A Study of the Construct Validity of the Health Utilities Index Mark 3 (HUI3) in Patients with Schizophrenia

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.

5-Year Observation Period of Quality of Life After Cochlear Implantation

BACKGROUND

Only few studies assessed health-related quality of life (HRQoL) in cochlear implant (CI) patients for a period of more than 2 years. Some of these studies indicated that HRQoL might decrease after that period. The goal of our study was to see whether HRQoL indeed decreases or remains stable beyond 2 years after implant activation.

METHODS

Twenty-five adults (11 women, 14 men; mean age at implantation: 60 ± 19 yr) with a unilateral CI for profound hearing loss were administered two questionnaires: the Nimjegen Cochlear Implant Questionnaire and the Health Utility Index 3 (HUI 3). The Nimjegen Cochlear Implant Questionnaire total score and the HUI single-attribute utility score of Hearing are measures of hearing-specific HRQoL, whereas the HUI multiattribute utility score is a measure of generic HRQoL. The questionnaires were administered before cochlear implantation and 1, 2, and 5 years after implant activation.

RESULTS

Hearing-specific HRQoL was significantly improved at 1 year after implant activation and did not significantly change thereafter. Generic HRQoL also showed significant improvement at 1 year after implant activation, but deteriorated to a clinically relevant degree thereafter.

CONCLUSIONS

The significant improvement of hearing-specific HRQoL obtained from cochlear implantation was fully maintained for up to 5 years after implantation. Generic HRQoL of our CI patients, however, fluctuated over time. The decrease of generic HRQoL is supposed to reflect general age-associated health declines.

Mapping the PHQ-8 to EQ-5D, HUI3 and SF6D in patients with depression

BACKGROUND

There is limited evidence of mapping clinical instruments to a generic preference-based instrument in Asian patient populations. The current study aims to map the eight-item Patient Health Questionnaire depression scale (PHQ-8) onto the EuroQol Five-Dimension (EQ-5D), the Health Utilities Index Mark 3 (HUI3) and the Short Form Six-Dimension (SF-6D) which helps to inform future cost-utility analyses of treatments for depression.

METHODS

A total of 249 participants who had completed PHQ-8, EQ-5D, SF-6D and HUI3 questionnaires were included in the analyses. A beta regression mixture model was used to map the utility scores as a function of PHQ-8 total scores, PHQ-squared, age and gender. The predictive accuracy of the models was examined using mean absolute error and root mean square error.

RESULTS

The results were compared against two common regression methods including Ordinary Least Square (OLS) and Tobit regression models. The mean age of the sample was 36.2 years (SD = 11.1). The mean EQ-5D-3L, EQ-5D-5L, HUI3 and SF-6D utility scores were 0.615, 0.709, 0.461 and 0.607, respectively. The EQ-5D-3L, EQ-5D-5L and SF-6D utility scores were best predicted by the beta mixture regression model consisting of PHQ-8 total sores, PHQ-squared, and covariates including age and gender. The HUI3 was best predicted by the OLS regression model.

CONCLUSIONS

The current study provides important evidence to clinicians and researchers about the mapping algorithms that can be used in economic evaluation among patients with depression.

Health State Utility Values in Schizophrenia: A Systematic Review and Meta-Analysis

OBJECTIVES

Patient preferences are increasingly important in informing clinical and policy decisions. Health-state utility values (HSUVs) are quantitative measures of people's preferences over different health states. In schizophrenia, there is no clarity about HSUVs across the symptoms' severity spectrum. This meta-analysis aims to synthesize the literature on HSUVs in people with schizophrenia.

METHODS

We searched Medline, PsycInfo, Embase, EconLit, The Cochrane Library, and specialized databases. The studies reporting HSUVs in people with schizophrenia were selected and pooled in a random-effects meta-analysis. The primary outcome was the mean HSUV obtained from participants.

RESULTS

A total of 54 studies involving 87 335 participants were included. The pooled estimate using direct elicitation was a mean HSUV of 0.79 (95% CI: 0.70-0.88) for mild symptomatic states, 0.69 (95% CI: 0.54-0.85) in moderate states, and 0.34 (95% CI: 0.13-0.56) in severe states. Studies using indirect techniques resulted in a pooled mean HSUV of 0.73 (95% CI: 0.67-0.78) applying the EuroQol 5-dimension, 0.66 (95% CI: 0.62-0.71) in the Short-Form 6-dimension, and 0.59 (95% CI: 0.57-0.61) using the Quality of Well-Being scale. All the estimates resulted in considerable heterogeneity, partially reduced by meta-regression.

