CHAPTER 94: EQ-5D AND EQ-VAS

Description

The EQ-5D and EQ-VAS are both utility-based questionnaires and visual analog scales (VAS) of health-related quality of life (HRQoL), which, according to Patrick and Erickson (1993), is the particular value assigned to the duration of survival as modified by impairments, functional states, perceptions, and social opportunities influenced by disease, injury and treatment. Developed by the EuroQol Group, the EQ-5D is a 5-item, 3-choice response assessment of an individual’s HRQoL and is based according to a person’s subjective view of the following attributes: mobility, self-care, usual activities, pain, anxiety, and depression (Davis, Liu-Ambrose, Richardson, & Bryan, 2013). Although, it seems to be a relatively simple 5-item assessment, the EQ-5D employs a distinctive scoring algorithm that has the ability to describe 243 unique health states, which, in turn, yields a single summary score between –1 and +1 that defines a person’s health state. The summary scores can then be used to facilitate comparisons across different health conditions and patient population norms, with higher scores indicative of a better quality of life (QoL). A 5-response assessment, as opposed the to 3-response system discussed previously, is also available in the EQ-5D-5L, which is designed to have better discriminative capacity and sensitivity to change than the EQ-5D, as well as smaller ceiling effects (Davis et al., 2013). Like the original, respondents record their level of problems experienced in the same 5 questions of health; however, they choose between 5 levels of health outcomes: (1) no problem, (2) slight problem, (3) moderate problem, (4) severe problem, or (5) extreme problem. Based on the new combination of responses, respondents can be classified into one of 3125 unique health-state profiles (Fogarty et al., 2013). The accompanying EQ-VAS of both outcome measures is a simple VAS where a client is asked to gauge his or her current health state between best and worst imaginable, which can then be used by the practitioner as a subjective quantitative measure of well-being. Example items of the 3-response test are as follows:

• Mobility
  
  
  
  • (1) I have no problems in walking about
    
  • (2) I have some problems in walking about
    
  • (3) I am confined to bed
  
  
• Pain/discomfort
  
  
  
  • (1) I have no pain or discomfort
    
  • (2) I have moderate pain or discomfort
    
  • (3) I have extreme pain or discomfort.

The EQ-5D battery can be completed in less than 5 minutes.

Psychometrics

Results from a multinational study of healthy individuals found that test–retest agreement from an Italian sample was r = 0.83 with a range of 0.70 to 0.94 for each dimension. The highest score was for looking after oneself and the lowest was for pain or discomfort. Results from a Spanish study were similar with test-retest agreement of r = 0.94 and a range of 0.86 (pain or discomfort) to 0.99 (looking after oneself). A study of subjects with a major neurocognitive disorder found that item intra-class correlation coefficients of the test were r = 0.72, with an internal consistency Cronbach’s alpha of α = 0.64, while item/total correlation ranged from 0.33 to 0.53 (Diaz-Redondo, Rodriguez-Blazquez, Ayala, Martinez-Martin, & Forjaz, 2014). A study by Fogarty et al. (2013) of multiple sclerosis patients, found that the EQ-5D-5L (5-response assessment) displayed good discriminatory capacity with performance differing between the various domains of health; however, evidence of a ceiling effect was noted for self-care and anxiety/depression. A stepwise regression model by Hurst, Kind, Ruta, Hunter, and Stubbings (1997) showed that EQ-5D utility values and VAS were explained best as a function of pain, disability, disease activity, and mood while other variables (side-effects, years of education) were needed to explain the VAS.

Advantages

The EQ-5D and associated scales are simple and easy to administer and can be completed in less than 5 minutes. There is also a large amount of research in support of their use in clinical practice. Both the EQ-5D and EQ-5D-5L (3- and 5-response assessments) and EQ-VAS have shown to be culturally relevant measures with published norms available for many countries. The EQ-5D and EQ-5D-5L employ unique scoring systems that are able to deliver 243 and 3125 different possible health states according to a designed algorithm. The EQ assessments can also be used across various patient populations as well as research settings. Finally, the EuroQol Group has an excellent interactive website devoted to these and other standardized assessments they have created.

Disadvantages

The EQ-5D batteries contain only 5 health-related questions and although they use unique scoring systems they may be considered by some to be only quick screens to determine if a more thorough investigation is warranted. Fees are required to use either EQ-5D versions in private practice depending on the size of the entity where it is to be used as well as the mode(s) of administration (i.e., paper covering telephone scripts, PDA, tablet or Web-based).

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