Randomized controlled trials in nephrology: state of the evidence and critiquing the evidence.

The randomized controlled trial (RCT) remains the "gold standard" for the evaluation of therapies. Despite some progress during the past decade, the number and quality of published RCTs addressing the core issues for patients with CKD and with renal diseases, in general, lag behind other areas in internal medicine. The paucity of robust evidence results in fewer patients receiving evidence-based therapies in nephrology and fewer rigorous systematic reviews to inform nephrology practice and health care policy. Because trials of lower methodologic rigor continue to be published, the evidence-based practitioner must evaluate new evidence from the medical literature carefully before incorporating that evidence into their clinical practice. The types of errors that may limit the validity or applicability of evidence from RCTs is outlined. A detailed discussion of the most important design elements for the conduct of a high-quality RCT is described in the text. These considerations are placed into the context of critical appraisal tools. These tools allow the clinician to efficiently assess the quality of published RCTs and to determine how the new RCT evidence should change current best practice.