D-5L-Psychosocial, and SF-6D MAUIs. RESULTS: Adjusted mean overall disutilities of relapse in RMSS/SPMS/ROMS were - 0.101/- 0.149/- 0.129 (EQ-5D-5L), - 0.092/- 0.167/- 0.113 (AQoL-8D), - 0.080/- 0.139/- 0.097 (EQ-5D-5L-Psychosocial), and - 0.116/- 0.161/- 0.130 (SF-6D), approximately 1.5 times higher in SPMS than in RRMS, in all MAUI. All estimates were statistically significant and/or clinically meaningful. Adjusted disutilities of RRMS and ROMS demonstrated a U-shaped relationship between relapse disutilities and disability severity. Relapse disutilities were higher in 'severe' disability than 'mild' and 'moderate' in the SPMS cohort. CONCLUSION: MS-related relapses are associated with substantial utility decrements. As the type and severity of MS influence disutility of relapse, the use of disability severity and MS-type-specific disutility inputs is recommended in future health economic evaluations of MS. Our study supports relapse management and prevention as major mechanisms to improve QoL in people with MS.

Prediction of quality-adjusted life years (QALYs) after bariatric surgery using regularized linear regression models: results from a Swedish nationwide quality register.

PURPOSE: To investigate whether the quality-adjusted life years (QALYs) of the patients who underwent bariatric surgery could be predicted using their baseline information. MATERIALS AND METHODS: All patients who received bariatric surgery in Sweden between January 1, 2011 and March 31, 2019 were obtained from the Scandinavian Obesity Surgery Registry (SOReg). Baseline information included patients' sociodemographic characteristics, details regarding the procedure, and postsurgical conditions. QALYs were assessed by the SF-6D at follow-up years 1 and 2. The general and regularized linear regression models were used to predict postoperative QALYs. RESULTS: All regression models demonstrated satisfactory and comparable performance in predicting QALYs at follow-up year 1, with R2 and relative root mean squared error (RRMSE) values of about 0.57 and 9.6%, respectively. The performance of the general linear regression model increased with the number of variables; however, the improvement was ignorable when the number of variables was more than 30 and 50 for follow-up years 1 and 2, respectively. Although minor L1 and L2 regularization provided better prediction ability, the improvement was negligible when the number of variables was more than 20. All the models showed poorer performance for predicting QALYs at follow-up year 2. CONCLUSIONS: Patient characteristics before bariatric surgery including health related quality of life, age, sex, BMI, postoperative complications within six weeks, and smoking status, may be adequate in predicting their postoperative QALYs after one year. Understanding these factors can help identify individuals who require more personalized and intensive support before, during, and after surgery.

Cognitive impairment and health-related quality of life amongst older Australians: evidence from a longitudinal investigation.

INTRODUCTION: Australia's population is steadily growing older, with older persons expected to make up over 20% of the population by 2066. Ageing is strongly associated with a significant drop in cognitive ability, ranging from mild cognitive impairment to severe cognitive impairment (dementia). This study examined the association between cognitive impairment and health-related quality of life (HRQoL) in older Australians. METHODS: Two waves of longitudinal data from the nationally representative Household, Income and Labour Dynamics in Australia (HILDA) survey were utilised, with the age cut-off for older Australians defined as above 50. The final analysis included 10,737 person-year observations from 6892 unique individuals between 2012 and 2016. This study utilised the Backwards Digit Span (BDS) test and Symbol Digit Modalities test (SDMT) to assess cognitive function. HRQoL was measured using the physical and mental component summary scores of the SF-36 Health Survey (PCS and MCS). Additionally, HRQoL was measured using health state utility values (SF-6D score). A longitudinal random-effects GLS regression model was used to analyse the association between cognitive impairment and HRQoL. RESULTS: This study found that approximately 89% of Australian adults aged 50 or older had no cognitive impairment, 10.16% had moderate cognitive impairment, and 0.72% had severe cognitive impairment. This study also found that moderate and severe cognitive impairment were both negatively associated with HRQoL. Older Australians with moderate cognitive impairment scored worse on the PCS (ß = - 1.765, SE = 0.317), MCS (ß = - 1.612, SE = 0.326), and SF-6D (ß = - 0.024, SE = 0.004) than peers without cognitive impairment given other covariates reference categories remain constant. Older adults experiencing severe cognitive had lower PCS (ß = - 3.560, SE = 1.103), and SF-6D (ß = - 0.034, SE = 0.012) scores compared to their counterparts with no cognitive impairment given other covariates reference categories remain constant. CONCLUSION: We found evidence that HRQoL is negatively associated with cognitive impairment. Our findings will be beneficial for the future cost-effectiveness intervention targeted at reducing cognitive impairment since it provides information on the disutility associated with moderate and severe cognitive impairment.

Mapping the schizophrenia quality of life scale to EQ-5D, HUI3 and SF-6D utility scores in patients with schizophrenia.

