Factors influencing FDA drug approval decisions beyond clinical trial evidence: a scoping review

Introduction The Food and Drug Administration’s (FDA) approval decisions are expected to rest primarily on clinical evidence, yet concerns persist about whether political pressure, commercial interests, or institutional dynamics also influence the approval process. Methods We conducted a scoping review of empirical studies published between 1990 and 2025 evaluating factors other than clinical evidence in FDA drug approval decisions, following the PRISMA-ScR framework. Results Fifteen studies examined five categories of factors: firm-level attributes, FDA organizational structures, procedural factors, regulatory reforms, and external pressures including media attention and political salience. Most studies (10/15) evaluated these factors using speed of FDA drug approval as a primary outcome, rather than the decision to approve or reject, or a measure of decision quality. Findings were mixed, with the most consistent evidence for close agreement between advisory committee recommendations and approval decisions, identified across independent research teams. More limited evidence also suggested external stakeholder pressure may affect review times. Conclusion A paucity of empirical evidence likely points to the inherent difficulty of demonstrating influence on agency decision-making. More research is needed to evaluate the potential influence of factors beyond clinical evidence on approval decisions, and the extent to which these decisions ultimately benefit patients.