Burden of mental illness on hospital and patient outcomes among asthma hospitalizations.

OBJECTIVE: Empirical evidence demonstrates the comorbidity of asthma and mental illness, though limited studies have evaluated the patient and hospital outcomes associated with such conditions. As such, this study evaluated the burden of this comorbidity on health resource utilization and patient disposition among asthma hospitalizations. METHODS: A secondary analysis of the Nationwide Inpatient Sample (2009-2011) was conducted, with study population of asthma hospitalizations limited to those 18 years of age and older. International Classification of Disease, 9th Revision, Clinical Modification codes were utilized to identify asthma and mental illness discharges. Length of stay was defined as number of days stayed in the hospital, total charges were inflation-adjusted, and patient disposition was defined as routine versus not routine. All analyses were survey-weighted and adjusted for patient and hospital characteristics. RESULTS: Approximately 29% of the asthma hospitalizations reported mental illness. Any mental illness was associated with increased length of stay in the hospital (10% increase), total costs (11% increase), and lower odds of routine disposition (21% decrease). Substance-related disorder also increased length of stay in the hospital (4% increase), costs (9% increase), and lower odds of routine disposition (29% decrease). Age-stratified analyses further demonstrated similar trends among most age groups. CONCLUSION: The results of this study complement the extant literature by demonstrating the burden of the asthma-mental health nexus on health resource utilization and patient outcomes. The increased length of stay, cost, and decreased likelihood of routine disposition associated with mental illness highlight the need for integrated care to address mental illness as part of routine care.