Epidemiology of inpatient stay in Parkinson’s disease in the United States: Insights from the Nationwide Inpatient Sample

• Our study uses data from the largest publicly available all-payer inpatient care database in the United States.
• A total of 3,015,645 admissions of Parkinson’s disease (PD) patients were documented from 2002–2011, with 3.9% resulting in inpatient mortality.
• Pneumonia was the most common cause of admission in PD patients, followed by urinary tract infection (UTI) and sepsis.
• In PD patients, the incidence of UTI and sepsis is increasing, while for other comorbidities, it is decreasing.
• The inflation-adjusted cost of care has been steadily rising from $22,250 per hospitalization in 2002 to $37,942 in 2011.

The total number of people living with Parkinson’s disease (PD) worldwide is expected to double by 2030. The risk factors for emergency department visits in PD patients have been described before, however, there is limited data on inpatient hospitalizations of PD patients. We derived our study cohort from the Nationwide Inpatient Sample (NIS) database from 2002–2011. The NIS is a stratified 20% sample of discharges from all U.S. hospitals. We extracted causes of hospitalization using International Classification of Diseases, 9th revision, Clinical Modification (ICD-9-CM) codes and calculated inpatient mortality, length of stay and cost. Further, the significance of trends over 10 years was assessed. A total of 3,015,645 (weighted) admissions of PD patients were documented from 2002–2011. Pneumonia, urinary tract infection (UTI), septicemia and aspiration pneumonitis were the most common causes of admission, of which incidence of sepsis and UTI was trending up. Of all causes, 3.9% of the admissions resulted in inpatient mortality. Inpatient mortality for PD patients decreased from 4.9% in 2002 to 3.3% in 2011 (p < 0.001). The median length of stay has also steadily declined from 3.6 days in 2002 to 2.3 days in 2011. However, the inflation-adjusted cost of care has been steadily rising, from $22,250 per hospitalization in 2002 to $37,942 in 2011. We conclude that the epidemiology of inpatient admissions in PD has changed significantly over the last decade. Our study underscores the need for future, in-depth prospective studies to explore this changing disease spectrum to design preventive measures and targeted interventions.