EQ-5D-3L and EQ-5D-5L population norms for Thailand

BACKGROUND

The previous Thai norm-based scores for the EQ-5D-5L were established with Thai general population samples aged 20-70 years in 2019. Nevertheless, these values need to be updated after the COVID-19 pandemic because of its effects on both physical and mental health. This study therefore aimed to establish population norms of the Thai EQ-5D-3L, EQ-5D-5L and EQ-VAS scores as well as to estimate disutility values associated with self-reported main diseases.

METHODS

Individual face-to-face interviews were conducted with 2000 adult (age ≥ 18 years) members of the general Thai population to estimate norm-based scores. Each participant completed the EQ-5D-3L and EQ-5D-5L as well as questions related to their sociodemographic factors and self-reported main diseases. Responses to the two instruments were converted to health utility (HU) scores on the basis of available value sets. Descriptive statistics were used to report the norm-based scores stratified by age and sex categories. Response redistribution determining the response consistency between EQ-5D versions was investigated. The HU score agreement from those two instruments was investigated using intraclass correlation coefficient (ICC). Tobit regression models were employed to investigate the relationships between sociodemographic factors and HU and EQ-VAS scores. Moreover, it was used to estimate the disutility values associated with self-reported main diseases.

RESULTS

The means (percentage of ceiling effects) of EQ-5D-3L, EQ-5D-5L, and EQ-VAS scores were 0.845 (57.80%), 0.923 (49.05%), and 79.83 (3.20%), respectively. The average percentage of inconsistent response was 1.09%. A good agreement level was found between both EQ-5D versions with the ICCs of 0.789 (95% CI: 0.558-0.878). Female, older, and unemployed participants and those with BMI ≥ 30 reported lower EQ-5D-3L and EQ-5D-5L than their counterparts. Bone/Joint disorder and stroke contributed to the largest disutility value for those two instruments.

CONCLUSIONS

The Thai norm-based scores from those two instruments were diminished when advancing age and among female, unemployed, and obese (BMI ≥ 30) participants. It is expected to provide information to policy makers to better allocate health care resources to those with diminished norm-based scores.

Psychometric evaluation of the WHOQOL-BREF and its shorter versions for general Thai population: confirmatory factor analysis and Rasch analysis

PURPOSE

Rasch analysis was employed to validate the World Health Organization Quality of Life-BREF (WHOQOL-BREF) and its existing shorter versions in the general Thai population.

METHODS

1200 respondents were randomly selected to complete the questionnaire. Confirmatory factor analysis (CFA) was employed to test the structure of the WHOQOL-BREF and its shorter versions with the random sub-sample of 900 respondents, while Rasch analysis was performed with a random sub-sample of 300 respondents.

RESULTS

The CFA confirmed the factor structure of WHOQOL-BREF and its shorter versions. The Rasch analysis revealed that the WHOQOL-BREF, when a four-domain structure was tested using a subtest approach, achieved acceptable model fit to the Rasch model and met the expectations of unidimensionality with high reliability (PSI = 0.87). Individual domain models were also unidimensional, but reliability of the 3-item social domain was inadequate. While the 8-item EUROHIS-QOL-8 and 5-item WHOQOL-5 achieved an overall acceptable fit and met the expectations of unidimensionality, the reliability of the WHOQOL-5 was below the acceptable threshold (PSI = 0.66). Reliability of the EUROHIS-QOL-8 was satisfactory (PSI = 0.79).

CONCLUSIONS

The WHOQOL-BREF is a valid instrument for use in the Thai general population, both as a total score as well as individual subscales. Rasch analysis also supports the use of EUROHIS-QOL-8, but the WHOQOL-5 lacks good reliability. While the reliability of the EUROHIS-QOL-8 is sufficiently high for between-group analysis, the Thai WHOQOL-BREF total score can also be used for within-participant analyses. Rasch investigation with a more varied health conditions of general Thai samples or patient groups is encouraged for future studies.

Health-related quality of life and willingness to pay measurement among patients on warfarin in Thailand

BACKGROUND

Complex dosage regimens and the high incidence of adverse events associated with warfarin therapy can affect the health-related quality of life (HRQoL) and willingness to pay (WTP) among patients on warfarin. No such previous study has been conducted to assess the HRQoL and WTP among Thai patients on warfarin; therefore, this study aimed to measure these parameters and identify some sociodemographic factors associated with those aspects among patients on warfarin in Thailand.

