Secular trends of incidence and prevalence of parkinsonism and subtypes: A cohort study in the United Kingdom

Background: While summarized under the umbrella term "Parkinsonism", several subtypes with different etiologies exist, including Parkinson's Disease, Vascular Parkinsonism and Drug-induced Parkinsonism. However, evidence on their incidence and prevalence remains limited. Objectives: To evaluate secular trends of incidence and prevalence of parkinsonism, Parkinson's Disease, Vascular Parkinsonism, and Drug-induced Parkinsonism from 2007 to 2021 in the United Kingdom. Methods: We used primary care data, Clinical Practice Research Datalink GOLD, from the United Kingdom. Individuals were included if they were registered from January 2007 to December 2021 with at least one year of prior observation. Incidence and prevalence were calculated on a yearly basis with 95% confidence intervals and then stratified by age and sex. Results: From 2007 to 2019, the incidence of parkinsonism and Parkinson's Disease decreased, with Parkinson's Disease incidence dropping from 35.86 (95% confidence interval: 34.22 - 37.56) to 31.40 (29.40 - 33.50) per 100,000 person-years. The prevalence of parkinsonism and Parkinson's Disease increased from 0.22% (0.22% - 0.23%) and 0.21% (0.21% - 0.22%) in 2007 to peak in 2016 with 0.25% (0.25% - 0.26%) and 0.23% (0.23% - 0.24%) respectively. The number of Vascular Parkinsonism diagnoses have increased from 2010, whereas incidence and prevalence of Drug-induced Parkinsonism remained stable. Incidence and prevalence increased with age and were generally higher in males, except for Drug-induced Parkinsonism, which was slightly higher in females. Conclusions: Given its association with aging, parkinsonism and these subtypes continue to present an increasing challenge to our aging society.