Health utility measurement for people living with HIV/AIDS under combined antiretroviral therapy: A comparison of EQ-5D-5L and SF-6D

We compared the discriminative validity, agreement and sensitivity of EQ-5D-5L and SF-6D utility scores in people living with HIV/AIDS (PLWHIV). We conducted a cross-sectional survey among PLWHIV aged more than 18 years old in 9 municipalities in Yunnan Province, China. A convenience sample was enrolled. We administered the SF-12 and EQ-5D-5L to measure health-related quality of life. The utility index of the SF-6D was derived from the SF-12. We calculate correlation coefficients to evaluate the relationship and agreement of 2 instruments. To evaluate the homogeneity of the EQ-5D-5L and SF-6D, intraclass correlation coefficients, scatter plots, and Bland-Altman plots were computed and drawn. We also used receiver operating characteristic curves to compare the discriminative properties and sensitivity of the econometric index. A total of 1797 respondents, with a mean age of 45.6 ± 11.7 years, was interviewed. The distribution of EQ-5D-5L scores skewed towards full health with a skewness of -3.316. The overall correlation between EQ-5D-5L and SF-6D index scores was 0.46 (P < .001). The association of the 2 scales appeared stronger at the upper end. An intraclass correlation coefficient of 0.59 between the EQ-5D-5L and SF-6D meant a moderate correlation and indicated general agreement. The Bland-Altman plot displayed the same results as the scatter plot. The receiver operating characteristic curve showed that the AUC for the SF-6D was 0.776 (95% CI: 0.757, 0.796) and that for the EQ-5D-5L was 0.732 (95% CI: 0.712, 0.752) by the PCS-12, and it was 0.782 (95% CI: 0.763, 0.802) for the SF-6D and 0.690 (95% CI: 0.669, 0.711) for the EQ-5D-5L by the MCS-12. Our study demonstrated evidence of the performance of EQ-5D-5L and SF-6D index scores to measure health utility in people living with HIV/AIDS. There were significant differences in their performance. We preferred to apply the SF-6D to measure the health utility of PLWHIV during the combined antiretroviral therapy period. Our study has demonstrated evidence for instrument choice and preference measurements in PLWHIV under combined antiretroviral therapy.

Association Between Cognition, Health Related Quality of Life, and Costs in a Population at Risk for Cognitive Decline

Background:

The association between health-related quality of life (HRQoL) and care costs in people at risk for cognitive decline is not well understood. Studying this association could reveal the potential benefits of increasing HRQoL and reducing care costs by improving cognition.

Objective:

In this exploratory data analysis we investigated the association between cognition, HRQoL utilities and costs in a well-functioning population at risk for cognitive decline.

Methods:

An exploratory data analysis was conducted using longitudinal 2-year data from the FINGER study (n = 1,120). A change score analysis was applied using HRQoL utilities and total medical care costs as outcome. HRQoL utilities were derived from the Short Form Health Survey-36 (SF-36). Total care costs comprised visits to a general practitioner, medical specialist, nurse, and days at hospital. Analyses were adjusted for activities of daily living (ADL) and depressive symptoms.

Results:

Although univariable analysis showed an association between cognition and HRQoL utilities, multivariable analysis showed no association between cognition, HRQoL utilities and total care costs. A one-unit increase in ADL limitations was associated with a -0.006 (p < 0.001) decrease in HRQoL utilities and a one-unit increase in depressive symptoms was associated with a -0.004 (p < 0.001) decrease in HRQoL utilities.

Conclusion:

The level of cognition in people at-risk for cognitive decline does not seem to be associated with HRQoL utilities. Future research should examine the level at which cognitive decline starts to affect HRQoL and care costs. Ideally, this would be done by means of cross-validation in populations with various stages of cognitive functioning and decline.

