Methodological rigour in preclinical urology: a systematic review reporting research quality over a 14-year period

Objective: To investigate the prevalence and trends of essential study design elements in preclinical urological studies, as well as key factors that may improve methodological rigour, as the demand for methodological rigour in preclinical studies is increasing since research reproducibility and transparency in the medico-scientific field are being questioned. Methods and Results: PubMed was searched to include preclinical urological studies published between July 2007 to June 2021. A total of 3768 articles met the inclusion criteria. Data on study design elements and animal models used were collected. Citation density was also examined as a surrogate marker of study influence. We performed an analysis of the prevalence of seven critical study design elements and temporal patterns over 14 years. Randomisation was reported in 50.0%, blinding in 15.0%, sample size estimation in 1.0%, inclusion of both sexes in 6.3%, 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 associated with increased citation density in randomisation and statistical analysis. Conclusions: The risk of bias is prevalent in 14-year publications describing preclinical urological research, and the quality of methodological rigour is barely related to the citation density of the article. Yet five study design elements (randomisation, blinding, sample size estimation, statistical analysis, and housing and husbandry) proposed by both the National Institutes of Health and Animal Research: Reporting of In Vivo Experiments guidelines have been either well reported or are being well reported over time. Systematic Review Registration: PROSPERO CRD42022233125.