Exploratory analyses in aetiologic research and considerations for assessment of credibility: mini-review of literature

OBJECTIVE To provide considerations for reporting and interpretation that can improve assessment of the credibility of exploratory analyses in aetiologic research. DESIGN Mini-review of the literature and account of exploratory research principles. SETTING This study focuses on a particular type of causal research, namely aetiologic studies, which investigate the causal effect of one or multiple risk factors on a particular health outcome or disease. The mini review included aetiologic research articles published in four epidemiology journals in the first issue of 2021: American Journal of Epidemiology, Epidemiology, European Journal of Epidemiology, and International Journal of Epidemiology, specifically focusing on observational studies of causal risk factors of diseases. MAIN OUTCOME MEASURES Number of exposure-outcome associations reported, grouped by type of analysis (main, sensitivity, and additional). RESULTS The journal articles reported many exposure-outcome associations: a mean number of 33 (range 1-120) exposure-outcome associations for the primary analysis, 30 (0-336) for sensitivity analyses, and 163 (0-1467) for additional analyses. Six considerations were discussed that are important in assessing the credibility of exploratory analyses: research problem, protocol, statistical criteria, interpretation of findings, completeness of reporting, and effect of exploratory findings on future causal research. CONCLUSIONS Based on this mini-review, exploratory analyses in aetiologic research were not always reported properly. Six considerations for reporting of exploratory analyses in aetiologic research were provided to stimulate a discussion about their preferred handling and reporting. Researchers should take responsibility for the results of exploratory analyses by clearly reporting their exploratory nature and specifying which findings should be investigated in future research and how.