Comparison of the psychometric properties of the EQ-5D-3L and SF-6D in the general population of Chengdu city in China

The EQ-5D-3L and SF-6D are the most commonly used economic evaluation instruments. Data comparing the psychometric properties of the instruments are scarce in the Chinese population. This study compared the psychometric properties of these measures in the Chinese general population in Chengdu.From October to December 2012, 2186 respondents (age ≥18) were selected from urban and rural areas of Chengdu, China, via multistage stratified cluster sampling. Correlations, scatter plots and Bland-Altman plots were used to explore the relationships between the 2 measures. Ceiling and floor effects were used to analyze the score distribution. The known-groups method was used to evaluate discriminant validity.Among 2186 respondents, 2182 completed the questionnaire, and 2178 (18-82 years old, mean 46.09 ± 17.49) met the data quality requirement. The mean scores for the EQ-5D-3LCN, EQ-5D-3LUK, and SF-6DUK were 0.95 (Std: 0.11), 0.93 (Std: 0.15), and 0.79 (Std: 0.12), respectively. The correlations between domains ranged from 0.16 to 0.51. The correlation between the EQ-5D-3LCN and SF-6DUK and between the EQ-5D-3LUK and SF-6DUK was 0.46. The scatter plots and Bland-Altman plots demonstrated poor agreement between the EQ-5D-3L and SF-6D. The floor and ceiling effects were respectively 0.05% and 74.60% for the EQ-5D-3L and 0.05% and 2.53% for the SF-6DUK. The EQ-5D-3LCN, EQ-5D-3LUK and SF-6D have good discriminant validity in different sociodemographic and health condition groups. The SF-6D has higher level of discriminant validity in moderately healthy groups in the EQ-5D-3L full-health population.Both the EQ-5D-3L and SF-6D are valid economic evaluation instruments in the Chinese general population in Chengdu but do not seem to be interchangeable. The EQ-5D-3L has a higher ceiling effect and higher level of discriminant validity among different sociodemographic groups, and the SF-6D has a lower ceiling effect and higher level of discriminant validity in health condition groups. Users may consider the evidence in the choice of these instruments.

Impact of mapped EQ-5D utilities on cost-effectiveness analysis: in the case of dialysis treatments

Objectives

This study aimed to evaluate the performance of EQ-5D data mapped from SF-12 in terms of estimating cost effectiveness in cost-utility analysis (CUA). The comparability of SF-6D (derived from SF-12) was also assessed.

Methods

Incremental quality-adjusted life years (QALYs) and incremental cost-effectiveness ratios (ICERs) were calculated based on two Markov models assessing the cost effectiveness of haemodialysis (HD) and peritoneal dialysis (PD) using utility values based on EQ-5D-5L, EQ-5D using three direct-mapping algorithms and two response-mapping algorithms (mEQ-5D), and SF-6D. Bootstrap method was used to estimate the 95% confidence interval (percentile method) of incremental QALYs and ICERs with 1000 replications for the utilities.

Results

In both models, compared to the observed EQ-5D values, mEQ-5D values expressed much lower incremental QALYs (range − 14.9 to − 33.2%) and much higher ICERs (range 17.5 to 49.7%). SF-6D also estimated lower incremental QALYs (− 29.0 and − 14.9%) and higher ICERs (40.9 and 17.5%) than did the observed EQ-5D. The 95% confidence interval of incremental QALYs and ICERs confirmed the lower incremental QALYs and higher ICERs estimated using mEQ-5D and SF-6D.

Conclusion

Compared to observed EQ-5D, EQ-5D mapped from SF-12 and SF-6D would under-estimate the QALYs gained in cost-utility analysis and thus lead to higher ICERs. It would be more sensible to conduct CUA studies using directly collected EQ-5D data and to designate one single preference-based measure as reference case in a jurisdiction to achieve consistency in healthcare decision-making.

Electronic supplementary material

The online version of this article (10.1007/s10198-018-0987-x) contains supplementary material, which is available to authorized users.

Generic Preference-based Measures for Low Back Pain: Which of Them Should Be Used?

STUDY DESIGN

Systematic review.

OBJECTIVE

This systematic review examines validity and responsiveness of three generic preference-based measures in patients with low back pain (LBP).

