Context: Considering the substantial increase in research funding in the field of urology, minimizing research waste should be a top priority. Systematic reviews (SRs) compile available evidence regarding a clinical question into a single critical resource. If properly utilized, SRs can help minimize redundant studies, focus attention to unsubstantiated treatments, and reduce research waste.

Objectives: To appraise the use of SRs as justification for conducting randomized controlled trials (RCTs) published in high impact urology journals, and to report the ways SRs were incorporated into RCT manuscripts published in the top four urology journals by h5 index.

Methods: On December 13, 2019, a PubMed search was conducted for RCTs published in the top four urology journals according to the Google Scholar h5-index: European Urology, BJU International, The Journal of Urology, and Urology. For an article to be eligible for inclusion in this study, it must have been a full length RCT, published between November 30, 2014, and November 30, 2019 in one of the identified journals, reported only human subjects, and been accessible in English. The following data points were extracted independently by select investigators from each included RCT: manuscript title, year of publication, journal title, type of intervention (drug, medical device, procedure, other), funding source (government, hospital/university, industry, mixed) type of trial (parallel groups, crossover, cluster), and total number of participants reported in each RCT. The included RCTs were searched for reference to an SR, which was then recorded as "yes - verbatim," "yes - inferred," or "not used as justification" and the location in the manuscript where the SR was cited was recorded.

Results: Of the 566 articles retrieved, 276 were included. Overall, 150 (54.3%) RCTs cited an SR as either verbatim (108; 39.1%) or inferred (42; 15.2%) trial justification, while 126 (45.7%) did not use an SR for RCT justification. Of those 126, 107 (84.9%) RCTs did not cite an SR to any extent. A significant association was noted between verbatim justification and type of intervention (x²=20.23, p=0.017), with 18 of 31 (58.1%) "other" interventions (i.e. psychosocial intervention, exercise programs, and online therapy) having an SR cited as verbatim justification. Only 39 of 118 (33.1%) pharmaceutical trials referenced an SR as verbatim justification. Of 403 systematic review citations, 205 (50.8%) appeared in the Discussion section, while 15 (3.7%) were in the Methods section.

Conclusions: We found that RCTs published in four high impact urology journals inconsistently referenced an SR as justification and 39.1% of our entire sample did not reference an SR at all. These findings indicate that a divide exists between the instruction and implementation of evidence based medicine in the field of urology concerning RCTs published in the top four journals. Educating clinicians and researchers on the use of SR as justification for RCTs in urology may reduce research waste and increase the quality of RCTs in the field.