Methodological Rigour in Preclinical Urological Studies: a 14-year systematic review to increase research quality and value

Abstract Aims: Methodological rigour enhances reproducibility in preclinical studies and translation from preclinical to clinical studies. We aimed to investigate the prevalence and the trends of essential study design elements in preclinical urological studies, as well as key factors which may improve methodological rigour. Methods and Results: PubMed database was searched, and all the resulting articles in preclinical urological articles published over the past 14-years were reviewed. Total 3768 articles met inclusion criteria. Data on study design elements and animal model used were collected. Citation density and journal impact factor was also examined as a surrogate marker of study influence. We performed analysis on prevalence of seven critical study design elements, and temporal patterns over 14 years. Randomization was reported in 50.0%, blinding in 15.0%, sample size estimation in 1.0%, inclusion of both sexes in 5.7%, statistical analysis in 97.1%, housing and husbandry in 47.7%, and inclusion/exclusion criteria in 5.0%. Temporal analysis showed that the implementation of these study design elements has increased, except for inclusion of both sexes and inclusion/exclusion criteria. Reporting study design elements were not associated with increased citation density. Conclusions: The risk of bias is prevalent in 14-year publications describing preclinical urological research, and the quality of methodological rigour is poorly related to the journal impact factor or the citation of the article. Yet guidelines seem helpful in improving the research quality, because five study design elements (randomization, blinding, sample size estimation, statistical analysis, housing and husbandry) proposed by both NIH and ARRIVE guidelines have been either well reported or improved. Systematic review registration: PROSPERO CRD42022233125 One-sentence summary: Research bias still exists in the fields in preclinical urology, but it is gradually improving.