SUMMARY OF BACKGROUND DATA

LBP is a very common incapacitating disease with a significant impact on health-related quality of life (HRQoL). Health state utility values can be derived from various preference-based HRQoL instruments, and among them the most widely ones are EuroQol 5 dimensions (EQ-5D), Short Form 6 Dimensions (SF-6D), and Health Utilities Index 3 (HUI III). The ability of these instruments to reflect HRQoL has been tested in various contexts, but never for LBP populations.

METHODS

A systematic search on electronic literature databases was undertaken to identify studies of patients with LBP where health state utility values were reported. Records were screened using a set of predefined eligibility criteria. Data on validity (correlations and known group methods) and responsiveness (effect sizes, standardized response means, tests of statistical significance) of instruments were extracted using a customized extraction template, and assessed using predefined criteria.

RESULTS

There were substantial variations in the 37 included papers identified in relation to study design and outcome measures used. EQ-5D demonstrated good convergent validity, as it was able to distinguish between known groups. EQ-5D was also able to capture changes of health states as results of different interventions. Evidence for SF-6D and HUI III was limited to allow an appropriate evaluation.

CONCLUSION

EQ-5D performs well in LBP population and its scores seem to be suitable for economic evaluation of LBP interventions. However, the paucity of information on the other instruments makes it impossible to determine its relative validity and responsiveness compared with them.

Validation and comparison of EuroQoL-5 dimension (EQ-5D) and Short Form-6 dimension (SF-6D) among stable angina patients

OBJECTIVES

Several preference-based health-related quality of life (HRQoL) instruments have been published and widely used in different populations. However no consensus has emerged regarding the most appropriate instrument in therapeutic area of stable angina. This study compared and validated the psychometric properties of two generic preference-based instruments, the EQ-5D and SF-6D, among Chinese stable angina patients.

METHODS

Convergent validity of the EQ-5D and SF-6D was examined with eight a priori hypotheses from stable angina patients in conjunction with Seattle Angina Questionnaire (SAQ). Responsiveness was compared using the effect size (ES), relative efficiency (RE) and receiver operating characteristic (ROC) curves. Agreement between the EQ-5D and SF-6D was tested using intra-class correlation coefficient (ICC) and Bland-Altman plot. Factors affecting utility difference were explored with multiple linear regression analysis.

RESULTS

In 411 patients (mean age 68.08 ± 11.35), mean utility scores (SD) were 0.78 (0.15) for the EQ-5D and 0.68 (0.12) for the SF-6D. Validity was demonstrated by the moderate to strong correlation coefficients (Range: 0.368-0.594, P< 0.001) for five of the eight hypotheses in both the EQ-5D and SF-6D. There were no serious floor effects for the EQ-5D and SF-6D, but ceiling effects for the EQ-5D were large. The areas under ROC of them all exceeded 0.5 (0.660-0.814, P< 0.001). The SF-6D showed a better discriminative capacity (ES: 0.573 to 1.179) between groups with different stable-angina-specific health status than the EQ-5D (ES: 0.426 to 1.126). RE suggested that the SF-6D (RE: 44.8 to 177.8%) was more efficient than the EQ-5D except for physical function. Poor agreement between them was observed with ICC (0.448, P< 0.001) and Bland-Altman plot analysis. Multiple liner regression showed that clinical variables significantly (P< 0.05) influenced differences in utility scores between the EQ-5D and SF-6D.

CONCLUSIONS

Both EQ-5D and SF-6D are valid and sensitive preference-based HRQoL instruments in Chinese stable angina patients. The SF-6D may be a more effective tool with lower ceiling effect and greater sensitivity. Further study is needed to compare other properties, such as reliability and longitudinal response.

Health-related quality of life for pre-diabetic states and type 2 diabetes mellitus: a cross-sectional study in Västerbotten Sweden

BACKGROUND

Type 2 diabetes (T2D) decreases health-related quality of life, but there is a lack of information about the health status of people in pre-diabetic states. However, information on health utility weights (HUWs) for pre-diabetic states and T2D are essential to estimate the effect of prevention initiatives. We estimated and compared HUWs for healthy individuals, those with pre-diabetes and those with T2D in a Swedish population and evaluated the influence of age, sex, education and body mass index on HUWs.

