Apologies for cross-posting.
Dear Group Members,
Randomized clinical trials (RCTs) are considered the gold standard in
establishing efficacy of therapeutic interventions. Often considerable
financial interest hinges on the “statistical significance” of results or
lack thereof. At the same time, more “observational” patient level data is
becoming available for health outcomes research and it is expected that
such data will increasingly be considered to inform recommendations and
decision making in health care, public or private. Economic data can be
derived from both RCTs and observational studies.
The claim that RCTs always stand higher in the hierarchy of evidence
relative to observational studies has been axiomatic and remains
undisputed, particularly in the medical world. Many philosophers and
statisticians, however, do not seem to agree. While there is consensus
that good studies, RCTs or otherwise, are those with less bias, there are
numerous examples of unbalanced and biased RCTs, as well as very well
designed cohort studies. According to some authors, notably John Worrall
(LSE), randomization itself offers little advantage, and we can never be
sure that the groups are balanced for all known and unknown factors. The
argument that randomization specifically takes care of the unknown
confounders in by no means convincing. While blinding is valuable, thst
can not always be said of randomization. Bayesian statisticians seem to
have been able to deal with issues of correlation versus causality in
clinical trials without resorting to randomization.
That said, there is no reason to claim that the actually conducted RCTs
and observational studies are of comparable weight as evidence. Much
routine data are of poor quality with missing values and are plagued by
numerous biases and coding errors. RCTs on the other hand, are highly
regulated, thoroughly monitored, standardized and scrutinized. But there
is no reason to believe that all RCTs are inherently superior to, say,
prospective studies on consecutive cohorts encompassing nearly all treated
patients. While retrospective analysis could create potential statistical
issues, a priori protocols for observational studies would be a solution.
I am currently working on a Patient Registry & RCT Data Survey as part of
an ISPOR Working Group. The goal is to assess the degree to which health
plan administrators, policy makers and regulators depend on registry data
for their coverage and reimbursement decisions. Here is the link below is
to a short survey which will inform our further research:
http://tinyurl.com/2fdrkz. If you are interested in results, you are
welcome to participate.
And my questions for discussion are: Will the regulators and decision
makers start looking more closely at both RCTs and observational studies
to identify sources of best evidence in both categories? Would RCTs always
be considered superior to observational studies, regardless of their
respective quality? Are we experiencing a slow shift in paradigm? What are
the barriers to that shift?
Kind regards,
Jaro
__________________
Jaro Wex BA, MBBS, PhD (econ)
Director
Pharmarchitecture Limited
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