<p><strong>OBJECTIVE: </strong>Mental health conditions (MHCs) are prevalent among hospitalized children and could influence the success of hospital discharge. We assessed the relationship between MHCs and 30-day readmissions.</p>

<p><strong>METHODS: </strong>This retrospective, cross-sectional study of the 2013 Nationwide Readmissions Database included 512,997 hospitalizations of patients ages 3 to 21 years for the 10 medical and 10 procedure conditions with the highest number of 30-day readmissions. MHCs were identified by using the International Classification of Diseases, 9th Revision-Clinical Modification codes. We derived logistic regression models to measure the associations between MHC and 30-day, all-cause, unplanned readmissions, adjusting for demographic, clinical, and hospital characteristics.</p>

<p><strong>RESULTS: </strong>An MHC was present in 17.5% of medical and 13.1% of procedure index hospitalizations. Readmission rates were 17.0% and 6.2% for medical and procedure hospitalizations, respectively. In the multivariable analysis, compared with hospitalizations with no MHC, hospitalizations with MHCs had higher odds of readmission for medical admissions (adjusted odds ratio [AOR], 1.23; 95% confidence interval [CI], 1.19-1.26] and procedure admissions (AOR, 1.24; 95% CI, 1.15-1.33). Three types of MHCs were associated with higher odds of readmission for both medical and procedure hospitalizations: depression (medical AOR, 1.57; 95% CI, 1.49-1.66; procedure AOR, 1.39; 95% CI, 1.17-1.65), substance abuse (medical AOR, 1.24; 95% CI, 1.18-1.30; procedure AOR, 1.26; 95% CI, 1.11-1.43), and multiple MHCs (medical AOR, 1.43; 95% CI, 1.37-1.50; procedure AOR, 1.26; 95% CI, 1.11-1.44).</p>

<p><strong>CONCLUSIONS: </strong>MHCs are associated with a higher likelihood of hospital readmission in children admitted for medical conditions and procedures. Understanding the influence of MHCs on readmissions could guide strategic planning to reduce unplanned readmissions for children with cooccurring physical and mental health conditions.</p>

<p><strong>OBJECTIVE: </strong>Mental health conditions are prevalent among children hospitalized for medical conditions and surgical procedures, but little is known about their influence on hospital resource use. The objectives of this study were to examine how hospitalization characteristics vary by presence of a comorbid mental health condition and estimate the association of a comorbid mental health condition with hospital length of stay (LOS) and costs.</p>

<p><strong>METHODS: </strong>Using the 2012 Kids' Inpatient Database, we conducted a retrospective, nationally representative, cross-sectional study of 670 161 hospitalizations for 10 common medical and 10 common surgical conditions among 3- to 20-year-old patients. Associations between mental health conditions and hospital LOS were examined using adjusted generalized linear models. Costs of additional hospital days associated with mental health conditions were estimated using hospital cost-to-charge ratios.</p>

<p><strong>RESULTS: </strong>A comorbid mental health condition was present in 13.2% of hospitalizations. A comorbid mental health condition was associated with a LOS increase of 8.8% (from 2.5 to 2.7 days, P &lt; .001) for medical hospitalizations and a 16.9% increase (from 3.6 to 4.2 days, P &lt; .001) for surgical hospitalizations. For hospitalizations in this sample, comorbid mental health conditions were associated with an additional 31 729 (95% confidence interval: 29 085 to 33 492) hospital days and $90 million (95% confidence interval: $81 to $101 million) in hospital costs.</p>

<p><strong>CONCLUSIONS: </strong>Medical and surgical hospitalizations with comorbid mental health conditions were associated with longer hospital stay and higher hospital costs. Knowledge about the influence of mental health conditions on pediatric hospital utilization can inform clinical innovation and case-mix adjustment.</p>