METHODS

This cross-sectional survey study involving 260 patients on warfarin between June 2022 and June 2023 used a quantitative method for data collection. Face-to-face interviews with well-trained interviewers were conducted and patients were required to complete the questionnaires of both World Health Organization Quality of Life-BREF (WHOQOL-BREF) and EQ-5D-5L to assess and measure their HRQoL levels. WTP was assessed using a bidding game technique. Descriptive statistics with mean and standard deviations were used to report HRQoL scores and WTP, whereas a generalized linear model was employed to identify factors associated with both HRQoL and WTP.

RESULTS

The mean EQ-5D index and mean EQ-VAS score were 0.89 ± 0.15 and 76.92 ± 15.95, respectively, whereas the mean WHOQOL-BREF domain scores were 59.18 ± 14.13, 68.56 ± 15.47, 59.13 ± 19.64, and 65.23 ± 14.04 for the physical, psychological, social, and environmental domains, respectively. Elderly participants (age > 60 years) and those with comorbidities had lower HRQoL scores than their counterparts. The mean WTP was 22.25 ± 32.19 USD for one patient's visit. The presence of comorbidities was the only factor significantly associated with WTP values.

CONCLUSIONS

Thai patients on warfarin have lower mean EQ-5D indexes and EQ-VAS scores than members of the general Thai population. Patients on warfarin with comorbidities have diminished HRQoL and WTP values. Therefore, all healthcare professionals should pay more attention to this group of patients on warfarin to achieve better outcomes.

After morning, phew! A knowledge, attitudes, and practices survey related to emergency oral contraception in Thai pharmacists

INTRODUCTION

Pharmacists' knowledge and attitude toward Emergency Oral Contraception (EOC) can affect users' access to EOCs, especially where EOCs are provided by pharmacists without the need for prescriptions. We conducted a Knowledge, Attitudes, and Practice (KAP) survey on Thai pharmacists to better understand KAP related to EOCs and the correlation among KAP components.

METHODS

An in-depth interview, GoogleTrend search, and Pantip.com search were conducted. The findings, together with data from a previously published systematic review and meta-analysis, were used to develop KAP survey questions which were distributed online. Spearman's rank correlation coefficient and linear mixed model were used to investigate the correlation and association among KAP components.

RESULTS

The in-depth interview with pharmacists showed that sex and unwanted pregnancy are very sensitive topics in Thailand. Sex and EOC education should be provided by parents and healthcare professionals at a young age. This agreed with opinions from Thai internet users that sex literacy was generally low and sex education was not provided adequately. From the total of 421 survey responses, Thai pharmacists had average knowledge, poor attitude, and average practice related to EOCs (median score = 51.02%, 21.81%, and 60.0%, respectively). The correlations between KAP in pharmacists were weak (ρ = 0.107-0.525, p < 0.02). Pharmacists who rated themselves as having higher scores in knowledge and attitude also rated themselves higher in the practice score. However, the total scores describing the knowledge of or attitude toward EOCs were not associated with EOC practice scores.

CONCLUSIONS

In Thai pharmacists, self-rating KAP scores overestimated total KAP scores. The correlation among KAP components was weak. EOC knowledge and attitudes should be promoted, although this may not improve EOC practice in Thai pharmacists.

Normative profile of the EQ-5D-5L dimensions, EQ-5D-5L index and EQ-VAS scores for the general Thai population

PURPOSE

To generate a normative profile for the EQ-5D-5L dimensions, EQ-5D-5L index, and EQ-VAS scores of the general Thai population and to examine the associations between sociodemographic characteristics and their norm-based scores.

METHODS

Data from 2019 general Thai samples were employed to estimate the norm-based scores elicited using the Thai EQ-5D-5L value set. Descriptive statistics were used to estimate the norm-based scores stratified by gender and six age bands to obtain the normative profile for the general Thai population. Multivariable logistic and Tobit regression models were used to investigate the relationships between sociodemographic characteristics and EQ-5D-5L dimensions, EQ-5D-5L index, and EQ-VAS scores.

RESULTS

The mean EQ-5D-5L index and EQ-VAS scores were 0.931 and 82.3, respectively. Approximately 88.9% of the participants reported 19 out of 3125 (3%) possible health states. The odds of having problems with mobility was greatest for the sample aged ≥ 65 years and declined with decreasing age. Women, samples with advancing age, and those with a household income of ≤ 10,000 Baht/month and fair and poor health perceptions were more likely to report a lower EQ-5D-5L index. Furthermore, advanced age and fair and poor health perception were significantly associated with lower EQ-VAS scores.

