Aim: The aim of this paper is to develop an understanding of how behavioural theories have influenced
the way preferences for health-related quality of life are elicited and interpreted. We focus on the
Time Trade-off (TTO) method given it represents the quality-adjusted life-year (QALY) concept – that
survival in less-than-full ...
Aim: The aim of this paper is to develop an understanding of how behavioural theories have influenced
the way preferences for health-related quality of life are elicited and interpreted. We focus on the
Time Trade-off (TTO) method given it represents the quality-adjusted life-year (QALY) concept – that
survival in less-than-full health can be deemed equivalent to a shorter survival in full health. To our
knowledge this is the first review using a combination of systematic review, bibliometrics and
VOSviewer visualisation to map the development of ideas in health economics.
Methods: A priori, we selected three behavioural theories to explore within our review, referred to
here as Expected Utility Theory, Non-Expected Utility Theory and Probabilistic Choice Theory. A fourth
topic, Order Effects, is defined broadly to encompass behavioural theories around timing/sequence
of events. For the main search, Scopus was used to identify literature that had a) elicited TTO values
and/or b) contributed to the way TTO values were elicited and interpreted, from inception to July
2021. Papers that focused on the latter category were given the label ‘behavioural’ and underwent
additional analyses. A two stage-screening was applied to assess eligibility. Co-citation, co-authorship
and co-occurrence of keywords was used to chart the development of TTO over time.
Results: A total of 1,727 records were retrieved from Scopus and were supplemented by an additional
188 papers from Spencer et al. 2021 There were 856 applied and 280 behavioural papers included in
the final corpus, with the behavioural set split equally into four sets of 70 papers to chart the
development of keywords over time: 1) 1972-1999; 2) 2000-2010, 3) 2010-2015 and 4) 2015-2021.
Discussion: The keyword analysis suggested that whilst some ideas transition quickly from economic
theory to the TTO literature, such as the impact of Order Effects, others take longer to be assimilated,
for example Non-Expected Utility models or failure of constant discounting. It is therefore important
that researchers within health economics work more closely with those in mainstream economics and
keep abreast of the wider economics and behavioural sciences to expedite the uptake of new and
relevant ideas.
