December 20, 2010 — A study of patients with parkinsonism seen at a tertiary movement disorders center shows clear differences based on race and socioeconomic status in disease severity, level of disability, and treatment.
African American patients and those of lower socioeconomic status had more severe disease and greater disability than whites and those with higher incomes and were less apt to be prescribed the latest antiparkinsonian medications.
“The next step is to investigate why this occurs,” said Lisa M. Shulman, MD, codirector of the University of Maryland Parkinson’s Disease & Movement Disorders Center in Baltimore, where the study was conducted.
“These disparities may be due to problems in diagnosis, access to care, conscious or unconscious physician attitudes about referral, or differences in patient attitudes about the appropriate threshold to seek treatment at a specialized center,” she told Medscape Medical News.
The findings were published online December 13 and will appear in the April 2011 print issue of Archives of Neurology.
A Tale of Opposites
The study sample included 1090 patients evaluated at the center between 2003 and 2008. The demographics of the sample did not match that of the surrounding area — 93.4% were white, 6.1% were African American, 61.2% earned more than $50,000 annually, 62.7% completed college, and 79.2% had been diagnosed as having Parkinson’s disease.
“Since the [center] is located in downtown Baltimore, where the majority of the population is African American and both low income and low educational attainment is common, the presence of the opposite population demographics in our patient population is of great concern,” Dr. Shulman noted. It suggests that minorities and those with low socioeconomic status are less likely to receive specialized care, she said.
When compared with white patients, African American patients had more severe parkinsonism, scoring roughly 10 points higher on the total Unified Parkinson Disease Rating Scale (UPDRS). This is a “striking” difference that may influence mortality, the study authors say.
African Americans also had worse (higher) scores on a modified version of the Older Americans Resources and Services (OARS) disability subscale, which assesses the level of difficulty for 14 daily activities.
Table 1. Disability and Disease Severity by Race
| Score |
White PD Patients |
African American PD Patients |
P Value |
| OARS total score |
25.3 |
29.8 |
<.01 |
| UPDRS motor score |
27.9 |
35.1 |
<.001 |
| UPDRS total score |
42.8 |
53.0 |
<.001 |
OARS = Older Americans Resources and Services; PD = Parkinson disease; UPDRS = Unified Parkinson Disease Rating Scale
Independent of race, lower income and lower educational level were also associated with greater disease severity and disability. For example, between the high- and low-income groups, the UPDRS total score differed by nearly 15 points and the total OARS scores were nearly 10 points apart. The differences by income and education remained significant but were less pronounced after controlling for covariates (P < .001 for both).
Table 2. Disability and Disease Severity by Income and Education
| Measure |
OARS Total Score |
P Value |
UPDRS Total Score |
P Value |
| Annual income, $ |
|
|
|
|
| <30,000 |
29.9 |
|
50.4 |
|
| >70,000 |
20.5 |
<.001 |
35.6 |
<.001 |
| Educational level |
|
|
|
|
| Lower than college |
28.8 |
|
49 |
|
| College or higher |
23.1 |
<.001 |
39.3 |
<.001 |
OARS = Older Americans Resources and Services; UPDRS = Unified Parkinson Disease Rating Scale
Treatment Differences
“We did not anticipate the very large differences found in disease severity and disability between these patient populations,” Dr. Shulman told Medscape Medical News. “We need to learn more about whether these large differences are related to the timing of presentation for medical care, differences in medical comorbidities, disparities in treatments, or other factors.”
Although there were differences between African American and white patients in the level of medical comorbidity, the difference was not significant (P = .10). There were, however, marked disparities in treatment patterns.
At the first visit, 77.6% of whites were prescribed an antiparkinson drug vs 61.9% of African Americans (P < .01). Fewer African Americans than whites were prescribed newer dopaminergic agents, such as catechol-O-methyltransferase inhibitors, dopamine agonists, and monoamine oxidase inhibitors (20.6% vs 41.1%; P < .01). In contrast, African Americans were more likely than whites to be prescribed an antipsychotic medication (12.7% vs 6.1%; P < .05).
Income level was not a factor in the overall receipt of antiparkinsonian medications; however, 30.0% of patients making less than $30,000 annually were prescribed newer dopaminergic agents compared with 47.2% of those making more than $70,000 (P = .002).
The use of carbidopa-levodopa without newer add-on agents was also more common at the lower income level (67.3% vs 56.7%; P = .03). Lower-income patients were also significantly more apt to be prescribed antidepressants (P = .004), antipsychotics (P = .001), and antidementia agents (P = .03).
Use of antiparkinsonian drugs was similar across educational levels except with regard to the newer agents, with 43.0% of college-educated patients receiving them vs 35.3% of those with less than a college education (P = .002). Less educated patients were also more apt to receive an antipsychotic (8.4% vs 4.7% of college-educated patients; P = .01).
Study Adds to Prior Research
Reached for comment, Nabila Dahodwala, MD, a neurologist at the Pennsylvania Hospital in Philadelphia, who was not involved in the study, said the findings support “the few prior studies that have detected healthcare disparities in Parkinson’s disease.
“In addition, these researchers have explored the complex relationship between race, education, and income. It is important to untangle these confounding factors so that we can truly understand the underlying mechanisms of health disparities,” Dr. Dahodwala said.
One limitation of the study, Dr. Dahodwala said, is that all patients were selected from a single tertiary referral center. “These patients may not be representative of all patients with Parkinson’s disease since only a minority of patients receives care at specialty referral centers,” she noted.
Dr. Shulman and colleagues agree, noting in their report that the setting for the study — a single urban academic movement disorders clinic — limits the generalizability of the findings.
The small number of African Americans in the sample (n = 66) is another limitation, the researchers say, one that may have hindered the ability to detect differences. In addition, the demographics of the center did not permit analysis of racial groups other than African Americans. “Studies in different patient populations and geographic locations are necessary to confirm these findings,” Dr. Shulman and colleagues write.
“Ultimately, we need to invest more in understanding what causes health disparities so that we can reduce them,” Dr. Dahodwala added. “We can accomplish this goal through collaboration across disciplines where health disparities are present and identification of what is unique about disparities in Parkinson’s disease.”
Dr. Shulman has received compensation from Teva Pharmaceutical Industries Ltd and Boehringer Ingelheim GmbH. A complete list of author disclosures can be found with the original article. Dr. Dahodwala has disclosed no relevant financial relationships.
Arch Neurol. Published online December 13, 2010.
Medscape Medical News © 2010 WebMD, LLC
