=====EQ-5D (EuroQoL–5 Dimension health survey)=====
Instrument for measuring [[HRQOL]].

It consists of a 5-dimensional questionnaire measuring mobility, selfcare, usual activities, pain/discomfort, and anxiety/depression. Every dimension can be scored using 3 levels: no problem, some or moderate problems, and extreme problems, corresponding to a score. This gives 243 different
health status combinations that can be converted into an index value. 

The value is based on data generated from a national general public survey using the time-trade-off
(TTO) method to elicit mean TTO values to each health state. Since there is no Swedish TTO tariff for EQ-5D health states, the UK EQ-5D index tariff was used.

EQ-5D also contains a visual analog scale (EQ-VAS) with which patients can rate their HRQOL from 0 to 100,
where 0 is the worst imaginable health state and 100 the best imaginable health state. Improvement is defined as a gain of 0.05 index points or 10 points on EQ-VAS. 

http://www.euroqol.org/about-eq-5d.html


The European Quality of Life Questionnaire 5 level version (EQ-5D-5L) is a recently updated instrument to assess [[Health]]-Related [[Quality of Life]] (HRQoL) that has not been validated extensively.

The [[EQ-5D]]-3L essentially consists of 2 pages - the EQ-5D descriptive system (page 2) and the EQ visual analogue scale (EQ VAS) (page 3). The EQ-5D-3L descriptive system comprises the following 5 dimensions: mobility, self-care, usual activities, pain/discomfort and anxiety/depression. Each dimension has 3 levels: no problems, some problems, extreme problems. 

http://www.euroqol.org/about-eq-5d/how-to-use-eq-5d.html


====Parkinson's disease====
In a [[Cross-sectional study]], consecutive Mexican subjects with [[Parkinson's disease]]. HRQoL was assessed using the EQ-5D-5L and the PDQ-8. Validity of the EQ-5D-5L was assessed determining its association with clinical ratings of disease severity, as well as correlation with PDQ-8. Additionally, performance was evaluated along predefined groups based on clinical and demographic data of known determinants of quality of life.

A total of 585 patients were included for this study. A strong correlation was found between EQ-5D-5L index and [[PDQ 8]] index (Spearman's correlation coefficient=-0.75; p<0.001). Correlation between EQ-5D-5L index and PDQ-8 index remained strong (-0.60 to -0.78; p values <0.001) through all predefined groups. EQ-5D-5L scored higher in those patients with dyskinesia, wearing off, freezing, postural instability, cognitive impairment or depressive mood (p values <0.001).

The EQ-5D-5L is a valid instrument for evaluating HRQoL in PD, performing adequately irrespective of heterogeneous clinical and demographic characteristics, and showing to be sensitive to features of advanced disease and treatment complications
((Alvarado-Bolaños A, Cervantes-Arriaga A, Rodríguez-Violante M, Llorens-Arenas 
R, Calderón-Fajardo H, Millán-Cepeda R, Leal-Ortega R, Estrada-Bellmann I,
Zuñiga-Ramírez C. Convergent validation of EQ-5D-5L in patients with Parkinson's 
disease. J Neurol Sci. 2015 Aug 7. pii: S0022-510X(15)00503-1. doi:
10.1016/j.jns.2015.08.010. [Epub ahead of print] PubMed PMID: 26276513.)).

====Metastatic spine disease====
The [[Spine Oncology Study Group Outcome Questionnaire]] (SOSG-OQ) is superior to the EQ-5D in terms of coverage and internal consistency, but consists of more questions
((Janssen SJ, Teunis T, van Dijk E, Ferrone ML, Shin JH, Hornicek F, Schwab JH. 
Validation of the Spine Oncology Study Group Outcomes Questionnaire to assess
quality of life in patients with metastatic spine disease. Spine J. 2015 Aug 5.
pii: S1529-9430(15)01197-3. doi: 10.1016/j.spinee.2015.07.456. [Epub ahead of
print] PubMed PMID: 26254565.
)).