Projections for prevalence of Parkinson's disease and its driving factors in 195 countries and territories to 2050: modelling study of Global Burden of Disease Study 2021

Abstract

Objective: To predict the global, regional, and national prevalence of Parkinson's disease by age, sex, year, and Socio-demographic Index to 2050 and quantify the factors driving changes in Parkinson's disease cases.

Design: Modelling study.

Data source: Global Burden of Disease Study 2021.

Main outcome measures: Prevalent number, all age prevalence and age standardised prevalence of Parkinson's disease in 2050, and average annual percentage change of prevalence from 2021 to 2050; contribution of population ageing, population growth, and changes in prevalence to the growth in Parkinson's disease cases; population attributable fractions for modifiable factors.

Results: 25.2 (95% uncertainty interval 21.7 to 30.1) million people were projected to be living with Parkinson's disease worldwide in 2050, representing a 112% (95% uncertainty interval 71% to 152%) increase from 2021. Population ageing (89%) was predicted to be the primary contributor to the growth in cases from 2021 to 2050, followed by population growth (20%) and changes in prevalence (3%). The prevalence of Parkinson's disease was forecasted to be 267 (230 to 320) cases per 100 000 in 2050, indicating a significant increase of 76% (56% to 125%) from 2021, whereas the age standardised prevalence was predicted to be 216 (168 to 281) per 100 000, with an increase of 55% (50% to 60%) from 2021. Countries in the middle fifth of Socio-demographic Index were projected to have the highest percentage increase in the all age prevalence (144%, 87% to 183%) and age standardised prevalence (91%, 82% to 101%) of Parkinson's disease between 2021 and 2050. Among Global Burden of Disease regions, East Asia (10.9 (9.0 to 13.3) million) was projected to have the highest number of Parkinson's disease cases in 2050, with western Sub-Saharan Africa (292%, 266% to 362%) experiencing the most significant increase from 2021. The ≥80 years age group was projected to have the greatest increase in the number of Parkinson's disease cases (196%, 143% to 235%) from 2021 to 2050. The male-to-female ratios of age standardised prevalence of Parkinson's disease were projected to increase from 1.46 in 2021 to 1.64 in 2050 globally.

Conclusions: By 2050 Parkinson's disease will have become a greater public health challenge for patients, their families, care givers, communities, and society. The upward trend is expected to be more pronounced among countries with middle Socio-demographic Index, in the Global Burden of Disease East Asia region, and among men. This projection could serve as an aid in promoting health research, informing policy decisions, and allocating resources.

Fig 1

Equations used to construct models. Top: Poisson regression models. For each location (l), age group (a), sex (s), and year (y), Parkinson’s disease prevalence estimates were log transformed: log(Y_l,a,s,y). On right side of equation, β_l was fixed coefficient on forecasted Socio-demographic Index, β_a was fixed coefficient assigned to different age groups, and α_l,a,s was location, age, and sex specific random intercept. Bottom: bayesian model averaging (BMA) model. Y was prevalence of Parkinson’s disease. For each model (M) and location (l), β_l,M was fixed coefficient on prevalence of Parkinson’s disease. β_l,M for each model was calculated using bayesian information criterion

Fig 2

Estimated trends in global number of Parkinson’s disease (PD) cases (top), all age prevalence of PD (middle), and age standardised prevalence of PD (bottom), with 95% uncertainty intervals, 1990-2050. Solid lines represent values from Global Burden of Disease Study (1990-2021); dotted lines represent projected values (2022-50)

Fig 3

Projected trends of all age prevalence and age standardized prevalence of Parkinson’s disease from 2022 to 2050 globally and in locations grouped by Socio-demographic Index (SDI) fifths, with 95% uncertainty intervals

Fig 4

Estimated trends of numbers of Parkinson’s disease (PD) cases by Socio-demographic Index (SDI) fifths (top) and age groups (bottom), for both sexes combined, with 95% uncertainty intervals, 1990-2050. Solid lines represent values from Global Burden of Disease (1990-2021); dotted lines represent projected values (2022-50)

Fig 5

Projected age standardised prevalence (per 100 000) of Parkinson’s disease in 2050, by country and territory for both sexes combined

Fig 6

Projected average annual percentage change (AAPC) from 2021 to 2050, by country and territory for both sexes combined

Fig 7

Estimated top 10 countries with highest number of Parkinson’s disease (PD) cases in 1990, 2021, 2030, 2040, and 2050 globally. Corresponding boxes present number of PD cases in this country and their proportion among global PD patients, as well as global count

Fig 8

Decomposition of projected percentage change in number of people with Parkinson’s disease (PD) between 2021 and 2050 globally and by sex, Socio-demographic Index (SDI) fifths, and top 10 countries

Fig 9

Decomposition of projected percentage change in number of people with Parkinson’s disease (PD) between 2021 and 2050 by Global Burden of Disease regions