How transparent and reproducible are studies that use animal models of opioid addiction?

The reproducibility crisis in psychology has caused multiple fields to reckon with the reliability of their own findings. Many of the unfortunate aspects of research design that undermine reproducibility also threaten translation potential (Fergusson et al., 2019). In preclinical addiction research, rates of translation have been “disappointing”(Venniro et al., 2020). We examined indices of transparency and accurate and thorough reporting in animal models of opioid addiction from 2019 to 2023. By examining the prevalence of these practices, we aimed to understand whether efforts to improve reproducibility are relevant to this field. We measured the prevalence of transparency measures such as preregistration, registered reports, open data, and open code as well as compliance to the Animal Research: Reporting of In Vivo Experiments (ARRIVE) guidelines. We also measured rates of bias minimization practices (randomization, masking, and data exclusion), sample size calculations and multiple corrections adjustments. Lastly, we estimated the accuracy of test statistic reporting using statcheck. The coding of 255 articles revealed poor uptake of all transparency measures and the ARRIVE guidelines. Similarly, levels of bias minimization practices and sample size calculations were unsatisfactory. In contrast, adjustments for multiple comparisons were implemented in most articles (76.5%). Lastly, half of articles contained non-decision errors and 11% contained decision errors. Our study is the first of its kind in this field and demonstrates that attempts to improve reproducibility and, in turn, translation, are indeed needed in the animal models of opioid addiction field.