Comorbid Psychosis Associated With More Severe Parkinson Disease, Longer Hospital Stays

Findings of a retrospective study show that comorbid psychosis and depression in patients with Parkinson disease are associated with greater disease severity and higher healthcare utilization.

Findings of a retrospective study show that comorbid psychosis and depression in patients with Parkinson disease (PD) are associated with greater disease severity and higher healthcare utilization.

Longer duration of illness with PD is a known risk factor for developing both depression and psychosis, and previous studies have found that psychiatric comorbidities are linked to poorer health-related quality of life and higher treatment costs. The physiological mechanism explaining the relationship between PD and psychiatric comorbidities is not yet known.

A recent study published in Cureus aimed to evaluate differences in hospital outcomes among patients with PD by the presence of depression and psychosis and the impact of these comorbidities on severity of illness and hospital discharges. Investigators used nationwide inpatient sample data from 2010 to 2014 to identify patients 40 years or older with a principal diagnosis of PD (N = 62,783).

Diagnosis codes were also used to identify secondary diagnoses of depression or psychosis, leading to the creation of 3 groups: comorbid depression (n = 11,358), comorbid psychosis (n = 2475), and no depression/psychosis (n = 48,950). Researchers also included patients’ demographic information (age, sex, race, median household income), severity of illness (measured by loss of function), length of stay (measured by nights in hospital), total admission charges, and utilization of deep brain stimulation (DBS).

In analyzing the demographic information, researchers found that the rate of PD with depression was higher in white patients, whereas PD with psychosis was higher in black patients. Women made up 37.2% of the total inpatient sample but accounted for 44.9% and 41.8% of depression and psychosis diagnoses, respectively. Also, the proportion of patients with income below the 25th percentile was higher in the group with psychosis than in the group with depression and all patients (28.6% vs 21.9% and 22.4%, respectively).

Patients with comorbid psychosis were significantly more likely to have moderate or major severity of illness than those in the other groups. However, they were much less likely to use DBS than those with depression or the total sample (3.9% vs 24.3% and 26.1%, respectively; P <.001).

Using a logistic regression model to control for demographic confounding variables, the researchers found a 1.4-fold higher association (95% CI, 1.252-1.524) between major severity of illness and comorbid psychosis in inpatients with PD.

Additionally, patients with psychosis had a longer mean (SD) length of stay (7.3 [15.3] days) than did patients with depression (4.2 [9.8] days) or the total sample (4.1 [8.7] days) (P <.001). Surprisingly, however, they had significantly lower mean charges compared with the comorbid depression group or the total sample ($31,240 vs $38,581 and $39,688, respectively).

Based on the high prevalence of comorbid depression and psychosis in patients with PD and the observed associations between the comorbidities and disease severity and healthcare resource use, the study authors suggested that healthcare providers should actively screen patients with PD for psychiatric comorbidities.

“Psychiatric comorbidities in PD should be considered an integral part of the disease, and a multidisciplinary approach to managing this disease is crucial to improve the overall outcome and the health-related quality of life of PD patients,” they concluded.


Imran S, Patel RS, Onyeaka HK, et al. Comorbid depression and psychosis in Parkinson’s disease: a report of 62,783 hospitalizations in the United States. Cureus. 2019;11(7):e5227. doi: 10.7759/cureus.5227.

Related Videos
Nicki Niemann, MD, neurologist at the Muhammad Ali Parkinson Center.
Michael S. Fitts, The University of Alabama at Birmingham,
Michael Fitts, Michael J. Fox Foundation
Related Content
CH LogoCenter for Biosimilars Logo