Methodological quality of the review: Low
Author: Janssen MF, Lubetkin EI, Sekhobo JP, Pickard AS.
Region: United States of America (USA) and Europe
Sector: Diabetes Mellitus, EQ-5D
Sub-sector: Preference-based health status measure
Equity focus: None Specified
Review type: Effectiveness review
Quantitative synthesis method: Meta- analysis
Qualitative synthesis methods: Not applicable
The EQ-5D is a generic preference-based health status measure that has been applied to measure the impact of type 2 diabetes mellitus. It is the most widely used preference-based health status measure, which offers a condensed format and ‘global appeal through translations and value sets’. It has been used globally, in patients with diverse illnesses. The EQ-5D describes and values health status in terms of five dimensions: Mobility, Self-Care, Usual Activities, Pain/Discomfort and Anxiety/Depression.
To summarize evidence on the validity, reliability and responsiveness of the EQ-5D in studies of type 2 diabetes and to provide a catalogue of EQ-5D index scores for type 2 diabetes and various complications and sub-groups.
The review identified 59 studies for inclusion, of cross-sectional, experimental or longitudinal design. Of the 59 included articles, 54 publications reported on EQ-5D index score, visual analogue scale (VAS) score and/or responses to the self-classification system, and 39 papers presented evidence of the measurement properties of the EQ-5D. The majority of studies were cross-sectional (31) and 10 studies followed an experimental design.
Authors reported the following results:
‘Studies that reported measurement properties supported construct, convergent and discriminant validity, test-retest reliability and responsiveness of the EQ-5D in type 2 diabetes. Several studies reported a ceiling effect for the EQ-5D and an inability to capture multiple complications was observed. EQ-5D index scores ranged from 0.20 (severe diabetic peripheral neuropathic pain) to 0.88 (general population: good HbA1c level). For six sub-groups, sufficient studies were available to calculate pooled mean index scores (95% CI): general population 0.67 (0.59-0.75), no complications 0.76 (0.68-0.83), microvascular complications 0.73 (0.57-0.89), macrovascular complications 0.73 (0.57-0.88), diabetic peripheral neuropathic pain 0.45 (0.39-0.51) and retinopathy (0.46-0.69)’.
Authors concluded that ‘Evidence from this review supports the validity, reliability and responsiveness of the EQ-5D in type 2 diabetes. EQ-5D index scores associated with type 2 diabetes and various complications can be useful for modelling health outcomes in economic evaluations of health programs for type 2 diabetes.’
Authors noted that future research should assess head-to-head comparisons of the EQ-5D with other health-related quality of life instruments, as well as investigate the ability of the EQ-5D to track the health-related quality of life of patients with type 2 diabetes who transition from one health state to another within and across specific diabetes related complications using longitudinal study designs.
Review authors conducted a search of MEDLINE and EMBASE from 1987 to January 2009. Additionally, the EuroQol website and the research databases of the International Diabetes Federation, American Diabetes Federation and the European Association for the Study of Diabetes were used to identify unique references that may have not been identified on the first search. Authors’ libraries were also searched by hand. Bibliographies of articles identified through the computer searches were also reviewed to identify additional articles that reported on the EQ-5D. Only studies written in English and Spanish were included in the review. All identified articles were reviewed by three independent reviewers. Studies were included if they reported EQ-5D measurement properties or scores on the EQ-5D index, VAS or percentage dimension scores, or the relative impacts on utilities of specific complications. No other restrictions were applied.
A meta-analysis was used and a calculation of pooled means was possible for six sub-groups of Type 2 diabetes: general population, no complications, microvascular complications, macrovascular complication, diabetic peripheral neuropathic pain and retinopathy.
Authors did not discuss the applicability/external validity of the results.
The geographical location was not reported for all studies, only for those conducted in the USA and Europe.
A low confidence was attributed in the conclusions about the effects of this study. The literature search did cover relevant databases and reference lists in included studies, but the authors/experts were not contacted as part of the search strategy and language bias was not avoided. Authors used appropriate methods to reduce risk of bias in terms of study selection and data extraction of included studies, however it was not clear if authors assessed the quality and risk of bias of included studies. Authors conducted a meta-analysis by sub-group, which seemed appropriate given the different classifications of complications and co-morbidities used by included studies. Nevertheless, it should be noted that this included experimental, cross-sectional and longitudinal studies.