The direct and interactive effects of physical abuse severity and negative affectivity on length of psychiatric hospitalization: evidence of differential reactivity to adverse environments in psychiatrically high-risk youth.

The current study examined the interactive influence of multiple factors (i.e., physical abuse severity and negative affectivity) in predicting youth's inpatient psychiatric length of stay (LOS), extending previous research focused on identification of only single LOS predictors. Elevated physical abuse severity was hypothesized to predict longer youth LOS, and negative affectivity was anticipated to exacerbate this relationship. This study included 42 youth. Clinicians rated youth temperament, whereas physical abuse severity and LOS were coded from youth medical records. Controlling for other previously determined predictors of LOS (i.e., age, gender, and GAF), moderation analyses confirmed hypotheses, revealing a temperament by environment interaction. Specifically, physical abuse severity was positively associated with LOS only in the context of high negative affectivity. Findings highlighted the importance of disentangling the interactive effects of multiple factors in predicting LOS. Moreover, critical clinical implications involving prioritized trauma assessment and treatment for inpatient youth are discussed.