Neurologic Disorders Genetic Testing Patterns Highlight Racial Disparities

There is a demographically unequal utilization of the University of Pennsylvania’s neurogenetics program, especially among Black patients, according to study results published in Neurology.

Researchers conducted a retrospective cohort study between January 2015 and September 2022 to evaluate whether disparities across 5 demographic variables (race, ethnicity, sex, socioeconomic status, and insurance type) persist between marginalized and privileged groups at any transition between 3 steps along the genetic evaluation pathway: attending a neurogenetics visit, completing the recommended genetic testing, and receiving a diagnostic result. The privileged group was defined as the reference category for each demographic variable (race, White; ethnicity, Not Hispanic or Latino; sex, men; socioeconomic status, highest quartile of median household income; insurance, private).

To determine whether members of other demographic categories were less likely than members of privileged categories to advance to each step of the evaluation pathway, the researchers obtained odds ratios (ORs) with 95% CIs and 2-sided P-values from Fisher exact tests.

They also conducted a multivariable analysis to examine the relationship among different demographic factors. This analysis was then restricted to patients with the 7 most common neurologic indications for genetic testing (amyotrophic lateral sclerosis, ataxia, dementia, epilepsy, myopathy, neuropathy, and Parkinson disease). Lastly, they did a post-hoc analysis using a Wilcoxon rank sum test to explore the potential causes of the observed disparities.

Of the 128,440 patients (White, 73%; women, 59%) seen in the outpatient neurology clinic, 2540 underwent a neurogenetics visit, 2082 completed genetic testing, and 487 received a diagnostic result. Compared with White patients, Black patients were less likely to have a neurogenetics visit (OR, 0.49; 95% CI, 0.42-0.55; P <.001). Compared with patients living in more wealthy quartiles of zip codes, patients living in the least wealthy quartile of zip codes were also less likely to be genetically evaluated (OR, 0.67; 95% CI, 0.59-0.75; P <.001).

After adjusting for differences in ethnicity, socioeconomic status, and insurance status, Black patients were still less likely than White patients to have a neurogenetics visit (OR, 0.51; 95% CI, 0.42-0.61). This was the only demographic category to demonstrate disparities in the multivariable regression.

The results of the restricted multivariable analysis were mostly consistent with the results of the primary analysis. Compared with their respective reference groups, Black patients and patients from the lowest quartile of socioeconomic status were still significantly less likely to access the neurogenetics program (OR, 0.67; 95% CI, 0.57-0.79 and OR, 0.81; 95% CI, 0.70-0.94, respectively). Unlike in the primary analysis, multivariable analysis revealed that patients with Medicaid vs those with private insurance were less likely to attend a neurogenetics visit (OR, 0.71; 95% CI, 0.56-0.89; P =.02).

In post-hoc analysis of patients with the 7 most common referring diagnoses who did attend a neurogenetics visit, the number of neurology office visits made prior to a neurogenetics visit was greater for Black patients (median, 16 visits; interquartile range [IQR], 8-40) than for White patients (median, 14 visits, IQR, 7-28; Wilcoxon P <.001).

Study limitations included the potential underestimation of disparities due to an outpatient population that did not accurately reflect the racial makeup of the greater Philadelphia metro area. Similarly, this study was conducted at as single center, limiting the generalizability of the results. Lastly, this study did not capture data related to genetic testing performed outside of the program and without the involvement of a genetic counselor.

“Understanding the underlying causes of disparities is critical because different causes will have different solutions, for example, targeting the referring providers vs increasing community trust and engagement,” the researchers concluded. 

Disclosures: This study was supported by the Vice Provost for Research University Research Foundation, University of Pennsylvania. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.