Development of a Method for Converting Visual Analogue Scale (VAS) Scores for Pain and Mobility to EQ-5D Answers

Study Overview
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Brief Summary
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The objective of this study is to investigate how mobility and pain scores, measured on a Visual Analogue Scale (VAS), correspond to patients' EuroQol-5Dimensions-3Levels (EQ-5D-3L) answers on pain and mobility. In addition, the investigators want to evaluate patients' undergoing Coronary Artery Bypass Grafting (CABG) quality of life postoperatively, depending on the vein harvesting method used.

Detailed Description
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Many health economic researchers prefer that a treatments effect is measured in the quantity and quality of life (Qol) the treatment provides. This enables them to calculate effect in the generic Quality Adjusted Life-Years (QALYs). Patients' Qol can be estimates by having patients' answer the EQ-5D-3L questionnaire. However, when performing a post hoc health economic evaluation, data is often incomplete. Often there is no information available regarding the patients' Qol and some health economic researchers therefore resort to various conversions of other measurements of effect to Qol. Such conversions thereby enable them to calculate effect in QALYs even though they had incomplete information. However, no method has been developed for converting eg. VAS pain scores to Qol and the methods currently used are arbitrary. With this study the investigators wish to develop such a method and in the process evaluate our own arbitrary Qol conversion from a prior study by asking the same type of patients. The study is an observational study with no intervention.

Official Title
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Development of a Method for Converting VAS Scores for Pain and Mobility to EQ-5D Answers

Conditions
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Cardiovascular Diseases

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Elective CABG patients Use of a vein segment for conduit during CABG

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Endoscopic Vein Harvest (EVH)<br>A short saphenous vein segment is commonly used as a conduit for coronary artery bypass grafting (CABG), and clinicians must decide whether to obtain it by performing a traditional open vein harvest (OVH) or by performing an endoscopic vein harvest (EVH). | |
| Open Vein Harvest (OVH)<br>A short saphenous vein segment is commonly used as a conduit for coronary artery bypass grafting (CABG), and clinicians must decide whether to obtain it by performing a traditional open vein harvest (OVH) or by performing an endoscopic vein harvest (EVH). | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The distribution of answers to EQ-5D-3L sub-questions on a 100mm VAS for each sub-question. | The investigators wish to investigate how patients scoring no pain or discomfort, moderate pain or discomfort and extreme pain or discomfort on the EQ-5D questionnaire score their pain on a 100mm VAS of pain. The same is done for the four other sub-questions in the EQ-5D, eg. how do patients score their mobility on a 100mm VAS of mobility if they score no problems in walking about, some problems in walking about or confined to bed on the EQ-5D. (see citations for similar study setups) | Approximately five days postoperatively | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Quality of life (Qol) | The investigators will obtain 3 measurements from each patient and are therefore able to evaluate the change in Qol from baseline to approximately 30 days postoperatively in a group of elective bypass patients. Investigators hereby aim to find the incremental Qol. The patient group will be segmented on whether they underwent endoscopic or open vein harvest during their surgery. | approximately 30 days | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Qol, Quality of life, VAS, Visual Analogue Scale, CABG, Coronary Artery Bypass Graft, Qol conversion, post hoc HTA