Separating presence from severity in suicidal ideation: Evidence from multilevel hurdle models

Suicidal ideation is inherently episodic, yet most analytic approaches treat it as a single continuous process, handling zero inflation as a nuisance through transformation or ill-fitting models. Such approaches may obscure distinct mechanisms governing whether ideation occurs versus how severe it becomes. We applied multilevel hurdle models to ecological momentary assessment data from a large sample of psychiatrically acute adolescents with recent suicidal thoughts (n = 244) to examine whether affective states differentially predict suicidal ideation occurrence and severity. Hurdle models decompose ideation into a binary component (presence) and a continuous component (intensity conditional on presence). Negative and positive affect were partitioned into within-person (momentary) and between-person (person-level average) components, with models examining concurrent and lagged associations while accounting for temporal persistence. Results revealed dissociable processes. Person-level average negative affect robustly predicted ideation occurrence, whereas momentary fluctuations showed weak prospective associations with presence of suicidal ideation. In contrast, both momentary and person-level average negative affect predicted greater severity once ideation was present. Positive affect showed modest concurrent associations with lower suicidal ideation presence and severity but did not reliably predict presence of prospective suicidal thinking. These findings suggest affective states, and specifically negative affect, may primarily function as amplifiers of ideation severity rather than acute triggers of ideation presence. Multilevel hurdle models offer a useful framework for capturing the episodic structure of suicidal ideation and informing real-time prevention efforts. (PsycInfo Database Record (c) 2026 APA, all rights reserved).