Original Article
Validity and reliability of the EQ-5D-3L (a generic preference-based instrument used for calculating quality-adjusted life -years) for patients with type 2 diabetes in Iran

https://doi.org/10.1016/j.dsx.2021.01.009Get rights and content

Highlights

  • •EQ-5D-3L is a generic preference-based instrument used for calculating quality-adjusted Life -years

  • The EQ-5D-3L Iranian Version demonstrated reliability and construct validity in patients with type 2 diabetes.

  • •The EQ-5D-3L has ceiling effects higher than 15% in Iranian patients with type 2 diabetes.

  • •The instrument could be used for other regions of the Middle East.

Abstract

Background and aims

The psychometric properties of the EQ-5D-3L (a generic preference-based instrument used for calculating quality-adjusted Life –years) have not been known for any type of disease in Iran. This study aimed to assess its validity and reliability in patients with type 2 diabetes.

Methods

Data of 579 patients were collected from the Diabetes Research Center and Clinics in Yazd using EQ-5D-3L, SF-36, and DQoL instruments. The ceiling effects were computed for the EQ-5D-3L index and EQ VAS. The construct validity was assessed by using convergent validity, discriminant validity, and known-groups validity. Reliability was assessed using Cohen’s kappa value, Cronbach’s alpha, and intra-class correlation coefficient.

Results

The ceiling effects of EQ-5D-3L and EQ VAS were 20.18% and 15.33%, respectively. The highest degree of correlation was found between the pain/discomfort of EQ-5D and the BP scale of the SF-36 (0.55). Higher scores of all scales of the DQoL were associated with patients reporting no problems in each EQ-5D dimension. The mean of EQ-5D-3L index and EQ VAS scores were significantly higher in the male, married, and employed patients, and they did not have retinopathy, nephropathy, IHD, hypertension, DFU. The range of kappa values was from 0.39 to 0.71, and value of ICC for the EQ-5D-3L index and EQ VAS was 0.76 and 0.64, respectively. Cronbach’s alpha was 0.87 for EQ-5D-3L and 0.74 for EQ VAS.

Conclusions

Our findings demonstrated good construct validity and moderate to good levels of reliability of the EQ-5D-3L for using in the patients with diabetes, and it can be used in research or clinical practice in Iran and other regions of the Middle East.

Section snippets

introduction

The Middle East and North Africa (MENA) region has the highest age-adjusted diabetes prevalence (12.2%) of all the International Diabetes Federation Regions. Globally, diabetes-related health expenditure in the MENA region was USD 24.9 billion in 2019 and is expected to increase by 30.3% to USD 32.5 billion by 2030 [1]. The high prevalence of the disease and its high health expenditures impose economic burdens on healthcare system of countries in this region such as Iran. It seems that economic

Study design and data collection

This cross-sectional survey was conducted on 590 type 2 diabetes patients who referred to the Diabetes Research Center and Clinics in Yazd. Yazd, a world heritage city, is located in center of Iran. According to a report by WHO, it has the highest prevalence of DM based on HbA1c among cities of Iran [12]. The center is one of the most important centers in Iran that provides specialized services for the patients of diabetes and covers over 10,000 diabetic patients. The patients were selected

Results

Totally, data of 11 patients were excluded from the study because of missing more than 20% of the responses on items of the SF-36 and DQoL questionnaires. Thus, characteristics of 579 patients included in the final analysis of the initial survey (Table 1). The mean age of patients was 59.4 years (SD 20), and mean of WHR, duration of diabetes, and HbA1c level was 0.98(0.38), 8.40 years (5.61) and 8.58 (1.90), respectively (Table 1).

Out of 110 patients who were selected for the repeated survey,

Discussion

In this study, the psychometric properties of the EQ-5D-3L were evaluated among type 2 diabetes patients with a variety of socio-demographic and clinical characteristics. This study was conducted on a large sample size based on the COSMIN study design checklist for patient-reported outcome measurement instruments [23], and is, to the best of our knowledge, the first study assessing the psychometric aspects of the EQ-5D-3L in a country of the Middle East region whose value set was generated in

Conclusion

This is the first report of the validity and reliability of EQ-5D-3L for any type of disease in Iran and Middle East region.The findings of convergent, discriminant, and known-groups validity support the construct validity of the EQ-5D for use in type 2 diabetes patients, while the ceiling effects are relatively high for the instrument. In addition, we found that criterion of the reliability was moderate to good levels. Thus, the construct validity and reliability of the EQ-5D-3L were both

Authors’ contributions

HA conceptualized the study and the design of study. HA, FA and FM participated in data analysis and data interpretation. HA and M R-A wrote the original draft of the manuscript. All authors read and approved the final manuscript.

Compliance with ethical standards

This report is part of a MSc project that was approved by the committee of Shahid Sadoughi University of Medical Sciences (registration number: IR.SSU·SPH.REC.1398.134). Informed consent was completed for each patient.

Funding

This study was funded by Shahid Sadoughi University of Medical Sciences (grant number: 6843).

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

The authors hereby bestow much gratitude to the departments of Diabetes Research Center and Clinics in Yazd for their valuable collaboration in the present study. We express our gratitude to Shahid Sadoughi University of Medical Sciences (grant number: 6843) that provide fund for this project.

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