METHODS

Participants of the Västerbotten Intervention Program, Sweden, between 2002 and 2012, who underwent an oral glucose tolerance test or indicated they had T2D and who filled in the Short Form-36 questionnaire (SF-36) were included. Individuals were categorized as healthy, being in any of three different pre-diabetic states, or as T2D. The pre-diabetic states are impaired fasting glucose (IFG), impaired glucose tolerance (IGT) or a combination of both (IFG&IGT). The SF-6D index was used to convert SF-36 responses to HUWs. HUWs were stratified by age, sex, education and body mass index. Beta regression analyses were conducted to estimate the effect of multiple risk factors on the HUWs.

RESULTS

In total, 55 882 individuals were included in the analysis. The overall mean HUW was 0.764. The mean HUW of healthy individuals was 0.768, 0.759 for those with IFG, 0.746 for those with IGT, 0.745 for those with IFG&IGT, and 0.738 for those with T2D. In the overall model, all variables except underweight vs. normal weight were significantly associated with HUW. Younger age, male sex, and higher education were associated with increased HUW. Normal weight, or being overweight was associated with elevated HUW, while obesity was associated with lower HUW.

CONCLUSIONS

Healthy individuals had higher HUWs than participants with T2D, while individuals with IFG, IGT or IFG&IGT had HUWs that ranged between those for NGT and T2D. Therefore, preventing the development of pre-diabetic states would improve health-related quality of life in addition to lowering the risk of developing T2D.

The construct validity and responsiveness of the EQ-5D, SF-6D and Diabetes Health Profile-18 in type 2 diabetes

BACKGROUND

Interest in the measurement of health related quality of life and psychosocial functioning from the patient's perspective in diabetes mellitus has grown in recent years. The aim of this study is to investigate the psychometric performance of and agreement between the generic EQ-5D and SF-6D and diabetes specific DHP-18 in Type 2 diabetes. This will support the future use of the measures by providing further evidence regarding their psychometric properties and the conceptual overlap between the instruments. The results will inform whether the measures can be used with confidence alongside each other to provide a more holistic profile of people with Type 2 diabetes.

METHODS

A large longitudinal dataset (n = 1,184) of people with Type 2 diabetes was used for the analysis. Convergent validity was tested by examining correlations between the measures. Known group validity was tested across a range of clinical and diabetes severity indicators using ANOVA and effect size statistics. Agreement was examined using Bland-Altman plots. Responsiveness was tested by examining floor and ceiling effects and standardised response means.

RESULTS

Correlations between the measures indicates that there is overlap in the constructs assessed (with correlations between 0.1 and 0.7 reported), but there is some level of divergence between the generic and condition specific instruments. Known group validity was generally good but was not consistent across all indicators included (with effect sizes from 0 to 0.74 reported). The EQ-5D and SF-6D displayed a high level of agreement, but there was some disagreement between the generic measures and the DHP-18 dimensions across the severity range. Responsiveness was higher in those who self-reported change in health (SRMs between 0.06 and 0.25).

CONCLUSIONS

The psychometric assessment of the relationship between the EQ-5D, SF-6D and DHP-18 shows that all have a level of validity for use in Type 2 diabetes. This suggests that the measures can be used alongside each other to provide a more holistic assessment of with the quality of life impacts of Type 2 diabetes.

Gender differences in multiple underlying dimensions of health-related quality of life are associated with sociodemographic and socioeconomic status

PURPOSE

The purpose of the study was to examine whether gender differences in summary health-related quality of life (HRQoL) are due to differences in specific dimensions of health, and whether they are explained by sociodemographic and socioeconomic (SES) variation.

