Importance: Making rational decisions about screening requires information about its harms, but high-quality evidence is often either not available or not used. One reason may be that we lack a coherent framework, a taxonomy, for conceptualizing and studying these harms.
Objective: To create a taxonomy, we categorized harms from several sources: systematic reviews of screening, other published literature, and informal discussions with clinicians and patients. We used this information to develop an initial taxonomy and vetted it with local and national experts, making revisions as needed.
Results: We propose a taxonomy with 4 domains of harm from screening: physical effects, psychological effects, financial strain, and opportunity costs. Harms can occur at any step of the screening cascade. We provide definitions for each harm domain and illustrate the taxonomy using the example of screening for lung cancer.
Conclusions and relevance: The taxonomy provides a systematic way to conceptualize harms as experienced by patients. As shown in the lung cancer screening example, the taxonomy also makes clear where (which domains of harms and which parts of the screening cascade) we have useful information and where there are gaps in our knowledge. The taxonomy needs further testing and validation across a broad range of screening programs. We hope that further development of this taxonomy can improve our thinking about the harms of screening, thus informing our research, policy making, and decision making with patients about the wisdom of screening.