The Hoehn-Yahr staging is used to assess the severity of Parkinson's disease, classified into stages 0, 1, 1.5, 2, 2.5, 3, 4, and 5. According to the latest treatment guidelines for Parkinson's disease in China (2020), Hoehn-Yahr stages 1.0 to 2.5 are defined as early stage, while stages 3 to 5 are defined as mid to late-stage Parkinson's disease.