METHODS

The National Health Measurement Study collected cross-sectional data on a national sample of 3648 black and white noninstitutionalized adults ages 35 to 89 years. Data included the Short Form 36-Item survey, which yielded separate Mental and Physical Component Summary scores (MCS and PCS, respectively), and five HRQoL indexes: Short Form 6 dimension, EuroQol 5 dimension, the Health Utilities Indexes Mark 2 and 3, and the Quality of Well-Being Scale Self-Administered form. Structural equation models were used to explore gender differences in physical, psychosocial, and pain latent dimensions of the 5 indexes, adjusting for sociodemographic and SES indicators. Observed MCS and PCS scores were examined in regression models to judge robustness of latent results.

RESULTS

Men had better estimated physical and psychosocial health and less pain than women with similar trends on the MCS and PCS scores. Adjustments for marital status or income reduced gender differences more than did other indicators. Adjusting results for partial factorial invariance of HRQoL attributes supported the presence of gender differentials, but also indicated that these differences are impacted by dimensions being related to some HRQoL attributes differently by gender.

CONCLUSIONS

Men have better estimated health on 3 latent dimensions of HRQoL-physical, psychosocial, and pain-comparable to gender differences on the observed MCS and PCS scores. Gender differences are partly explained by sociodemographic and SES factors, highlighting the role of socioeconomic inequalities in perpetuating gender differences in health outcomes across multiple domains. These results also emphasize the importance of accounting for measurement invariance for meaningful comparison of group differences in estimated means of self-reported measures of health.

How valid and responsive are generic health status measures, such as EQ-5D and SF-36, in schizophrenia? A systematic review

OBJECTIVES

Generic health status measures such as the short form health survey (SF-36) and EuroQol-5D (EQ-5D) are increasingly being used to inform health policy. They are claimed to be applicable across disease areas and have started to be used within mental health research. This review aims to assess the construct validity and responsiveness of four generic health status measures in schizophrenia, including the preference-based SF-6D and EQ-5D.

METHOD

A systematic review of the literature was undertaken. Ten databases were searched from inception to August 2009 and reference lists scrutinized to identify relevant studies. Studies were appraised and data extracted. A narrative synthesis was performed of the evidence on construct validity including known groups validity (detecting a difference in health-related quality of life (HRQL) scores between two different groups such as samples from the general population and people with schizophrenia), convergent validity (strength of association between generic HRQL and other measures (e.g., symptom or functional), and responsiveness. Responsiveness was considered by: 1) differences in generic HRQL measure scores in responders/non-responders and 2) correlation between changes on generic HRQL measures and changes in specific measures obtained from patients and clinicians.

RESULTS

Thirty-three studies were identified that provided data on the validity and/or responsiveness of the instruments. Most of the evidence concerns the SF-36 and EQ-5D, and for these instruments there was evidence for known group validity. The evidence for convergent validity and responsiveness was mixed, with studies presenting contradictory results.

CONCLUSION

Although the evidence base is limited in a number of important respects, including problems with the measures used to develop constructs in the validation studies, it is sufficient to raise doubts about the use of generic measures of health like the EQ-5D and SF-36 in patients with schizophrenia.

Predicting SF-6D utility scores from the neck disability index and numeric rating scales for neck and arm pain

STUDY DESIGN

Cross-sectional cohort.

OBJECTIVE

This study aims to provide an algorithm to estimate Short Form-6D (SF-6D) utilities using data from the Neck Disability Index (NDI), neck pain, and arm pain scores.

SUMMARY OF BACKGROUND DATA

Although cost-utility analysis is increasingly used to provide information about the relative value of alternative interventions, health state values or utilities are rarely available from clinical trial data. The Neck Disability Index (NDI) and numerical rating scales for neck and arm pain are widely used disease-specific measures in patients with cervical degenerative disorders. The purpose of this study is to provide an algorithm to allow estimation of SF-6D utilities using data from the NDI, and numerical rating scales for neck and arm pain.

METHODS

SF-36, NDI, neck and arm pain rating scale scores were prospectively collected before surgery, at 12 and 24 months after surgery in 2080 patients undergoing cervical fusion for degenerative disorders. SF-6D utilities were computed, and Spearman correlation coefficients were calculated for paired observations from multiple time points between NDI, neck and arm pain scores, and SF-6D utility scores. SF-6D scores were estimated from the NDI, neck and arm pain scores were estimated using a linear regression model. Using a separate, independent dataset of 396 patients in which NDI scores were available, SF-6D was estimated for each subject and compared to their actual SF-6D.