OBJECTIVES: The current study aimed to map the disease-specific Schizophrenia Quality of Life Scale (SQLS) onto the three- and five-level EuroQol five-dimension (EQ-5D-3 L and EQ-5D-5 L), Health Utility Index Mark 3 (HUI3) and Short Form six-dimensional (SF-6D) preference-based instruments to inform future cost-utility analyses for treatment of patients with schizophrenia. METHODS: Data from 251 outpatients with schizophrenia spectrum disorders was included for analysis. Ordinary least square (OLS), Tobit and beta regression mixture models were employed to estimate the utility scores. Three regression models with a total of 66 specifications were determined by goodness of fit and predictive indices. Distribution of the original data to the distributions of the data generated using the preferred estimated models were then compared. RESULTS: EQ-5D-3 L and EQ-5D-5 L were best predicted by the OLS model, including SQLS domain scores, domain-squared scores, age, and gender as explanatory predictors. The models produced the best performance index and resembled most closely with the observed EQ-5D data. HUI3 and SF-6D were best predicted by the OLS and Tobit model respectively. CONCLUSION: The current study developed mapping models for converting SQLS scores into generic utility scores, which can be used for economic evaluation among patients with schizophrenia.

Responsiveness and construct validity of EPIC-26, AQoL-6D and SF-6D following treatment in prostate cancer.

PURPOSE: To assess construct validity and responsiveness of the Expanded Prostate Cancer Index Composite Instrument (EPIC-26) relative to the Short-Form Six-Dimension (SF-6D) and Assessment of Quality of Life 6-Dimension (AQoL-6D) in patients following treatment for prostate cancer. METHODS: Retrospective prostate cancer registry data were used. The SF-6D, AQoL-6D, and EPIC-26 were collected at baseline and one year post treatment. Analyses were based on Spearman's correlation coefficient, Bland-Altman plots and intra-class correlation coefficient, Kruskal Wallis, and Effect Size and the Standardised Response Mean for responsiveness. RESULTS: The study sample was comprised of 1915 patients. Complete case analysis of 3,697 observations showed moderate evidence of convergent validity between EPIC-26 vitality/hormonal domain and AQoL-6D (r = 0.45 and 0.54) and SF-6D (r = 0.52 and 0.56) at both timepoints. Vitality/hormonal domain also showed moderate convergent validity with coping domain of AQoL-6D (r = 0.45 and 0.54) and with role (r = 0.41 and 0.49) and social function (r = 0.47 and 0.50) domains of SF-6D at both timepoints, and with independent living (r = 0.40) and mental health (r = 0.43) of AQoL-6D at one year. EPIC-26 sexual domain had moderate convergent validity with relationship domain (r = 0.42 and 0.41) of AQoL-6D at both timepoints. Both AQoL-6D and SF-6D did not discriminate between age groups and tumour stage at both timepoints but AQoL-6D discriminated between outcomes for different treatments at one year. All EPIC-26 domains discriminated between age groups and treatment at both timepoints. The EPIC-26 was more responsive than AQoL-6D and SF-6D between baseline and one year following treatment. CONCLUSIONS: AQoL-6D can be used in combination with EPIC-26 in place of SF-12. Although EPIC-26 is not utility based, its popularity amongst clinicians and ability to discriminate between disease-specific characteristics and post-treatment outcomes in clinical trials makes it a candidate for use within cost-effectiveness analyses. The generic measure provides a holistic assessment of quality of life and is suitable for generating quality adjusted life years (QALYs).

A systematic review of SF-6D health state valuation studies.

BACKGROUND: The short-form 6-dimension (SF-6D) is a preference-based measure designed to calculate quality-adjusted life-year (QALY). Preference-based measures are standardized multidimensional health state classifications with preference or utility weights elicited from a sample of the population. There is a concern that valuations may differ between countries because of differences in culture, thus invalidating the use of values obtained from one country to another. OBJECTIVE: To conduct a systematic review of elicitation methods and modeling strategies in SF-6D studies and to present a general comparison of dimensions' ordering among different countries. METHODS: We performed a systematic review of studies that developed value sets for the SF-6D. The data search was conducted in PubMed, ScienceDirect, Embase, and Scopus up to 8 September 2022. Quality of studies was assessed with the CREATE checklist. Methodological differences were identified, and the dimensions' ordering of the selected studies was analyzed by cultural and economic factors. RESULTS: From a total of 1369 entries, 31 articles were selected. This corresponded to 12 different countries and regions and 17 different surveys. Most studies used the standard gamble method to elicit health state preferences. Anglo-Saxon countries gave more importance to pain, while other countries have physical functioning as the highest dimension. As the economic level increases, people care less about physical functioning but more about pain and mental health. CONCLUSIONS: Value sets for the SF-6D are different from one country to another and there is a need to develop value sets for more countries to consider cultural and economic differences.