How and Under What Conditions Do Patient Portals Improve Cancer Screening Completion: A Scoping Review.

Introduction: Studies have shown that patient portals facilitate cancer screening, but less is known about how. Causal pathway diagrams, which include influencing factors such as mechanisms and moderators, can be used to understand how portals improve screening. The authors conducted a scoping review of influencing factors to inform early causal pathway diagrams of the portal as a strategy to increase cancer screening. Methods: The authors searched PubMed for U.S. studies published from 2014 to 2024, including average-risk patients; portal interventions/evaluations; and primary outcomes of breast, cervical, colorectal, or lung cancer screening. Two authors completed manuscript screening and data extraction and synthesized findings to create causal pathway diagrams. Results: Thirty-two studies met inclusion criteria. Studies were often set in large academic health systems (n=13) or utilized survey data from nationally representative cohorts (n=11); 6 were RCTs. Most studies focused on breast (n=10) or colorectal (n=9) cancer screening. Of 21 studies comparing portal use with no use, 18 found that portals were associated with increased screening. Most proposed influencing factors were hypothetical, citing findings from prior literature rather than observed directly. Of the 10 studies that performed statistical analysis, significant moderators included provider recommendation for self-scheduling; significant mechanisms included cancer worry and patient activation for general portal use, cancer fatalism and patient activation for secure messaging with providers, and choice architecture for interventions delivered through secure messaging. Discussion: Few studies directly tested influencing factors, suggesting a significant research gap. More research is needed to further evaluate proposed mechanisms to understand how portals facilitate cancer screening and optimize implementation. Registration: The protocol for this scoping review was registered through Open Science Framework.