CONCLUSION

Our findings suggest that the severity of psychotic symptoms has an important effect on HSUVs in schizophrenia, with values mirroring patients with disabling physical conditions such as cancer and stroke. Decision makers should be aware of these results when including people's preferences in trials, models, and policy decisions.

Measurement Properties of Commonly Used Generic Preference-Based Measures in East and South-East Asia: A Systematic Review

OBJECTIVES

Our aim was to systematically review published evidence on the construct validity, test-retest reliability and responsiveness of generic preference-based measures (PBMs) used in East and South-East Asia.

METHODS

This systematic review was guided by the COSMIN guideline. A literature search on the MEDLINE, EMBASE, PsycINFO and PubMed databases up to August 2019 was conducted for measurement properties validation papers of the EuroQol-5 Dimensions (EQ-5D), Short Form-6 Dimensions (SF-6D), Health Utilities Index (HUI), Quality of Well-Being (QWB), 15-Dimensional (15D) and Assessment of Quality of Life (AQOL) in East and South-East Asian countries. Included papers were disaggregated into individual studies whose results and quality of design were rated separately. The population-specific measurement properties (construct validity, test-retest reliability and responsiveness) of each PBM were assessed separately using relevant studies. The overall methodological quality of the studies used in each of the assessments was also rated.

RESULTS

A total of 79 papers containing 1504 studies were included in this systematic review. The methodological quality was 'very good' or 'adequate' for the majority of the construct validity studies (99%) and responsiveness studies (61%), but for only a small portion of the test-retest reliability studies (23%). EQ-5D was most widely assessed and was found to have 'sufficient' construct validity and responsiveness in many populations, while the SF-6D and EuroQol-Visual Analog Scale (EQ-VAS) exhibited 'inconsistent' construct validity in some populations. Scarce evidence was available on HUI and QWB, but current evidence supported the use of HUI.

CONCLUSIONS

This systematic review provides a summary of the quality of existing generic PBMs in Asian populations. The current evidence supports the use of EQ-5D as the preferred choice when a generic PBM is needed, and continuous testing of all PBMs in the region.

A comparison of the reliability and validity of SF-6D, EQ-5D and HUI3 utility measures in patients with schizophrenia and patients with depression in Singapore

There is limited evidence of a direct comparison of the psychometric performance of generic preference-based measures in patients with mental illness in an Asian patient population. The current study aimed to compare the test-retest reliability, convergent and known-group validity and magnitude of change in scores of the EuroQol Five-Dimension, Health Utility Index Mark 3 (HUI3) and Short-Form Six-Dimension (SF-6D) measures in patients with depression and patients with schizophrenia spectrum disorder. 500 patients were recruited from a tertiary psychiatric institution in Singapore. The Schizophrenia Quality of Life Scale (SQLS), 8-item Patient Health Questionnaire, Quality of Life Enjoyment and Satisfaction Questionnaire (Q-LES-Q), and Positive and Negative Syndrome Scale were also included. In the schizophrenia sample, the SF-6D was found to have higher test-retest validity, convergent validity with SQLS domain scores, known-group validity and magnitude of change in scores over 6-month follow up than other measures. In the depression sample, the HUI3 was found to have higher test-retest reliability, convergent validity with Q-LES-Q, known group validity and magnitude of change in scores than other measures. Results suggest that the SF-6D and HUI3 to be more suitable as a utility measure for patients with schizophrenia and depression in an Asian patient population.

Comparing disease-specific and generic quality of life measures in patients with schizophrenia

The current study aimed to compare the use of a disease-specific and a generic quality of life (QOL) measure in a group 251 outpatients with a schizophrenia spectrum disorder by examining their relationships with symptoms of schizophrenia, psychiatric and medical comorbidities, and other factors, as well as to determine which of these factors will be associated with the measurement discrepancy between the two measures. QOL was assessed with the generic Healthy Utility Index Mark 3 (HUI3) and disease-specific Schizophrenia Quality of Life Scale (SQLS), and symptom severity was determined using the Positive and Negative Syndrome Scale (PANSS). Symptom severity predicted both SQLS and HUI3, while psychiatric comorbidity predicted only the HUI3. Ethnicity, employment and PANSS depression factor were significantly associated with the measurement discrepancy. Using domain scores of the two QOL measures, the HUI3 appears to be superior in discriminating PANSS cognitive factor scores and medical comorbidity status compared to SQLS. Although the use of disease-specific QOL is generally preferred to track treatment progress in clinical settings, the two types of instruments measure non-overlapping aspects of QOL and the generic scales may better reflect QOL impairment due to overall clinical presentation.

