The added value of the EQ-5D with a cognition dimension in injury patients with and without traumatic brain injury
Quality of Life Research
pp 1–9 | Cite as
The added value of the EQ-5D with a cognition dimension in injury patients with and without traumatic brain injury
AuthorsAuthors and affiliations
A. J. L. M. GeraerdsGouke J. BonselMathieu F. JanssenM. A. de JonghInge SpronkSuzanne PolinderJuanita A. Haagsma
Open Access
Article
First Online: 28 February 2019
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Abstract
Purpose
This study investigated the psychometric gain, if any, from the extension of the EQ-5D with a cognition bolt-on (EQ-5D + C) in a large cohort injury patients with and without traumatic brain injury (TBI).
Methods
Hospitalized adult injury patients filled out a survey 1 month after initial admission. The survey included the EQ-5D-3L, the cognition bolt-on item in EQ-5D format, and the visual analogue scale (EQ-VAS). We compared ceiling and other distributional effects between EQ-5D and EQ-5D + C and TBI and non-TBI group, and assessed convergent validity using the predictive association with EQ-VAS. Also, we assessed explanatory power using regression analysis, and classification efficiency using Shannon indices.
Results
In total, 715 TBI patients and 1978 non-TBI patients filled out the EQ-5D + C and EQ-VAS. Perfect health was reported by 7.9% (N = 214) on the EQ-5D, and 7.3% (N = 197) on the EQ-5D + C. Convergent validity was highest for EQ-5D + C in the TBI group (Spearman’s rank correlation coefficient = − 0.736) and lowest for EQ-5D in the non-TBI group (Spearman’s rank correlation coefficient = − 0.652). For both TBI and non-TBI groups, the explanatory power of EQ-5D + C was slightly higher than of EQ-5D (R2 = 0.56 vs. 0.53 for TBI; R2 = 0.47 vs. 0.45 for non-TBI). Absolute classification efficiency was higher for EQ-5D + C than for EQ-5D in both TBI groups, whereas relative classification efficiency was similar.
Conclusions
Psychometric performance in general of both the EQ-5D and EQ-5D + C was better in TBI patients. Adding a cognitive bolt-on slightly improved the psychometric performance of the EQ-5D-3L.
KeywordsHRQoL EQ-5D Cognition TBI
Background
Currently, the measurement of health-related quality of life (HRQoL) is standard practice in evaluating the impact of health interventions [1]. HRQoL instruments can be categorized as generic and disease-specific measures, where a particular subclass of instruments are preference-based or ‘utility’ measures, which can be used in economic evaluations [2].
One of the generic instruments that is widely implemented is the EQ-5D. The EQ-5D is a self-assessment instrument that consists of five items on the following dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression and a visual analogue scale (VAS) [3]. The five dimensions can be scored using 3- or 5-level ordinal response options. One major advantage of the EQ-5D over other generic HRQoL measurement instruments is its brevity and subsequent low burden to fill out [4, 5]. However, a downside of the brevity may be that important information for HRQoL is not included in the EQ-5D dimensions, resulting in an instrument that may be unable to capture certain health effects and that is not sensitive for the measurement of HRQoL of all conditions [6, 7]. Moreover, the EQ-5D is known to measure mainly physical dimensions of health, and lacking information on social domains and sensitivity on psychological domains. Therefore, the EQ-5D is inconsistent in some populations [8]. A solution to increase coverage of the EQ-5D may be to add a dimension (a ‘bolt-on’) covering a specific health problem or dysfunction relevant to any particular condition or disease [9].
Over time, different bolt-on items to enrich the EQ-5D have been suggested. One of these bolt-on items is cognition [10]. Cognition can be operationalized with attributes like concentration, memory, intellectual competence, and coherence [10]. A cognition bolt-on can be motivated from theoretical reasons or from the pragmatic observation that cognition affecting diseases and conditions are common (dementia, Parkinson’s disease, injury, birth trauma, and congenital neurological conditions).
Even though many studies already use the cognition bolt-on in the measurement of HRQoL with the EQ-5D, limited evidence on the added value of the cognitive bolt-on in patient groups with cognitive impairments exists. Wolfs et al. [11] found that in a population of elderly patients with cognitive impairments, the addition of a cognitive dimension had no effect on the construct validity. Ophuis et al. (Working paper: Health-related quality of life in injury patients: the added value of extending the EQ-5D-3L with a cognitive dimension) found that adding a cognition dimension to the EQ-5D in a heterogeneous sample of injury patients, including patients with mostly mild traumatic brain injury (TBI), had a similar impact on EQ-VAS scores as any of the existing five EQ-5D dimensions. However, both studies were lack (...truncated)