RESULTS

The mean age for those in the development sample was 50.4 ± 11.0 years and 33% were male. In the validation sample, the mean age was 53.1 ± 9.9 years and 35% were male. Correlations between the SF-6D and the NDI, neck and arm pain scores were statistically significant (P < 0.0001) with correlation coefficients of 0.82, 0.62, and 0.50, respectively. The regression equation using NDI aloneto predict SF-6D had an R of 0.66 and a root mean square error of 0.056. In the validation analysis, there was no statistically significant difference (P 5 0.961) between actual mean SF-6D (0.49 6 0.08) and the estimated mean SF-6D score (0.49 6 0.08), using the NDI regression model.

CONCLUSION

This regression-based algorithm may be a useful tool to predict SF-6D scores in studies of cervical degenerative disease that have collected NDI but not utility scores.

Longitudinal association of preference-weighted health-related quality of life measures and substance use disorder outcomes

AIM

To examine the construct validity of generic preference-weighted health-related quality of life measures in a sample of patients with a substance use disorder (SUD).

DESIGN

Longitudinal (baseline and 6-month follow-up) data from a research study that evaluated interventions to improve linkage and engagement with SUD treatment.

SETTING

A central intake unit that referred patients to seven SUD treatment centers in a Midwestern US metropolitan area.

PARTICIPANTS

A total of 495 individuals with a SUD.

MEASUREMENTS

Participants completed two preference-weighted measures: the self-administered Quality of Well-Being scale (QWB-SA) and the standard gamble weighted Medical Outcomes Study SF-12 (SF-6D). They were also administered two clinical assessments: all seven domains of the Addiction Severity Index (ASI) and a symptom checklist based on the DSM-IV. Construct validity was determined via the relationships between disease-specific SUD and generic measures.

FINDINGS

In unadjusted analyses, the QWB-SA and SF-6D change scores were correlated significantly with six ASI subscale change scores, but not with employment status. In adjusted repeated-measures analyses, three of seven ASI subscale scores were significant predictors of QWB-SA and 5/7 ASI subscale scores were significant predictors of SF-6D. Abstinence and problematic use at follow-up were significant predictors of QWB-SA and SF-6D. Effect sizes ranged from 0.352 to 0.400 for abstinence and -0.484 to -0.585 for problematic use.

CONCLUSIONS

Generic preference-weighted health-related quality of life measures show moderate to good associations with substance-use specific measures and in certain circumstances can be used in their stead. This study provides further support for the use of the Quality of Well-Being scale and Medical Outcomes Study SF-12 in clinical and economic evaluations of substance use disorder interventions.

Gender differences in health-related quality-of-life are partly explained by sociodemographic and socioeconomic variation between adult men and women in the US: evidence from four US nationally representative data sets

PURPOSE

The purpose of this study was to describe gender differences in self-reported health-related quality-of-life (HRQoL) and to examine whether differences are explained by sociodemographic and socioeconomic status (SES) differentials between men and women.

METHODS

Data were from four US nationally representative surveys: US Valuation of the EuroQol EQ-5D Health States Survey (USVEQ), Medical Expenditure Panel Survey (MEPS), National Health Measurement Study (NHMS) and Joint Canada/US Survey of Health (JCUSH). Gender differences were estimated with and without adjustment for sociodemographic and SES indicators using regression within and across data sets with SF-6D, EQ-5D, HUI2, HUI3 and QWB-SA scores as outcomes.

RESULTS

Women have lower HRQoL scores than men on all indexes prior to adjustment. Adjusting for age, race, marital status, education and income reduced but did not remove the gender differences, except with HUI3. Adjusting for marital status or income had the largest impact on estimated gender differences.

CONCLUSIONS

There are clear gender differences in HRQoL in the United States. These differences are partly explained by sociodemographic and SES differentials.