The prevalence and moderators of clinical pain in people with schizophrenia: a systematic review and large scale meta-analysis

BACKGROUND

People with schizophrenia frequently have physical comorbidities that can cause pain. Experimental studies report reduced pain sensitivity among schizophrenia patients, but it remains unclear if clinically relevant pain is less prevalent in schizophrenia.

METHOD

We systematically searched major electronic databases from inception till 03/2014. Articles were included that reported the prevalence of clinical pain in people with schizophrenia. Two independent authors conducted searches, completed methodological quality assessment and extracted data. A random effects relative risks (RR) meta-analysis was conducted to determine the prevalence of all-cause and specific pain in schizophrenia, and the relative prevalence compared to the general population, and to assess moderators.

RESULTS

Altogether, 14 studies were included encompassing 242,703 individuals with schizophrenia (30.2-55.8 years) and 4,259,221 controls. Different types of pain were considered. The overall pooled prevalence of clinical pain in people with schizophrenia was 34.7% (95% CI=23.6-46.6). In the comparative analysis involving 7 studies with controls, the RR was 0.99 (95% CI=0.83-1.19). The pooled prevalence of headache among 94,043 individuals with schizophrenia was 29.9% (95% CI=3-69%) and the RR compared to 4,248,284 controls was 1.32 (95% CI=0.85-2.07). In moderator analyses, neither age, sex, study quality or pain assessment method influenced pain prevalence.

CONCLUSION

Clinical pain affects a third of people with schizophrenia and levels are similar with age- and sex-comparable controls. Future research is needed to determine if similar clinical pain prevalences in schizophrenia occur despite having more painful conditions, resulting from under-reporting, higher pain thresholds or lower help seeking behaviours.

Measuring quality of life in patients with schizophrenia: an update

In 1997, we published a review in PharmacoEconomics about quality of life (QOL) measurement in patients with schizophrenia. The objective of this article is to provide an update, as well as to revisit the development of the construct of QOL and its measurement as applied to schizophrenia. Since our previous article, there has been significant growth in the number of publications about QOL in schizophrenia. Unfortunately, alongside this significant increase in research interest, a number of concerns have also risen about the limitations and lack of impact the concept of QOL has on clinical care and health-policy decision making. A number of concerns previously outlined (such as lack of consensus on a uniform definition of QOL) continue to be an issue. However, we believe that a uniform definition may not be possible, and instead, it may be preferable to have several definitions, which may enrich the concept and broaden its usefulness. Some of the scales we reviewed in 1997 continue to be in use, while others are now rarely or never used. New scales with better psychometrics have been introduced, but most are without theoretical or conceptual foundation. On the other hand, the field of scaling in general has been changing over the past few years and is moving towards a new approach for scale development, based on item response theory, item banks and computer adaptive testing. Unfortunately, this has not extended to QOL in schizophrenia. There continues to be a dearth of theoretical and conceptual models for QOL in schizophrenia, which seems to create the perception that the construct lacks a good theoretical and scientific foundation. One of the major gaps identified in this review is the recognized lack of impact of QOL measurements on clinical management or policy decision making. The majority of publications continue to focus on measurement rather than what to do with the data. The lack of strategies to integrate QOL data in clinical care, as well as the failure to contribute to policy decisions, particularly in cost analysis or resource allocations, has created the perception that the construct of QOL in schizophrenia is not that useful. It is evident that, for QOL in schizophrenia to regain its promise, researchers must take the ultimate next step beyond measurement: to develop credible strategies for integrating QOL data in clinical practice. Additionally, more focused research is needed to demonstrate the role of QOL, not only as an outcome in itself but also as a contributor to other outcomes, such as adherence to medications, more satisfaction, less resource utilization and so on. Since self-appraisal of QOL does not happen in a vacuum but relates to the total human experience in all its biological, psychosocial and environmental aspects, particular attention must also be focused on important neurobiological dimensions such as affect and cognition. Both are significantly affected by the illness itself and its treatment.

The construct validity of the health utilities index mark 3 in assessing health status in lung transplantation

Purpose

To assess the cross-sectional construct validity of the Health Utilities Index Mark 3 (HUI3) in lung transplantation.

