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A Short Commentary on the Racial Disparities in Parkinson’s Disease



The etiology of Parkinson Disease (PD) remains elusive, but may include environmental and genetic factors leading to neuronal degeneration [1]. The difference in incidence of PD among different racial groups may provide additional insight into the etiology. In 2004, McInerney-Leo et al. reviewed twenty studies analyzing the prevalence and incidence of PD among Caucasians, African-Americans in the United States and African populations [2]. The differences in prevalence of Parkinson’s disease and Parkinsonism could not be demonstrated because of poor designs and numerous biases, such as referral bias and differences in access to healthcare. Therefore, they were unable to determine the effect of race in PD. Yet, studies continue to suggest that there is a significantly higher prevalence of PD among Caucasians compared to other racial groups [3]
Short Commentary OMICS International
Branson and Saint-Hilaire, J Neurol Disord 2017, 5:2
DOI: 10.4172/2329-6895.1000338
Volume 5 • Issue 2 • 1000338
J Neurol Disord, an open access journal
ISSN: 2329-6895
Journal of Neurological Disorders
ISSN: 2329-6895
A Short Commentary on the Racial Disparities in Parkinsons Disease
Chantale Branson* and Marie-Helene Saint-Hilaire
Department of Neurology, Boston University School of Medicine, 72 E. Concord St, C3, Boston, MA, USA
Short Commentary
e etiology of Parkinson Disease (PD) remains elusive, but
may include environmental and genetic factors leading to neuronal
degeneration [1]. e dierence in incidence of PD among dierent
racial groups may provide additional insight into the etiology. In 2004,
McInerney-Leo et al. reviewed twenty studies analyzing the prevalence
and incidence of PD among Caucasians, African-Americans in the
United States and African populations [2]. e dierences in prevalence
of Parkinsons disease and Parkinsonism could not be demonstrated
because of poor designs and numerous biases, such as referral bias
and dierences in access to healthcare. erefore, they were unable
to determine the eect of race in PD. Yet, studies continue to suggest
that there is a signicantly higher prevalence of PD among Caucasians
compared to other racial groups [3]
We completed a literature review of studies that analyzed the
impact of racial disparities in diagnosis and treatment of PD [3]. A
search was performed in PubMed and Medline from 2004 to 2016, for
articles about racial disparities and Parkinsons disease. e time-frame
covered articles published aer the McInerney-Leo et al. review.
ere were twelve studies that analyzed prevalence, incidence
and perception of Parkinson’s disease among several races, but mostly
comparing African-Americans and Caucasians. Six of the twelve studies
included Hispanic or Latino, Asian, and Native American populations
[3]. Some studies also focused on disparities in treatment and patient
care [3].
All of the studies, whether using data from tertiary centers, databases
or death certicates, concluded that the prevalence and incidence of
PD was higher in Caucasians than in African-Americans. Studies using
information from databases, such as United States Medicare recipients,
Pennsylvania Medicaid claims or the Veterans Administration were able
to obtain accurate prevalence due to their large sample size, compared
with studies at tertiary movement disorders centers. For example,
Willis’ study of the US Medicare Database included 450,000 PD cases
per year [4]. ere was only one study that used death certicates to
understand the prevalence of PD, which highlighted socioeconomic
bias in reporting Parkinsons disease at death [5].
Several of the studies observed treatment disparities in PD
treatment among African-Americans compared to Caucasians [6-8].
e lack of treatment for PD can lead to increased morbidity, decreased
quality of life and cause more rapid progression to disability [8]. Aer
controlling for demographics, age, sex, geography and initial visit with
a neurologist, about only one third of African-Americans with PD
were started on any therapy, including physical therapy. While authors
were unable to determine the cause of the treatment disparities, the
ndings raised the possibility of problems with the quality of provider
communication [8]. African-Americans were also less likely to receive
Deep Brain Stimulation treatment for refractory PD despite being at a
tertiary center with a comprehensive neurology and neurosurgery team
[6]. ere were limitations with these studies as they were retrospective,
and based on Medicaid claims, ICD-9 charts and national database.
Dierences in PD prevalence can also be caused by patients’ own
perception of disease and expectation of aging, aecting decision to
*Corresponding author: Branson C, Department of Neurology, Boston University
School of Medicine, MA, USA, Tel: 6176387729; E-mail:
Received April 06, 2017; Accepted April 26, 2017; Published April 28, 2017
Citation: Branson C, Saint-Hilaire M (2017) A Short Commentary on the Racial
Disparities in Parkinson’s Disease. J Neurol Disord 5: 338. doi:10.4172/2329-
Copyright: © 2017 Branson C, et al. This is an open-access article distributed
under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the
original author and source are credited.
seek care. ere was one mixed-methods study that analyzed the
knowledge and attitude about Parkinson’s disease among older adults
[9]. Barriers to PD care included level of knowledge, lack of trust in the
healthcare system, language problems and attitudes about PD, such as
underreporting [10].
