Impact of Depression on Hospitalization and Related Outcomes for Parkinson's Disease Patients: A Nationwide Inpatient Sample-Based Retrospective Study

Background Major Depressive Disorder (MDD) is a common comorbidity that significantly affects the quality of life and disease outcomes in Parkinson's disease (PD) patients. No studies have been conducted to our knowledge to address the health care utilization and its outcomes in these patients. The aim of this study is to analyze and discern the differences in the hospitalization outcomes, comorbid conditions, and utilization of procedures in PD patients versus patients with comorbid MDD. Methods We used the Nationwide Inpatient Sample from the Healthcare Cost and Utilization Project from year's 2010-2014. We identified PD and MDD as a primary and secondary diagnosis respectively using validated International Classification of Diseases, 9th Revision, and Clinical Modification codes. Pearson's chi-square test and independent sample T-test were used for categorical data and continuous data, respectively. All statistical analysis was done by SPSS 22.0 in this study. Results Extensive analysis was performed on 63,912 patients with PD and 1445 patients with PD having MDD. Patients with comorbid depression had three times greater chances of disposition to acute care hospital (3.1% vs. 1.1%, p < 0.001). Median length of hospitalization was higher in Parkinson's patients with depression (5.85 vs. 4.08 days; p < 0.001) though the median cost of hospitalization was low ($ 31,039 vs. $ 39,464; p < 0.001). This could be because therapeutic procedures performed during the hospitalization were lower in Parkinson's patients with depression (0.53 vs. 0.89, p < 0.001). Utilization of Deep Brain Stimulation (DBS) was lower in Parkinson's patients with depression (9.4% vs. 25.6%, p < 0.001). In--hospital mortality was significantly higher in Parkinson's patients with depression (1.4% vs. 1.1%; p < 0.001). Conclusion Our study establishes the negative impact of depression in PD with regards to hospitalization-related outcomes including the illness severity, comorbid conditions, risk of mortality, utilization of diagnostic and therapeutic procedures, the length of stay and disposition as compared to PD without depression.