Strenghts and limitations
Our study has a number of strengths. First, we investigated recruitment
failure in 83 RCTs embedded within the Dutch Consortium for Women’s
Health Research – and thus within one discipline - with support and
monitoring by the clinical trial centre. This allowed us to standardize
several important aspects, like trial management and logistics, data
collection and data monitoring. Second, we were able to assess all
indicators with a potential association with poor recruitment as
described in literature; type of investigation, placebo-controlled
study, treatment versus no treatment, whether the intervention was new
or only available in the trial, whether the study was blinded or if
there were any competing RCTs, number of study arms, number of inclusion
and exclusion criteria, whether a pilot study was performed, number of
participating centres and funding and compensation per included patient.
The main limitation of our study is the number of trials. Obviously, if
we could have accessed an even larger cohort of trials, we might have
been able to identify more potential indicators for recruitment failure.
A further limitation may be that within our study we focussed on
objective indicators, such as trial logistics and design issues. Other
aspects, like patients’ or practitioners’ perspectives, which may affect
recruitment as well were beyond the scope of our study.