Hospital and out-patient based studies are not ideal study designs
to provide eective analysis of PD incidence or prevalence given
confounders, such as socioeconomic status, cultural factors, and
selection of the population being referred to a specialized center [11].
Further studies are needed, and should include a long-term community
based prospective design. is type of design would improve the overall
biases found in retrospective studies, and better assess if there is delay in
diagnosis, or under-diagnosis of Parkinson’s disease. is type of study
has yet to be performed. So far we are still unable to determine a clear
cause for the observed racial dierences in diagnosis and treatment of
Parkinson’s disease.
e limitations of our review article included a lack of studies
analyzing incidence, which may provide a direct link between race and
risk of PD. ere were a few articles that discussed incidence within
their cross-sectional study design, but none of the studies included
a prospective cohort design [4,12]. e article did not fully address
demographic variables that may also indirectly link race to risk of PD,
such as rural areas compared to urban areas.
All the above studies revealed racial dierences in the diagnosis and
treatment of PD that were not explained by location of care, insurance,
income, healthcare utilization, clinical factors, age, sex, geography or
initial visit with a neurologist. Many of the studies concluded that the
dierences were explained by racial disparities, dened as partiality or
inequity. e types of disparities included patient’s knowledge, as well
as expectation of the disease process, diagnosis with underreporting
and treatment from physical therapy, PD medications and deep brain
stimulation. Additional studies evaluating genetic factors or biological
factors, such as a population-based study are needed to further
understand PD prevalence.
1. Pringsheim T, Jette N, Frolkis A, Steeves TDL (2014) The prevalence of
Parkinson’s disease: A systematic review and meta-analysis. Movement
Disorders 29: 1583-1590.
2. McInerney-Leo A, Gwinn-Hardy K, Nussbaum RL (2004) Prevalence of
Parkinson’s disease in populations of African ancestry: A review. J Natl Med
Assoc 96(7): 974-979.
3. Branson CO, Ferree A, Hohler AD, Saint-Hilaire MH (2016) Racial disparities
Citation: Branson C, Saint-Hilaire M (2017) A Short Commentary on the Racial Disparities in Parkinson’s Disease. J Neurol Disord 5: 338. doi:10.4172/2329-
Page 2 of 2
Volume 5 • Issue 2 • 1000338
J Neurol Disord, an open access journal
ISSN: 2329-6895
in Parkinson’s disease: A Systematic Review of the Literature. Advances in
Parkinson’s Disease 5(4): 87-96.
4. Willis WA, Evanoff BA, Lian M, Criswall SR, Racette BA (2010) Geographic and
ethnic variation in Parkinson disease: A population-based study of US Meidcare
beneciaries. Neuroepidemiology. 34(3): 143-151.
5. Pressley JC, Tang MX, Marder K, Cote LJ, Mayeux R (2005) Disparities in
the recording of Parkinson’s disease on death certicates. Movement disorders
20(3): 315-321.
6. Chan AK, McGovern RA, Brown LT, Sheehy JP, Zacharia BE, et al. (2014)
Disparities in access to deep brain stimulation surgery for Parkinson disease:
Interaction between African American race and medicaid use. JAMA Neurology
71: 291-299.
7. Cheng EM, Siderowf AD, Swarztrauber K, Lee M, Vassar S, et al. (2008)
Disparities of care in veterans with Parkinson’s disease. Parkinsonism &
Related Disorders 14: 8-14.
8. Dahodwala N, Xie M, Noll E, Siderowf A, Mandell DS (2009) Treatment
disparities in Parkinson’s disease. Annals of Neurology 66: 142-145.
9. Pan S, Stutzbach J, Reichwein S, Lee BK, Dahodwala N (2014) Knowledge
and attitudes about Parkinson’s disease among a diverse group of older adults.
Journal of Cross-cultural Gerontology. 29(3): 339-352.
10. Dahodwala N, Karlawish J, Siderowf A, Duda JE, Mandell DS (2011) Delayed
Parkinson’s disease diagnosis among African-Americans: The role of reporting
of disability. Neuroepidemiology 36(3): 150-154.
11. Hemming JP, Gruber-Badini AL, Anderson KE, Fishman PS, Reich SG, et
al. (2011) Racial and socioeconomic disparities in Parkinsonism. Archives of
neurology. 68(4): 498-503.
