Objective:

We sought to analyze demographic and survival differences of Parkinson's disease (PD) cases first diagnosed in inpatient settings compared to ambulatory settings.

Background:

Medical claims data in research is increasingly being used to study neurodegenerative diseases, like Parkinson’s disease, due to the availability of large population-based datasets. The high cost of these data force some investigators to purchase limited datasets, especially only inpatient samples, resulting in potential biases. We sought to examine demographic differences in cases first diagnosed in inpatient files compared to those first diagnosed in ambulatory settings.

Design/Methods:

We identified all incident PD cases (ICD-10 G20) from 2016-2018 using Medicare data from 2014-2019 and classified cases as inpatient cases if their first PD diagnosis was from an inpatient claims file and ambulatory cases if the first PD diagnosis was from ambulatory files. We calculated the odds ratio (OR) and 95% confidence interval (CI) for demographic characteristics between inpatient and ambulatory PD cases using binary logistic regression. We used Cox proportional hazards to calculate survival hazard ratios (HR) and 95% CI between inpatient and ambulatory PD cases from diagnosis through end of 2019. 

Results:

We identified 286,589 total incident PD cases from 2016-2018. There were 48,052 (16.8%) inpatient PD cases and 238,537 (83.2%) ambulatory cases. Inpatient PD cases were more likely to be older (OR=1.029, 95% CI 1.027-1.030), male (OR=1.08, 95% CI 1.06-1.10), black (OR=1.37, 95% CI 1.32-1.43), Hispanic (OR=1.12, 95% CI 1.07-1.17), Native American (OR=1.38, 95% CI 1.18-1.61), smokers (OR=1.18, 95% CI 1.15-1.21) and reside in more deprived areas (OR=1.35, 95% CI 1.32-1.38). Inpatient PD cases were also at a higher risk of death compared to ambulatory PD cases (HR=1.91, 95% CI 1.88-1.94) following initial diagnosis date.

Conclusions: