Mechanisms of inequitable access to parkinson's disease care: a critical interpretive synthesis.

Background: Parkinson's disease (PD) is a leading cause of neurological disability among older adults, with an age-standardized global prevalence in 2021 of 139/100,000 and projected to increase by 112% by 2050. People living with PD experience seven times worse health status than the general population. Access to diagnosis, care, and support is particularly challenged by intersecting social and healthcare system complexities. This Critical Interpretive Synthesis aimed to identify mechanisms through which barriers interact to create inequitable access to PD care among underserved populations.

Methods: We searched five bibliographic databases (MEDLINE, Embase, CINAHL, PsychINFO, and Scopus) for English-language sources (2005 to 2024). Inclusion criteria encompassed peer-reviewed articles, books, dissertations, and organizational reports mentioning underserved older adults with PD and their care partners. Analysis followed Critical Interpretive Synthesis methodology, combining systematic review strategies with meta-ethnography and grounded theory techniques. Two investigators independently screened citations, with analysis guided by Candidacy 2.0 and Intersectionality frameworks.

Results: Of 1,281 identified studies, 96 met inclusion criteria. United States studies dominated (56%), with quantitative analyses of electronic medical records comprising 66% of evidence. Analysis revealed three interrelated mechanisms shaping access inequities: (1) complex interplay between regional factors and healthcare delivery systems creating variable landscapes of access, (2) provider biases and judgments serving as critical gatekeeping points, and (3) intersectional effects of multiple marginalized identities compounding disadvantage. These mechanisms interact systematically, creating self-reinforcing cycles where social marginalization increases both disease progression and barriers to appropriate care.

Conclusions: Improving PD care access requires coordinated interventions addressing multiple intersecting barriers simultaneously. For policy and management, this includes targeted funding for infrastructure, systematic provider education addressing knowledge gaps and biases, and integration of community-based solutions with formal healthcare. Future research should examine how informal care networks can enhance access in diverse healthcare contexts.

Registration: The scoping review on which this Critical Interpretive synthesis builds is registered with Open Science Framework: https://doi.org/10.17605/OSF.IO/2T7KG .