Methods

Two hundred and thirteen patients (103 pre-transplant and 110 post-transplant) with mean age 53 years old (SD 13) were recruited during a randomized controlled clinical trial at the out-patient clinic in a tertiary institution. At baseline, patients self-completed measures that included the HUI3, EuroQol EQ-5D, Hospital Anxiety and Depression Scale (HADS) and socio-demographic questionnaire. Six-minute walk test scores and forced expiratory volume in 1 second data were collected from patient's medical records. A priori hypotheses were formulated by members of the transplant team about the expected degree of association between the measures. Correlation coefficients of < 0.1 were considered as negligible, 0.1 to < 0.3 as small, 0.3 to < 0.5 as medium, and ≥0.5 as large.

Results

Of the ninety predictions made, forty three were correct but in 31 the correlation was slightly lower than predicted and in 7 the correlations were much higher than predicted. In 48% of the cases, predicted and observed associations were in agreement. Predictions of associations were off by one category in 42% of the cases; in 10% of the cases the predictions were off by two categories.

Conclusions

This is the first study providing evidence of cross-sectional construct validity of HUI3 in lung transplantation. Results indicate that the HUI3 was able to capture the burden of lung disease before transplantation and that post-transplant patients enjoyed higher health-related quality of life than pre-transplant patients.

Sociodemographic and clinical correlates of utility scores in Alzheimer's disease

OBJECTIVES

To examine the relationship between psychiatric symptoms, cognitive performance, functional capacity and quality of life in Alzheimer's disease (AD), and change in the Health Utilities Index (HUI)-Mark III, a widely used generic, multiattribute preference-based health-status classification system.

METHODS

Follow-up data were obtained from caregiver proxy raters at 3, to 6, and 9-months postrandom assignment concerning 421 patients with AD, living with at least one caregiver in a noninstitutional setting, who participated in the Clinical Antipsychotic Trial of Intervention Effectiveness-AD of antipsychotic medication. Spearman rank correlations, multivariate linear regression, and mixed modeling were used to examine the correlates of change in the HUI.

RESULTS

HUI scores decreased by an average of -0.061 over 9 months. Analysis revealed weak bivariate, and largely, nonsignificant multivariate relationships between change in HUI scores and sociodemographic characteristics, psychiatric symptoms, and cognitive performance. There were highly significant associations between decreases in health utilities and change in the AD Cooperative Study for Activities of Daily Living scale (ADCS-ADL) and AD-Related Quality of Life (ADRQoL) (both P < 0.001), even after controlling for other factors. Adjusted R(2) values ranged from 0.14 to 0.20.

CONCLUSION

In AD patients requiring antipsychotic treatment, only weak relationships were found between changes in the HUI and sociodemographic and clinical indicators. While functional capability and quality of life showed more significant associations, less than 20% of the variance in health utility could be explained. Significant cognitive impairment and the need to rely on proxy raters may limit the usefulness of utility measurement in AD patients with serious behavioral symptoms.

The association of body mass index with health-related quality of life: an exploratory study in a multiethnic Asian population

OBJECTIVES

To evaluate the association between body mass index (BMI) and health-related quality of life (HRQoL) in a multiethnic Asian population in Singapore, and to explore if the World Health Organization (WHO) recommendation of alternative BMI cutoffs for Asians could be further strengthened by evidence of higher risk of impaired HRQoL using these criteria.

METHODS

Consenting English, Chinese, Malay and Tamil-speaking primary care patients (age >or= 21 years) were interviewed using English/their respective mother tongue versions of the EQ-5D/EQ-VAS, Health Utilities Index (HUI2 & HUI3) and the SF-6D. We first evaluated the relationship between BMI and HRQoL (overall and individual attributes for each instrument) using multiple linear/logistic regression (where appropriate) to adjust for factors known to affect HRQoL. We next reorganized BMI into five categories (reflecting the differences in cutoffs between International/Asian classifications) and evaluated if median HRQoL scores were significantly different across these categories.

RESULTS

Among 411 participants [response rate: 87%; median age: 51 years; obese: 19% (International); 33% (Asian)], after adjusting for sociodemographic and other factors, a tendency for underweight and obese subjects to report lower overall HRQoL scores was observed for most instruments. At the individual attribute level, obese subjects reported significantly lower HUI2 pain scores (regression coefficient: -0.035, P = 0.029) and greater odds of reporting problems for SF-6D role-limitations (odds ratio: 2.9, P = 0.005). Median overall HRQoL scores were not significantly different across the five BMI categories.

CONCLUSION

Consistent with available studies, obese subjects reported worse HRQoL than normal-weight subjects. That underweight subjects also reported worse HRQoL is interesting and requires confirmation. HRQoL was similar in Asians using either WHO criteria.