Methods Used to Identify, Test, and Assess Impact on Preferences of Bolt-Ons: A Systematic Review [Editor's Choice]

Jun 1, 2021, 00:00 AM
Section Order : 901
First Page : 901


The question of whether additional dimensions should be added to the EQ-5D, so-called bolt-ons, has been researched since the 1990s. Several candidate bolt-ons have been tested. The aim of this systematic review was to provide an overview of EQ-5D bolt-on studies, including the origin of possible suitable bolt-ons, their format, and methods that were used to examine their value.


Studies were identified through database search and reference screening and assessed based on a set of inclusion criteria. All studies that investigated bolt-ons for the EQ-5D were eligible for inclusion. Two reviewers independently extracted information from all included studies on objectives, study design, EQ-5D version used, the investigated bolt-ons, methods used to achieve objectives, and outcomes.


Of 308 initially identified studies, 28 studies met the inclusion criteria. Of these studies, 3 identified potentially suitable bolt-on dimensions, 13 investigated the psychometric performance of EQ-5D + bolt-on(s), and 6 investigated the impact of the bolt-on on health state preferences. In total, 26 bolt-ons were identified, of which cognition was the most frequently mentioned. A wide variety of bolt-on identification methods, psychometric performance tests, and health state valuation methods were used in the included studies.


A range of bolt-on dimensions has been investigated using diverse methods. Guidelines are needed to standardize the wording of the bolt-on dimension and response options, evaluate minimal important gain of the bolt-on, and facilitate quality assessment of bolt-on studies. Subsequently, guidelines will facilitate decision making on whether or not to implement a bolt-on dimension to the EQ-5D.
HEOR Topics :
  • Health State Utilities
  • Instrument Development, Validation, & Translation
  • Literature Review & Synthesis
  • Patient-Centered Research
  • Patient-reported Outcomes & Quality of Life Outcomes
  • Stated Preference & Patient Satisfaction
  • Study Approaches
Tags :
  • bolt-on
  • EQ-5D
  • systematic review
Regions :