12. Dahodwala N, Siderowf A, Xie M, Noll E, Stern M, et al. (2009) Racial
differences in the diagnosis of Parkinson’s disease. Movement Disorders 24(8):
Citation: Branson C, Saint-Hilaire M (2017) A Short Commentary on the Racial
Disparities in Parkinson’s Disease. J Neurol Disord 5: 338. doi:10.4172/2329-
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Racial differences in the prevalence of Parkinson’s disease (PD) have been reported for decades. Many of the earliest reports were flawed because they were based on crude datasets, such as hospital databases, death certificates, door-to-door surveys and records of Medicare beneficiaries. These studies provided conflicting results and were found to have numerous biases. Publications with improved study designs in recent years have yielded higher quality findings that are worth reviewing. We reviewed studies published between 2005 and 2014 that analyzed the racial differences in Parkinson’s disease diagnosis, treatment—including deep brain stimulation—and access to care. Literature searches were conducted in PubMed and EBSCO. These studies highlight advances in the field and explore differences in PD among ethnic and racial groups. Our literature review focused on prevalence, treatment and diagnosis discrepancies, and racial variations in the perceptions of aging. An appraisal of twelve reviewed studies determined a decrease in prevalence and incidence of PD in Americans of African descent compared to Caucasians. The studies also showed multiple health disparities, including lack of access to care, treatment, and inclusion in research. More studies are needed to address the causes and prevention of health disparities, as well as solutions, such as community outreach.
Full-text available
Racial differences in the observed prevalence of Parkinson's disease (PD) may be due to delayed diagnosis among African-Americans. We sought to compare the stage at which African-American and white PD patients present for healthcare, and determine whether perception of disability accounts for racial differences. Using records of veterans with newly diagnosed PD at the Philadelphia Veterans Affairs Medical Center, we calculated differences in reporting of symptoms as the difference in z-scores on the Unified Parkinson Disease Rating Scale part 2 (disability) and part 3 (motor impairment). Ordinal logistic regression was used to determine predictors of stage at diagnosis. African-American (n = 16) and white (n = 58) veterans with a mean age of 70.1 years were identified. African-Americans presented at a later PD stage than whites (median Hoehn + Yahr stage 2.5 vs. 2.0, p = 0.02) and were more likely to under-report disability relative to motor impairment (81 vs. 40%, p < 0.01). Multivariate analysis showed that under-reporting of disability accounted for much of the effect of race on stage of diagnosis. Under-reporting of disability among African-Americans may account for later stages of PD diagnosis than whites. This study begins to explain the mechanisms underlying observed racial disparities in PD.
Full-text available
Parkinson disease is a common neurodegenerative disease. The racial, sex, age, and geographic distributions of Parkinson disease in the US are unknown. We performed a serial cross-sectional study of US Medicare beneficiaries aged 65 and older from the years 1995, and 2000-2005. Using over 450,000 Parkinson disease cases per year, we calculated Parkinson disease prevalence and annual incidence by race, age, sex, and county. Spatial analysis investigated the geographic distribution of Parkinson disease. Age-standardized Parkinson disease prevalence (per 100,000) was 2,168.18 (+/-95.64) in White men, but 1,036.41 (+/-86.01) in Blacks, and 1,138.56 (+/-46.47) in Asians. The incidence ratio in Blacks as compared to Whites (0.74; 95% CI = 0.732-0.748) was higher than the prevalence ratio (0.58; 95% CI = 0.575-0.581), whereas the incidence ratio for Asians (0.69; 95% CI = 0.657-0.723) was similar to the prevalence ratio (0.62; 95% CI = 0.617-0.631). Bayesian mapping of Parkinson disease revealed a concentration in the Midwest and Northeast regions. Mean county incidence by quartile ranged from 279 to 3,111, and prevalence from 1,175 to 13,800 (per 100,000). Prevalence and incidence in urban counties were greater than in rural ones (p < 0.01). Cluster analysis supported a nonrandom distribution of both incident and prevalent Parkinson disease cases (p < 0.001). Parkinson disease is substantially more common in Whites, and is nonrandomly distributed in the Midwest and Northeastern US.
