Understanding the differences between traditional, “explanatory” randomized controlled trials, pragmatic clinical trials, and quality improvement activities is important, because different ethical and regulatory guidelines may apply. Both randomized controlled trials and pragmatic clinical trials constitute research, defined in federal regulations as an activity intended to create generalizable knowledge (45 CFR 46). Alternatively, quality improvement activities are "data-guided activities designed to bring about immediate improvements in health care delivery in particular settings" (Lynn et al 2007).

When a pragmatic trial is intended to both improve care locally and provide generalizable knowledge, as in a learning health system, the distinction between quality improvement and research is arguably fuzzy (Faden et al 2013), especially as quality improvement techniques become more sophisticated (Finkelstein et al 2015). At its core, however, quality improvement is designed to change local processes to achieve accepted standards of care, whereas pragmatic clinical trials are designed to determine the standards themselves (Finkelstein et al 2015; Nilsen et al 2022). A given clinical trial will have elements that are more pragmatic (for example, a trial accepting all comers with limited exclusion criteria) and elements that are more explanatory (for example, a trial that lacks flexibility in how the intervention is delivered across settings) (Loudon et al 2015).

The Table below summarizes the key differences between randomized controlled trials, pragmatic trials, and quality improvement activities. We explore the continuum of pragmatism in study design in more detail in the next section.

Table. Key Differences Between Traditional Randomized Controlled Trials, Pragmatic Clinical Trials, and Quality Improvement Activities