# Influence of psychiatric comorbidity on in-hospital costs for multitrauma patients

## TL;DR

This study found that psychiatric comorbidity in multitrauma patients is linked to higher hospital costs, but these costs are mainly due to longer stays and more surgeries, not the psychiatric condition itself.

## Contribution

The study introduces a novel classification of psychiatric comorbidity subtypes and identifies key factors driving increased in-hospital costs in multitrauma patients.

## Key findings

- Patients with psychiatric comorbidity had significantly higher median in-hospital costs (€22,000) compared to controls (€15,200).
- The 'Acute' psychiatric subgroup had the highest median costs (€47,000).
- Psychiatric comorbidity was not an independent predictor of increased costs; instead, hospital stay duration, ISS, and surgical interventions were significant predictors.

## Abstract

The purpose of this study was to quantify the impact of psychiatric comorbidity on in-hospital costs after multitrauma.

A retrospective single-center cohort study identified adult trauma patients with an Injury Severity Score (ISS) ≥ 16, who entered the hospital between January 2018 and December 2019. Descriptive statistics were assessed for patient characteristics, injury characteristics, and injury outcomes. Bivariate analysis was performed for in-hospital costs between patients with and without psychiatric comorbidity. The psychiatric cohort was then further divided into different sub-cohorts by status of their psychiatric comorbidity: ‘Acute’ for patients with no known history of psychiatric illness who required inpatient psychiatric consultation for a newly diagnosed or suspected psychiatric illness, ‘Stable’ for patients with a prior psychiatric history that did not require inpatient psychiatric consultation, and ‘Chronic’ for patients with a prior psychiatric history that required continued inpatient psychiatric consultation. Baseline demographic and in-hospital cost data was compared between these cohorts.

Of the 616 patients meeting inclusion criteria, 94 patients (15.3%) either suffered from pre-existing psychiatric illness, needed psychiatric consultation during hospitalization, or suffered both pre-existent from a psychiatric illness and needed psychiatric consultation during hospitalization. The psychiatric cohort generated significantly higher total in-hospital costs than the control cohort (median costs: €22.000 versus €15.200, respectively (p < 0.01). In particular, the Acute psychiatric cohort generated the highest hospital expenses (median total in-hospital costs €47.000). Multivariable regression analyses did not reveal psychiatric comorbidity as an independent predictor of higher in-hospital costs (p = 0.88). Instead, the duration of hospital stay (p < 0.01), ISS (p < 0.01), and the number of total surgical interventions (p < 0.01) independently predicted higher total in-hospital costs.

Although in-hospital costs of multitrauma patients were higher among patients with psychiatric comorbidity, psychiatric comorbidity does not independently predict increased in-hospital costs for patients after multitrauma. Instead, higher in-hospital costs are due to longer inpatient stay, higher ISS and greater number of surgical interventions among those with psychiatric comorbidity.

The online version contains supplementary material available at 10.1007/s00068-025-02868-w.