Talk:Pragmatic clinical trial

The section discussing the continuum from explanatory to pragmatic trial designs could be improved by updating the references to mention the development of the original PRECIS too and subsequent revision to PRECIS-2. I have put some suggested text in BOLD below:

"Distinction from other forms of trials The distinction between pragmatic and explanatory trials is not the same as the distinction between randomized and nonrandomized trials. Any trial can be either randomized or nonrandomized and have any degree of pragmatic and explanatory power, depending on its study design, with randomization being preferable if practicably available. Work over the last decade has sought to formalise the design features upon which trials are more or less pragmatic. This includes the initial PRagmatic-Explanatory Continuum Indicator Summary (PRECIS) developed by Thorpe and colleagues . PRECIS included 10 domains with a visual scale to represent where the trial fell on each domain . PRECIS was later revised to PRECIS-2, which contains 9 domains each provided a 5 point likert-scale upon which a trial can be scored from very explanatory (1) to very pragmatic (5)  However, most randomized controlled trials (RCTs) to date have leaned toward the explanatory side of the pragmatic-explanatory spectrum, largely because of the value traditionally placed on proving causation by deconfounding as part of proving efficacy, but sometimes also because "attempts to minimize cost and maximize efficiency have led to smaller sample sizes".[2] The movement toward supporting pragmatic randomized controlled trials (pRCTs) hopes to make sure that money spent on RCTs is well spent by providing information that actually matters to real-world outcomes,[2] regardless of conclusively tying causation to particular variables. This is the pragmatic element of such designs. Thus pRCTs are important to comparative effectiveness research,[2] and a distinction is often (although not always) made between efficacy and effectiveness, whereby efficacy implies causation proved by deconfounding other variables (we know with certainty that drug X treats disease Y by mechanism of action Z) but effectiveness implies correlation with outcomes regardless of presence of other variables (we know with certainty that people in a situation similar to X who take drug A tend to have slightly better outcomes than those who take drug B, and even if we think we may suspect why, the causation is not as important)."

A table could also be inserted showing the PRECIS-2 domains

Adapted from Loudon K, Treweek S, Sullivan F, Donnan P, Thorpe KE, Zwarenstein M. The PRECIS-2 tool: designing trials that are fit for purpose. BMJ. 2015;350:h2147 and

SNicholls1979 (talk) 18:47, 22 February 2019 (UTC)Stuart G. Nicholls