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Table 1 Summary of the characteristics of EuroQol protocols

From: EuroQol Protocols for Time Trade-Off Valuation of Health Outcomes

  Protocol
MVH Paris EQ-VT
TTO framework
 Framework Conventional TTO Composite TTO
 Anchor states 11111 (‘no problems in walking about; washing or dressing oneself; and performing usual activities; no pain or discomfort; not anxious or depressed’) and ‘death’ ‘Full health’ and ‘death’
 Time horizon 10 years for both BTD and WTD states 10 years for BTD states; 20 years for WTD states
 Structure of the hypothetical lives For BTD states: Life A—living in full health for x years followed by death (alternative 1); Life B—living in the impaired state for 10 years followed by death (alternative 2)
For WTD states: Life A—living in the impaired state for 10 − x years, then full health for x years followed by death (alternative 1); immediate death (alternative 2)
For BTD states: Life A—living in full health for x years followed by death (alternative 1); Life B—living in the impaired state for 10 years followed by death (alternative 2);
For WTD states: Life A—living in full health for x years followed by death (alternative 1); Life B—living in full health for 10 years, then the impaired state for 10 years followed by death (alternative 2)
Iteration procedures and mode and method of administration
 Iteration starting point 10 years
 Iteration algorithm Bisection for the first three steps followed by upward/downward titration with 1-year increments and a correction of 6 months when preference reversal occurs Bisection for the first three steps followed by upward/downward titration with 1-year increments without any correction Bisection for the first three steps followed by upward/downward titration with 1-year or 6-month increments and corrections of 6 months whenever preference reversal occurs
 Iteration termination rule Indifference/indifference range = 6 months Indifference/indifference range = 1 year Indifference
 Mode of administration Face-to-face, one-on-one personal interviewing Face-to-face, one-on-one computer-assisted personal interviewing
 Method of administration and visual aids Paper-and-pencil with a time board as the visual aid Electronic data collection and digital presentation of the visual aid
Training and quality control
 Respondent training Ranking and VAS-based warm-up tasks plus explanation of TTO by interviewer One example and three practices
 Interviewer training Interviewer training workshop (unstandardized) Interviewer training workshop (unstandardized)
 Quality control No quality control procedure was formalised and included in the protocol Standardised quality control software
  1. BTD better than death, EQ-VT EuroQol valuation technology, MVH measurement and valuation of health, TTO time trade-off, VAS visual analogue scale, WTD worse than death