TY - JOUR T1 - Key Principles for Conducting a Good Randomized Controlled Trial JF - Respiratory Care SP - 1211 LP - 1213 DO - 10.4187/respcare.10426 VL - 67 IS - 9 AU - Jian Luo Y1 - 2022/09/01 UR - http://rc.rcjournal.com/content/67/9/1211.abstract N2 - In this issue of Respiratory Care, Beran and colleagues1 publish a systematic review and meta-analysis on efficacies of noninvasive ventilation (NIV) and high-flow nasal cannula (HFNC) in subjects with COVID-19–induced acute hypoxemic respiratory failure. In their analysis, a total of 19 studies were included, 3 of which were randomized controlled trials (RCTs). They found no difference in risk of intubation between NIV and HFNC regardless of study design; however, discrepancies were found in mortality between non-RCTs and RCTs. There was a lower mortality when HFNC was used versus NIV from non-RCTs, whereas no difference was found between the 2 groups in RCTs. This is probably best explained by use of historical controls and selection bias, reinforcing the importance of RCTs, especially high-quality RCTs. Interestingly, 2 RCTs2,3 included in this systematic review had similar sample sizes and patient populations, which will be used as examples to discuss factors that determine quality of an RCT.The RCT is recognized as a high level of evidence in clinical research, ranking just below systematic reviews and meta-analyses in the well-known hierarchy of evidence.4 Compared to other study designs such as case reports, case-control studies, and cohort studies, an RCT has a lower risk of bias in both internal (correctness of conclusion) and external (applicability) validity.5Since the outbreak of COVID-19, more than 300,000 studies (indexed in PubMed) have been published so far, and about 2,000 studies are RCTs. In contrast to non-RCTs, the number of RCTs significantly increased during COVID-19 pandemic. This sharp increase reflects the significant contribution of RCTs to clinical practice and also the constant pursuit of better clinical evidence. However, methodological quality of some RCTs is considerably low, which eventually limits their generalizability and can even be harmful. Therefore, it is crucial … Correspondence: Jian Luo MD, Respiratory Medicine Unit, Nuffield Department of Medicine, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DU, United Kingdom. E-mail: jian.luo{at}ndm.ox.ac.uk ER -