Full-text available
There have been a number of studies looking at the prevalence of Parkinson's disease (PD) in different racial and geographical populations. Some of the earliest studies suggested a difference in the prevalence of PD in African Americans as compared with Caucasians. As such a difference would have important implications for healthcare and research into the etiology of PD, we undertook a review of published studies to determine whether evidence suggested that such a difference exists. We reviewed 20 studies that looked at incidence, prevalence, and percentages of neurology patients with PD and Parkinsonism in Africa and in African-American populations. Two of these were door-to-door studies that relied on questionnaires for initial ascertainment, another was performed by review of outpatient records of a large health maintenance organization, while the remainder were based on hospital admissions, diagnosis in the community, or death certificate reports. In the aggregate, these studies suggest PD may be less frequent among Africans and African Americans than among Caucasians, although the most well-designed study showed only a statistically insignificant reduction in the prevalence of PD among African Americans. Although an apparently lower disease frequency among people of African origin may have a basis in the pathobiology of the disease, nearly all of these studies were vulnerable to a variety of ascertainment biases, and many lacked stringent application of diagnostic criteria applied by specialists trained in movement disorders. We conclude that a difference in the prevalence of PD and Parkinsonism between black and other populations is unproven and will require additional well-designed studies to determine if previously reported ethnic differences in disease prevalence are real.
Background: Parkinson's disease (PD) is a common neurodegenerative disorder. Epidemiological studies on the incidence of PD are important to better understand the risk factors for PD and determine the condition's natural history. Objective: This systematic review and meta-analysis examine the incidence of PD and its variation by age and gender. Methods: We searched MEDLINE and EMBASE for epidemiologic studies of PD from 2001 to 2014, as a previously published systematic review included studies published until 2001. Data were analyzed separately for age group and gender, and meta-regression was used to determine whether a significant difference was present between groups. Results: Twenty-seven studies were included in the analysis. Meta-analysis of international studies showed rising incidence with age in both men and women. Significant heterogeneity was observed in the 80+ group, which may be explained by methodological differences between studies. While males had a higher incidence of PD in all age groups, this difference was only statistically significant for those in the age range 60-69 and 70-79 (p < 0.05). Conclusion: PD incidence generally increases with age, although it may stabilize in those who are 80+.
Underserved minorities are vulnerable to diagnostic delays and under-treatment of Parkinson's disease (PD). The purpose of this mixed-methods study was to understand knowledge and attitudes about PD among a racially/ethnically diverse group of community members. In the qualitative arm, ten homogeneous focus groups of 6 to 8 White, African-American and Chinese American older adults at senior centers in Philadelphia were conducted. Next, for the quantitative arm, a questionnaire of knowledge and attitudes about PD was administered among a larger group of senior center members. Themes were identified from the focus group discussions. ANOVA and chi-square tests were used to assess differences in PD knowledge and attitudes among the different racial/ethnic groups. Logistic regression analyzed for independent factors associated with barriers to treatment. Seventy-five adults participated in the focus groups (23 Whites, 36 African-Americans and 16 Chinese-Americans) and 154 completed the questionnaire (62 Whites, 47 African-Americans and 45 Chinese-Americans). One common theme about developing PD was fear of losing independence. Racial/ethnic groups identified unique barriers to care: mistrust in the healthcare system by African-Americans and language difficulties by Chinese-Americans. Eighty percent of all participants had no to some knowledge of PD. African-Americans and Chinese-Americans were more likely to perceive PD as a part of normal aging than whites. Chinese-Americans were more likely to perceive barriers to treatment than whites. A diverse sample of older adults demonstrated low levels of PD knowledge through both qualitative and quantitative methods. Many barriers to PD care were identified. Targeted community outreach and education efforts should incorporate information about PD and how to receive care.
Importance: African American individuals experience barriers to accessing many types of health care in the United States, resulting in substantial health care disparities. To improve health care in this patient population, it is important to recognize and study the potential factors limiting access to care. Objective: To examine deep brain stimulation (DBS) use in Parkinson disease (PD) to determine which factors, among a variety of demographic, clinical, and socioeconomic variables, drive DBS use in the United States. Design, setting, and participants: We queried the Nationwide Inpatient Sample in combination with neurologist and neurological surgeon countywide density data from the Area Resource File. We used International Classification of Diseases, Ninth Revision codes to identify discharges of patients at multicenter, all-payer, nonfederal hospitals in the United States diagnosed with PD (code 332.0) who were admitted for implantation of intracranial neurostimulator lead(s) (code 02.39), DBS. Main outcomes and measures: We analyzed factors predicting DBS use in PD using a hierarchical logistic regression analysis including patient and hospital characteristics. Patient characteristics included age, sex, comorbidity score, race, income quartile of zip code, and insurance type. Hospital characteristics included teaching status, size, regional location, urban vs rural setting, experience with DBS discharges, year, and countywide density of neurologists and neurological surgeons. Results: Query of the Nationwide Inpatient Sample yielded 2,408,302 PD discharges from 2002 to 2009; 18,312 of these discharges were for DBS. Notably, 4.7% of all PD discharges were African American, while only 0.1% of DBS for PD discharges were African American. A number of factors in the hierarchical multivariate analysis predicted DBS use including younger age, male sex, increasing income quartile of patient zip code, large hospitals, teaching hospitals, urban setting, hospitals with higher number of annual discharges for PD, and increased countywide density of neurologists (P < .05). Predictors of nonuse included African American race (P < .001), Medicaid use (P < .001), and increasing comorbidity score (P < .001). Countywide density of neurological surgeons and Hispanic ethnicity were not significant predictors. Conclusions: AND RELEVANCE: Despite the fact that African American patients are more often discharged from hospitals with characteristics predicting DBS use (ie, urban teaching hospitals in areas with a higher than average density of neurologists), these patients received disproportionately fewer DBS procedures compared with their non-African American counterparts. Increased reliance on Medicaid in the African American population may predispose to the DBS use disparity. Various other factors may be responsible, including disparities in access to care, cultural biases or beliefs, and/or socioeconomic status.
