Association Between Comorbid Psychiatric Disorders and Hospital Resource Use in Physically Ill Pediatric Inpatients: A Case-Matched Analysis

Objective: To understand differences in hospital length of stay and costs associated with the presence of a comorbid psychiatric disorder among physically ill inpatients within a publicly funded pediatric hospital.

Method: This was a retrospective observational design using administrative data on physically ill inpatients 2 to 18 years old who were admitted over a 5-year period (n = 54,316 admissions). Records with (n = 4,953) and without (n = 49,363) documented comorbid psychiatric disorder were compared for differences in baseline characteristics. To optimize the balance of measured covariates, individuals with comorbid psychiatric disorders were matched on propensity score, case mix group, and Elixhauser comorbidities, resulting in 4,371 pairs of inpatients with and without a comorbid psychiatric disorder. Differences in length of stay and total hospital costs were assessed using generalized estimating equation models on matched patients.

Results: Unmatched analyses demonstrated that inpatient admissions with comorbid psychiatric disorders were associated with higher occurrence of previous hospitalizations (69.2% versus 55.0%), unscheduled admissions (66.9% versus 60.9%), medical admissions (75.6% versus 52.7%), urgent admissions (62.5% versus 56.2%), and Elixhauser comorbidities (69.0% versus 39.0%), with standardized differences > |0.1|. Matched analyses demonstrated a 9.6% longer length of stay (95% CI = 5.7-13.7; p < .001) and 9.6% higher costs per admission (95% CI = 5.9-13.4; p < .001) in inpatients with comorbid psychiatric disorders compared to those without.

Conclusion: The complexity of inpatients with a comorbid psychiatric disorder, in conjunction with the approximate 10% increase in hospital resource use, highlights the need for innovative models of clinical care and research directed at improving patient outcomes and reducing hospital costs.