In 2020, California launched ACEs Aware, an initiative for clinicians to identify and address Adverse Childhood Experiences (ACEs) and risk of toxic stress in health care settings. A key tool is an algorithm guiding risk stratification and clinical response. This report describes an effort to update the algorithm via an expert committee and usability testing and the final algorithm that resulted from this process.

Updating California’s Adverse Childhood Experiences (ACEs) and Toxic Stress Risk Assessment and Response Algorithm

Nicole K. Eberhart, Edward L. Machtinger, Ingrid Estrada-Darley, Suzanne Perry, Priya Gandhi, Alejandro Roa Contreras, Ryan K. McBain, Nadine Burke Harris

ResearchPublished Jun 2, 2026

Adverse Childhood Experiences (ACEs) and toxic stress are major, costly public health issues facing California that significantly impact the health and well-being of children, adults, and families. In 2020, California launched ACEs Aware, a first-in-the-nation initiative for clinicians to identify and address ACEs and the risk of toxic stress in patients in health care settings. ACEs Aware recommends key tools for screening for and responding to ACEs and risk of toxic stress, including an algorithm that provides guidance for clinicians to determine a patient’s risk of toxic stress physiology and an appropriate corresponding clinical response. California state legislation requires that ACEs Aware tools and protocols, such as the algorithm, be updated every five years to ensure that they incorporate the latest science and clinical experience. In this report, the authors describe the process for updating the original algorithm and provide a new algorithm for use by clinicians in California and nationwide.

The process of updating the algorithm involved two stages: (1) input from a committee of national experts in ACEs, toxic stress, and trauma-informed health care and (2) usability testing, including cognitive interviews with clinicians and a usability experiment in which clinicians applied the algorithm to patient vignettes.

Key Takeaways

  • Through review and discussion of the latest research on preventing and treating toxic stress physiology, the algorithm advisory committee recommended that the updated algorithm highlight trauma-informed health care, protective factors, and other adversities beyond the original ten ACEs in assessing risk of toxic stress physiology.
  • Cognitive interviews revealed that most clinicians perceived the updated algorithm to be clear and self-explanatory. They were appreciative of newly included content that prompted them to promote protective factors and consider other drivers of risk of toxic stress physiology during risk assessment. Interviewees provided insights on minor clarifications that would be helpful.
  • An experiment in which clinicians applied the algorithm to patient vignettes revealed that most clinicians accurately assessed toxic stress risk (85 percent or higher) and selected the recommended clinical response (86 percent or higher)—even without training. Clinicians’ accuracy was lowest when clinical suspicion of toxic stress physiology was applicable, suggesting a need for additional training for more complex cases.
  • In sum, input from a committee of ten national experts and usability testing with 97 California clinicians resulted in an updated ACEs and Toxic Stress Risk Assessment and Response Algorithm suitable for use by clinicians in California and nationwide.

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Eberhart, Nicole K., Edward L. Machtinger, Ingrid Estrada-Darley, Suzanne Perry, Priya Gandhi, Alejandro Roa Contreras, Ryan K. McBain, and Nadine Burke Harris, Updating California’s Adverse Childhood Experiences (ACEs) and Toxic Stress Risk Assessment and Response Algorithm. Santa Monica, CA: RAND Corporation, 2026. https://www.rand.org/pubs/research_reports/RRA4408-1.html.
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This research was funded by the UCLA/UCSF ACEs Aware Family Resilience Network and conducted in the Health Services and Outcomes Program of RAND Health.

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