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. 2023 Jan 27:8:100185.
doi: 10.1016/j.prdoa.2023.100185. eCollection 2023.

Time trends in demographic characteristics of participants and outcome measures in Parkinson's disease research: A 19-year single-center experience

Bart R Maas  1 , Bastiaan R Bloem  1 , Yoav Ben-Shlomo  2 , Luc J W Evers  1 , Rick C Helmich  1 , Johanna G Kalf  3 , Marjolein A van der Marck  4 , Marjan J Meinders  1   5 , Alice Nieuwboer  6 , Maarten J Nijkrake  3 , Jorik Nonnekes  3   7 , Bart Post  1 , Ingrid H W M Sturkenboom  3 , Marcel M Verbeek  1   8 , Nienke M de Vries  1 , Bart van de Warrenburg  1 , Tessa van de Zande  1 , Marten Munneke  1 , Sirwan K L Darweesh  1
Affiliations

Time trends in demographic characteristics of participants and outcome measures in Parkinson's disease research: A 19-year single-center experience

Bart R Maas et al. Clin Park Relat Disord. .

Abstract

Background: Females, people with young-onset PD and older individuals, and non-white populations are historically underrepresented in clinical Parkinson's disease (PD) research. Furthermore, research traditionally focused predominantly on motor symptoms of PD. Including a representative and diverse group of people with PD and also studying non-motor symptoms is warranted to better understand heterogeneity in PD and to generalize research findings.

Objective: This project aimed to determine whether, within a consecutive series of PD studies performed within a single center in the Netherlands: (1) the proportion of included females, mean age and proportion of native Dutch people changed over time; and 2) reports of the ethnicity of participants and the proportion of studies with non-motor outcomes changed over time.

Methods: Characteristics of participants and non-motor outcomes were analyzed using a unique dataset of summary statistics of studies with a large number of participants conducted at a single center during a 19-year period (2003-2021).

Results: Results indicate no relationship between calendar time and proportion of females (mean 39 %), mean age (66 years), proportion of studies that reported ethnicity, and proportion of native Dutch people in studies (range 97-100 %). The proportion of participants in whom non-motor symptoms were assessed increased, but this difference was consistent with chance.

Conclusion: Study participants in this center reflect the PD population in the Netherlands in terms of sex, but older individuals and non-native Dutch individuals are under-represented. We have still a lot to do in ensuring adequate representation and diversity in PD patients within our research.

Keywords: Age; Demographics; Diversity; Ehtnicity; Elderly; Females; Gender; Non-motor symptoms; Outcome measure; Parkinson's disease; Parkinsonism; Participant characteristics; Representative; Sex; Time trends; Underrepresentation; Young-onset.

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Conflict of interest statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Fig. 1
Fig. 1
Proportion of females. Forest plot showing proportion of females and 95% confidence intervals for each study performed at our center. The vertical grey line indicates the mean proportion of females (weighted for study size) in studies in our center over the entire study period. The number of participants in each study is shown as well.
Fig. 2
Fig. 2
Age over time. Forest plot showing the mean age and 95% confidence intervals of participants per study performed at our center. The vertical grey line indicates the overall mean age of participants (weighted for study size) in all studies in our center. The number of participants in each study is shown as well.
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