A systematic review of the use of an expertise-based randomised controlled trial design

Abstract
Background
Under a conventional two-arm randomised trial design, participants are allocated to an
intervention and participating health professionals are expected to deliver both interventions.However, health professionals often have differing levels of expertise in a skill-based interventions such as surgery or psychotherapy. An expertise-based approach to trial design,
where health professionals only deliver an intervention in which they have expertise, has
been proposed as an alternative. The aim of this project was to systematically review the use
of an expertise-based trial design in the medical literature.
Methods
We carried out a comprehensive search of nine databases—AMED, BIOSIS, CENTRAL,
CINAHL, Cochrane Methodology Register, EMBASE, MEDLINE, Science Citation Index,
and PsycINFO—from 1966 to 2012 and performed citation searches using the ISI Citation
Indexes and Scopus. Studies that used an expertise-based trial design were included. Two
review authors independently screened the titles and abstracts and assessed full-text reports.
Data were extracted and summarised on the study characteristics, general and expertisespecific
study methodology, and conduct.
Results
In total, 7476 titles and abstracts were identified, leading to 43 included studies (54 articles).
The vast majority (88 %) used a pure expertise-based design; three (7 %) adopted a hybrid
design, and two (5 %) used a design that was unclear. Most studies compared substantially
different interventions (79 %). In many cases, key information relating to the expertise-based
design was absent; only 12 (28 %) reported criteria for delivering both interventions. Most
studies recruited the target sample size or very close to it (median of 101, interquartile range
of 94 to 118), although the target was reported for only 40 % of studies. The proportion of
participants who received the allocated intervention was high (92 %, interquartile range of 82
to 99 %).
Conclusions
While use of an expertise-based trial design is growing, it remains uncommon. Reporting of
study methodology and, particularly, expertise-related methodology was poor. Empirical
evidence provided some support for purported benefits such as high levels of recruitment and
compliance with allocation. An expertise-based trial design should be considered but its value
seems context-specific, particularly when interventions differ substantially or interventions