CONCLUSION

The EQ-5D-5L population norms were established as the benchmark for both EQ-5D-5L index and EQ-VAS scores for the general Thai population. This is expected to support the health service research and inform policymakers on the allocation of limited healthcare resources.

Mapping of the World Health Organization Quality of Life Brief (WHOQOL-BREF) to the EQ-5D-5L in the General Thai Population

PURPOSE

This study aimed at mapping the World Health Organization Quality of Life Brief (WHOQOL-BREF) and the EQ-5D-5L in the general Thai population and to determine the impact on the incremental cost-utility ratio (ICUR) through five hypothetical scenarios.

METHODS

A total of 1,200 Thai participants were randomly allocated into the 'estimation' and 'validation' groups. A curve estimation with nine regression models was performed to identify the best-fit regression model of significant WHOQOL-BREF dimension scores for the EQ-5D-5L index score predictions in the estimation group. The identified model was then used for the calculation of the predicted EQ-5D-5L index scores in the validation group. The percentage change from the hypothetical base-case scenario with predefined parameters was used to determine the impact on the ICUR.

RESULTS

An inverse model was the best-fit regression model to predict the EQ-5D-5L index scores. The absolute difference between the predicted and observed index scores was 0.064, and the percentage of the sample that was mispredicted by ≥ 0.05 and ≥ 0.1 was 43.8% and 16.8%, respectively. Moreover, the percentage change in ICUR ranged between 0.13 and 1.84% from the hypothetical base-case scenario.

CONCLUSIONS

An inverse relationship between the studied scores was identified. The minimal impact on the ICUR suggests that the Health Utility Index of the mapped equation can be applied to economic analyses.

A comparison of measurement properties between UK SF-6D and English EQ-5D-5L and Thai EQ-5D-5L value sets in general Thai population

BACKGROUND

Evidence is limited for comparative psychometric properties between EQ-5D-5L and SF-6D. Therefore, this study compared psychometric properties between those instruments using value sets from Thailand, England, and the UK in the general Thai population.

METHODS

A total of 1,200 participants were recruited. The agreement level was evaluated using intraclass correlation coefficients (ICCs) and Bland-Altman plots. Convergent validity with SF-12v2 was assessed by Spearman's rho correlations. Known-group validity compared discriminant activity and sensitivity between groups. Responsiveness was assessed using standardized effect sizes (SES) and standardized response mean (SRM).

RESULTS

Agreement between SF-6D and Thai (ICCs = 0.51) and English (ICCs = 0.52) EQ-5D-5L index scores was good. The physical functioning demonstrated moderate to strong and moderate correlations with Thai (r = 0.50) and English (r = 0.46) EQ-5D-5L index scores, whereas SF-6D index scores strongly correlated with role emotion (r = 0.81). EQ-5D-5L was better than SF-6D at discrimination and sensitivity for gender, age, education level, household income, and number of diseases. The SF-6D was more responsive than the EQ-5D-5L for the worsened group.

CONCLUSION

Both SF-6D and EQ-5D-5L are valid among the general Thai population. Further studies should reinvestigate responsiveness and determine their impacts on economic analyses among patient groups.

Psychometric properties comparison between EQ-5D-5L and EQ-5D-3L in the general Thai population

PURPOSE

Evidence for the EQ-5D-5L's psychometric properties in the general Thai population is limited. This study aimed to compare ceiling effect, discriminatory power, response redistribution, validity, reliability between the EQ-5D-5L (5L) and the EQ-5D-3L (3L) in the general Thai population.

METHODS

1200 participants were randomly selected. The Shannon index ([Formula: see text] and Shannon evenness index ([Formula: see text] determining discriminatory power of both EQ-5D versions in each dimension were compared. Test-retest reliability was evaluated using weighted kappa (k) and intraclass correlation coefficients (ICCs). Validity was evaluated by correlations between similar dimensions of the EQ-5D, WHOQOL-BREF, and SF-12v2 and known-groups validity. The ceiling effects for the 3L and for the 5L were compared.

RESULTS

The 5L had lower ceiling effects than the 3L (49.08% vs 57.17%, p < 0.01). [Formula: see text] was higher for the 5L than for the 3L, but [Formula: see text] showed otherwise. Moderate correlations were detected between similar dimensions of the EQ-5D and the WHOQOL-BREF and SF-12v2. ICCs and k of the 3L were slightly higher than those of the 5L (ICCs: 0.78 vs 0.71) and (k: 0.42-0.63 vs 0.48-0.61), respectively. Older, female participants and those with comorbidities reported a lower utility index for both versions.

