Objectives: According to the ideation-to-action framework of suicidality, suicidal ideation and suicidal action arise via distinct trajectories. Studying suicidality under this framework requires accurate identification of both ideation and action. We sought to assess the accuracy of ICD-10 codes for suicidal ideation and action in emergency department (ED) encounters. Methods: Accuracy of ICD-10 coding for suicidality was assessed through chart review of clinical notes for 205 ED encounters among patients 6-18 years old at a large academic pediatric hospital between June 1, 2016, and June 1, 2022. Physician notes were reviewed for documentation of past or present suicidal ideation, suicidal action, or both. The study cohort consisted of 103 randomly selected "cases," or encounters assigned at least one ICD-10 code for suicidality, and 102 propensity-matched "non-cases" lacking ICD-10 codes. Accuracy of ICD-10 codes was assessed using sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Results: Against a gold standard chart review, the PPV for ICD-10 suicidality codes was 86.9%, and the NPV was 76.2%. Nearly half of encounters involving suicidality were not captured by ICD-10 coding (sensitivity=53.4%). Sensitivity was higher for ideation-present (82.4%) than for action-present (33.7%) or action-past (20.4%). Conclusions: Many cases of suicidality may be missed by relying on only ICD-10 codes. Accuracy of ICD-10 codes is high for suicidal ideation but low for action. To scale the ideation-to-action model for use in large populations, better data sources are needed to identify cases of suicidal action.

The authors have declared no competing interest.

This study was supported by the Centers for Disease Control and Prevention (CDC) of the U.S. Department of Health and Human Services (HHS) as part of a financial assistance award. The contents are those of the authors and do not represent the official views of, or an endorsement by, CDC, HHS, or the U.S. government. Support was provided by the National Center for Advancing Translational Sciences, National Institutes of Health Cooperative Agreement (U01TR002623).

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The Institutional Review Board of Boston Children's Hospital waived ethical approval for this work (IRB-P00043211).

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

Yes

I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

Yes

All data produced in the present work are contained in the manuscript