Exploring the Comparability of Face-to-Face Versus Video Conference-Based Composite Time Trade-Off Interviews: Insights from EQ-5D-Y-3L Valuation Studies in Belgium and Spain

Abstract

Background: Face-to-face interviews are recommended for the collection of composite time trade-off (cTTO) data. The coronavirus disease 2019 (COVID-19) social distancing measures made researchers consider videoconferencing interviews as an alternative mode of administration, but little evidence about the implementation of videoconferencing in valuation studies is available. This study provides insights into the effect of videoconferencing on the quality of data, evaluating interviewers' and respondents' engagement level in videoconferences compared with face-to-face interviews.

Methods: We used cTTO data collected in Belgium and Spain following the EQ-5D-Y-3L valuation protocol. Due to the COVID-19 pandemic, both projects interrupted the face-to-face data collection before reaching the target sample. The remaining interviews were conducted by videoconference. We compared both modes of administration in terms of interviewers' engagement (task duration and number of moves in each example) and respondents' engagement (task duration and proportions of specific response values, in half-year units). To minimise interviewers' learning effects, we split our sample into three groups: (1) first 20 interviews conducted face-to-face; (2) subsequent interviews conducted face-to-face; and (3) videoconferencing interviews.

Results: The comparison between videoconferencing and subsequent face-to-face interviews showed the interviewer's engagement was not affected by the mode of administration as almost no significant results were found either in the task duration or the numbers of moves shown in the examples. Similarly, none of the respondents' task duration or proportion of specific responses or half-year units were affected by the mode of administration in either of the two countries.

Conclusions: No evidence suggested that the quality of cTTO data is reduced when using videoconferencing compared with face-to-face interviews.

Fig. 1

cTTO task example. a Better than dead side; b worse than dead side; c iteration procedure. The iteration procedure used to vary t is described elsewhere [12], but briefly, it uses a ping-pong approach starting with t in 10 years (t = 10 years in full health = ‘Life A’ and 10 years in the impaired health state = ‘Life B’) and moving to t = 0 if a respondent chooses A. If the respondent then chooses B, t is increased to t = 5 (a) followed by 1-year increments/decrements or 6-month increments/decrements depending on respondent’s choices. If at t = 0 the respondent chooses A, the worse-than-dead side of the task is shown (b), where t = 10. If the respondent chooses A again, t is decreased to t = 5 followed by 1-year increments/decrements or 6-month increments/decrements depending on the respondent’s choices. Utilities shown in Fig. 1c for the impaired health states are calculated using t of the point of indifference: U = t/10 for states considered better-than-dead, and U = (t-10)/10 for states considered worse-than-dead. cTTO composite time trade-off

Fig. 1

cTTO task example. a Better than dead side; b worse than dead side; c iteration procedure. The iteration procedure used to vary t is described elsewhere [12], but briefly, it uses a ping-pong approach starting with t in 10 years (t = 10 years in full health = ‘Life A’ and 10 years in the impaired health state = ‘Life B’) and moving to t = 0 if a respondent chooses A. If the respondent then chooses B, t is increased to t = 5 (a) followed by 1-year increments/decrements or 6-month increments/decrements depending on respondent’s choices. If at t = 0 the respondent chooses A, the worse-than-dead side of the task is shown (b), where t = 10. If the respondent chooses A again, t is decreased to t = 5 followed by 1-year increments/decrements or 6-month increments/decrements depending on the respondent’s choices. Utilities shown in Fig. 1c for the impaired health states are calculated using t of the point of indifference: U = t/10 for states considered better-than-dead, and U = (t-10)/10 for states considered worse-than-dead. cTTO composite time trade-off

Fig. 2

cTTO value distribution for all health states. *There were not significant results at the 95% confidence interval from the proportions test. cTTO composite time trade-off

Fig. 3

cTTO value distribution for each interviewer. *There were not significant results at the 95% confidence interval from the proportions test. cTTO composite time trade-off