CONCLUSION

Evidence supported use of both EQ-5D versions in the general Thai population. The 5L had better ceiling effects and discriminant activity, while it showed comparable known-groups validity with the 3L. Nevertheless, evidence is limited for the superiority of reliability between these two versions, so more future research is required to investigate it.

A systematic review of the development and testing of additional dimensions for the EQ-5D descriptive system

Introduction: As the five dimensions of the EQ-5D might be insensitive to some populations or conditions, adding one or more specific 'bolt-on dimensions', to the EQ-5D may improve its validity and relevance for those groups. Various bolt-on dimensions have been identified and tested the effect on the psychometric performance and utility measurement. Therefore, this systematic review was to review all bolt-on dimensions and report the results of those two effects. Areas covered: Twelve studies were identified through PubMed, Scopus, and Web of Sciences from inception to January 2019. The bolt-on dimensions generally improved the EQ-5D's psychometric performance when compared with the standard version. However, evidence is lacking about the impact of bolt-on dimensions on responsiveness, reliability and known-groups validity. Evidence was also mixed for adding a sleep dimension, while interpersonal relationships did not promote a significant improvement on utility measurement. Expert opinion: Adding bolt-on dimensions could enhance the discriminative power and utility measurement of the EQ-5D; however, careful investigation of the sleep and interpersonal relationships is required since the evidence did not support a significant improvement. Further investigation of the identified bolt-on dimensions on all of the psychometric performance and the incremental utility scores derived from TTO is greatly encouraged.

Adding two culture-specific 'bolt-on' dimensions on the Thai version of EQ-5D-5L: an exploratory study in patients with diabetes

BACKGROUND

This study explored whether addition of culture-specific bolt-on dimensions, 'interpersonal relationships (IR)' and 'activities related to bending knees (AK)' improves the relevance and validity of the EQ-5D among Thai patients with diabetes.

METHODS

A cross-sectional study was conducted among 200 diabetic patients. Ceiling/floor effects, known-groups validity and test-retest reliability were evaluated. Hierarchical multiple regressions was performed to evaluate the incremental value of the EQ-5D+AK+IR over the EQ-5D-5L in predicting utility measured by visual analog scale (VAS).

RESULTS

The EQ-5D+AK+IR reduced ceiling effects by 34%. For known-groups validity, women and lower educated patients reported more AK problems (p-value< 0.05); however, none of the IR dimension hypotheses were supported. Both IR and AK had the weighted kappa coefficients of 0.49, indicating good reliability. Hierarchical multiple regression found that adding AK (adjusted r²: 0.182 vs 0.156), but not IR (adjusted r²: 0.157 vs 0.156) significantly increased the explained variance in VAS score.

CONCLUSION

Preliminary findings suggest that AK, but not IR, may be a useful addition to the EQ-5D questionnaire for use with Thai patients. Further studies in diverse populations are needed to examine the impacts of the proposed new dimensions and determine if these cultural adaptations are justified.

Psychometric testing of the health-related quality of life measurement, SF-36v2, in the general population of Thailand

BACKGROUND

The SF-36v2 is commonly used instrument worldwide. Nevertheless, it lacks the evidence of psychometric testing and health-related quality of life (HRQoL) level among the general Thai population. Therefore, this study aimed to investigate the psychometric performance and to evaluate the HRQoL level and the factors associated with it in the general Thai population.

METHODS

Cross-sectional research was conducted with 600 Thai subjects. Various psychometric properties were investigated including ceiling/floor effects, item-scale and scale levels validity using correlations, principal component analysis (PCA), and internal consistency. Multiple regression was used to assess the impact of demographic factors on the HRQoL level.

RESULTS

Cronbach's alpha ranged from 0.703 to 0.858. These eight SF-36v2 scales had a high ceiling effect while no floor effects were observed except for Bodily pain and General health. Correlations between the eight scales and two summary components, and item-scale correlations supported the hypotheses. Physical and Mental Health components were identified by PCA. Multiple regression revealed that having chronic diseases diminished HRQoL level.

CONCLUSIONS

These preliminary results confirmed that the Thai SF-36v2 was a valid and reliable instrument. Having chronic diseases diminished the HRQoL level. Further study investigating subjects in different severity and impact of other factors on HRQoL level is encouraged.