Predicting SF-6D utility scores from the Oswestry disability index and numeric rating scales for back and leg pain

STUDY DESIGN

Cross-sectional cohort.

OBJECTIVE

The purpose of this study is to provide a model to allow estimation of utility from the Short Form (SF)-6D using data from the Oswestry Disability Index (ODI), Back Pain Numeric Rating Scale (BPNRS), and the Leg Pain Numeric Rating Scale (LPNRS).

SUMMARY OF BACKGROUND DATA

Cost-utility analysis provides important information about the relative value of interventions and requires a measure of utility not often available from clinical trial data. The ODI and numeric rating scales for back (BPNRS) and leg pain (LPNRS), are widely used disease-specific measures for health-related quality of life in patients with lumbar degenerative disorders. The purpose of this study is to provide a model to allow estimation of utility from the SF-6D using data from the ODI, BPNRS, and the LPNRS.

METHODS

SF-36, ODI, BPNRS, and LPNRS were prospectively collected before surgery, at 12 and 24 months after surgery in 2640 patients undergoing lumbar fusion for degenerative disorders. Spearman correlation coefficients for paired observations from multiple time points between ODI, BPNRS, and LPNRS, and SF-6D utility scores were determined. Regression modeling was done to compute the SF-6D score from the ODI, BPNRS, and LPNRS. Using a separate, independent dataset of 2174 patients in which actual SF-6D and ODI scores were available, the SF-6D was estimated for each subject and compared to their actual SF-6D.

RESULTS

In the development sample, the mean age was 52.5 +/- 15 years and 34% were male. In the validation sample, the mean age was 52.9 +/- 14.2 years and 44% were male. Correlations between the SF-6D and the ODI, BPNRS, and LPNRS were statistically significant (P < 0.0001) with correlation coefficients of 0.82, 0.78, and 0.72, respectively. The regression equation using ODI, BPNRS,and LPNRS to predict SF-6D had an R of 0.69 and a root mean square error of 0.076. The model using ODI alone had an R of 0.67 and a root mean square error of 0.078. The correlation coefficient between the observed and estimated SF-6D score was 0.80. In the validation analysis, there was no statistically significant difference (P = 0.11) between actual mean SF-6D (0.55 +/- 0.12) and the estimated mean SF-6D score (0.55 +/- 0.10) using the ODI regression model.

CONCLUSION

This regression-based algorithm may be used to predict SF-6D scores in studies of lumbar degenerative disease that have collected ODI but not utility scores.

Predicting an SF-6D preference-based score using MCS and PCS scores from the SF-12 or SF-36

BACKGROUND

The SF-6D preference-based scoring system was developed several years after the SF-12 and SF-36 instruments. A method to predict SF-6D scores from information in previous reports would facilitate backwards comparisons and the use of these reports in cost-effectiveness analyses.

METHODS

This report uses data from the 2001-2003 Medical Expenditures Panel Survey (MEPS), the Beaver Dam Health Outcomes Survey, and the National Health Measurement Study. SF-6D scores were modeled using age, sex, mental component summary (MCS) score, and physical component summary (PCS) score from the 2002 MEPS. The resulting SF-6D prediction equation was tested with the other datasets for groups of different sizes and groups stratified by age, MCS score, PCS score, sum of MCS and PCS scores, and SF-6D score.

RESULTS

The equation can be used to predict an average SF-6D score using average age, proportion female, average MCS score, and average PCS score. Mean differences between actual and predicted average SF-6D scores in out-of-sample tests was -0.001 (SF-12 version 1), -0.013 (SF-12 version 2), -0.007 (SF-36 version 1), and -0.010 (SF-36 version 2). Ninety-five percent credible intervals around these point estimates range from +/-0.045 for groups with 10 subjects to +/-0.008 for groups with more than 300 subjects. These results were consistent for a wide range of ages, MCS scores, PCS scores, sum of MCS and PCS scores, and SF-6D scores. SF-6D scores from the SF-36 and SF-12 from the same data set were found to be substantially different.

CONCLUSIONS

Simple equation predicts an average SF-6D preference-based score from widely published information.