How Socioeconomic Status Influences Mortality Risk in Patients With Parkinson Disease

November 6, 2020
Matthew Gavidia

Individual-level low socioeconomic status (SES) was found to be significantly associated with increased mortality in Korean patients with Parkinson disease, whereas regional-level SES was not.

Individual -evel low socioeconomic status (SES) was found to be significantly associated with increased mortality in Korean patients with Parkinson disease (PD), according to study findings published in Parkinsonism & Related Disorders.

After Alzheimer disease, PD serves as the second most prevalent neurodegenerative disorder, with an incidence rate rising faster than any other neurodegenerative condition. Moreover, the significant cost associated with PD has been addressed in prior studies, with 1 analysis finding that for each patient, the annual direct cost for care totaled $12,800, and the indirect cost, such as early retirement, an additional $10,000.

Although the high-cost nature of PD is known, the researchers highlight that very few studies have investigated the role of SES in relation to mortality in PD, which has been shown to be associated with increased mortality in the general population.

Seeking to evaluate the 10-year mortality rate and impact of SES on mortality in PD, the researchers derived data from the Korean National Health Insurance Service (NHIS)–National Sample Cohort, on patients with PD diagnosed between 2004 and 2015. They examined the impact of both individual-level SES, such as insurance type or income level, and regional-level SES, such as residential area, on mortality in PD.

In the study, 26,570 patients with PD were enrolled from the data source and matched with a control cohort of 23,913. Each participant was placed into income deciles based on whether they qualified for medical aid (single-family household income  ≤ $600 or less per month) or national health insurance, which was categorized into 4 categories:

  • Lowest: all medical aid enrollees + 0 to 20th percentile of NHIS enrollees
  • Low-middle: 21st to 50th percentile of NHIS enrollees
  • Middle-high: 51st to 80th percentile of NHIS enrollees
  • Highest: 81st to 100th percentile of NHIS enrollees

Cox proportional hazard models were utilized to identify effects of SES on mortality via HRs and 95% CIs.

After a 10-year follow-up, the mortality rate was found to be higher in the PD group (30.37%) than the control group (16.69%). When stratifying for income, patients with PD in the low-middle group were found to exhibit significantly decreased HRs of 0.704 (95% CI, 0.533-0.930) compared with to those in the lowest group, signaling a higher risk of mortality among those with lower SES.

Aligned with this perceived higher risk among the lowest group, the medical aid group additionally showed an increased mortality rate (HR, 1.552; 95% CI, 1.191–2.021) compared with the NHI group. In subgroup analyses, researchers found that medical aid was associated with mortality, only in female patients with PD (HR, 1.740; 95% CI, 1.242-2.438) or those aged 60 to 79 years (HR, 1.434; 95% CI, 1.005-2.045).

While individual-level low SES was significantly associated with increased mortality, regional-level SES was not related with mortality in PD..

“The results of this study should raise awareness in clinicians and health care professionals about the unfavorable prognosis in patients with PD with low SES,” conclude the researchers. “Further studies with more detailed information about SES and that consider PD severity must be conducted.”

Reference

Yoon SY, Shin J, Chang JS, Lee SC, Kim YW. Effects of socioeconomic status on mortality after Parkinson's disease: a nationwide population-based matched cohort study in Korean populations. Parkinsonism Relat Disord. Published online October 27, 2020. doi:10.1016/j.parkreldis.2020.10.017