Older adults have complex, often overlapping, medical conditions requiring careful management that may lead to increased emergency department usage compared to younger adults. Parkinson's disease (PD), a progressive neurodegenerative disorder characterized by distinct motor and nonmotor features, frequently occurs with additional comorbid disease. Classifying comorbid conditions into clinical subgroups allows for further understanding of the heterogeneity in outcomes in patients with PD. The current study examines the reasons for emergency department (ED) visits in a cohort of patients with PD and identifies comorbidities that are potential risk factors for specific ED presenting conditions.

Using data from Optum's de-identified Integrated Claims-Clinical dataset years 2010–2018, patients with PD were identified based on ICD-9/10 diagnosis codes. We identified all ED visits occurring after the first observed diagnosis code for PD. Comorbid conditions were classified using the AHRQ Clinical Classification Software (CCS). We classified patients using Latent Class Analysis (LCA) and conducted multiple logistic regression models with the outcome of reason-for-visit to examine the associations with comorbidity-profile class, patient demographics, and socio-economic characteristics.

The most common reasons for ED admission were injuries such as fractures and contusions, diseases of the circulatory system, and general signs and symptoms, including abdominal pain, malaise, and fatigue. Comorbid medical conditions often observed in this patient population include depression, diabetes mellitus, and chronic pulmonary disease. Patients in the “Poorest Health” classification of the LCA had greater odds for ED admission for diseases related to the gastrointestinal system, musculoskeletal system, and injury/poisoning categories and reduced odds for admission for diseases of the circulatory system.

Patients with PD who present to the emergency department with injuries are more likely to be in poor health overall with a high comorbidity burden. Clarifying the complex medical needs of patients with PD is the first step to further individualize care, which may reduce ED visits in this population, improve quality of life, and lessen the footprint on the healthcare system.