Lastly, to better contextualize externalizing in relation to prospective risk for death by suicide, we explored associations between externalizing and post-enrollment mortality. For each participant, we created a count of the past 12-month externalizing EHR codes (relative to MVP enrollment) and examined whether this count was associated with mortality via competing risk models53. We used cause of death (COD) from the ICD codes provided in the linked National Death Index (NDI) data up to December 2021 (v21, see Supplemental Table 1 for specific codes). The competing risk model allowed us to accurately estimate the hazards for specific causes of death (e.g., suicide death) in the context of competing causes (e.g., all other causes of death). We explored two competing risk models: 1) suicide-death in the context of risk for all other causes of death, and 2) “deaths of despair” (suicide, alcohol, and drug related deaths) in the context of risk for all other causes of death. We included age, gender, and race-ethnicity (non-Hispanic White, Black/African-American, Hispanic or Latino/a/x, American Indian/Alaskan Native, Asian, Native Hawaiian/Pacific Islander, multiracial, other race or ethnicity, or missing race or ethnicity) as covariates. Analyses were conducted using the survival package in R54,55.
