The value of pragmatic and observational studies in health care and public health.

Evidence-based practice is an important component of health care service delivery. However, there is a tendency, embodied in tools such as Grades of Recommendation, Assessment, Development, and Evaluation, to focus principally on the classification of study design, at the expense of a detailed assessment of the strengths and limitations of the individual study. Randomized controlled trials (RCTs), and in particular the classical "explanatory" RCT, have a privileged place in the hierarchy of evidence. However, classical RCTs have substantial limitations, most notably a lack of generalizability, which limit their direct applicability to clinical practice implementation. Pragmatic and observational studies can provide an invaluable perspective into real-world applicability. This evidence could be used more widely to complement ideal-condition results from classical RCTs, following the principle of triangulation. In this review article, we discuss several types of pragmatic and observational studies that could be used in this capacity. We discuss their particular strengths and how their limitations may be overcome and provide real-life examples by means of illustration.