To assess potential racial and socioeconomic disparities in patients with parkinsonism treated at a tertiary Movement Disorders Center. Patients with parkinsonism were evaluated for demographics (age, race, annual income, and educational level), medical comorbidities, medication regimen, disability (Older Americans Resources and Services subscale), presence of Parkinson disease, and disease severity (Unified Parkinson Disease Rating Scale). Disability and disease severity measures were compared by race, income, and educational level using analysis of variance for continuous variables and χ(2) tests for dichotomous variables. The sample included 1159 patients with parkinsonism (93.4% white, 6.1% African American, 61.2% who earned more than $50,000 annually, 62.7% who completed college, and 79.2% with a diagnosis of Parkinson disease). Cross-sectional analyses by race, income, and educational level showed greater disability and disease severity in African American compared with white patients (African American vs white Older Americans Resources and Services subscale total score, 29.8 vs 25.3, P = .005; Unified Parkinson's Disease Rating Scale total score, 53.0 vs 42.8; P < .001). African Americans were less likely to be prescribed dopaminergic medications, particularly newer agents (African Americans 20.6% vs whites: 41.1%; P = .01). Lower income and lower educational level were independently associated with greater disease severity and disability (P < .003). Racial and socioeconomic disparities exist among patients with parkinsonism being treated at a tertiary Movement Disorders Center. African Americans and those with lower socioeconomic status have greater disease severity and disability than whites. These disparities may be because of problems in diagnosis, access to care, physician referrals, and patient attitudes regarding the appropriate threshold for seeking treatment at a specialized center. Understanding and correction of these disparities may improve outcomes.
We sought to identify racial disparities in the treatment of Parkinson's disease (PD). We identified 307 incident PD cases using Pennsylvania State Medicaid claims, and extracted claims for medications, physical therapy, and healthcare visits for the 6 months after diagnosis. After controlling for age, sex, and geography, African-Americans were four times less likely than whites to receive any PD treatment (odds ratio, 0.24; 95% confidence interval, 0.09-0.64), especially indicated medications. In a group with the same healthcare insurance, disparities in PD treatment exist. Physician and community awareness of these racial differences in PD treatment is the first step in addressing healthcare disparities.
The objective of this cohort study was to determine the incidence of Parkinson's disease (PD) and the effects of race/ethnicity, other demographic characteristics, geography, and healthcare utilization on probability of diagnosis. The authors used the Pennsylvania state Medicaid claims dataset from 1999 to 2003 to identify newly diagnosed cases of PD among the 182,271 Medicaid enrolled adults age 40-65; 319 incident cases of PD were identified. The 4-year cumulative incidence of PD was 45 per 100,000; 54 per 100,000 among whites, 23 per 100,000 among African-Americans and 40 per 100,000 among Latinos (P < 0.0001), corresponding to a relative risk (RR) of PD of 0.43 for African-Americans (P < 0.0001) compared with whites. After adjusting for age, sex, geography, reason for Medicaid eligibility, and average number of visits, African-Americans were still half as likely to be diagnosed with PD as whites (RR 0.45, P < 0.0001). Older age, more healthcare visits and Medicaid eligibility because of income alone also were significantly associated with PD diagnosis, while male sex was not. Observed racial differences in incidence of PD are not explained by differences in age, sex, income, insurance or healthcare utilization but still may be explained by biological differences or other factors such as education or aging beliefs. Better understanding of the complex biological and social determinants of these disparities is critical to improve PD care.