Ethnic and Gender Disparities in Access to Deep Brain Stimulation Surgery for Parkinson's Disease

Abstract

Background

Deep brain stimulation (DBS) is an established treatment for Parkinson's disease (PD) in appropriately selected patients. DBS may be underused in certain patient populations, especially women and racialized groups. Barriers and biases to receiving DBS that could account for underuse among these groups are not well studied in Canada.

Objective

We aim to better characterize the disparities in gender, ethnicity and other demographic factors among patients referred for and receiving DBS.

Methods

We performed a retrospective chart review and phone survey of DBS patients treated at two Canadian centers and from Canada Open Parkinson Network (C‐OPN). Gender, ethnicity, marital status, native language, birth country, urban versus rural residency, level of education, household income and mode of referral were studied.

Results

Among all participants, more men than women received DBS. Most patients (81.8–94.1%) in both referral and implanted groups were White. The gender and ethnicity of this cohort do not represent Canadian demographics. Patients referred and receiving surgery had higher educational level compared with general Canadian population. Being married was positively associated with DBS referral and implantation.

Conclusion

Significant ethnic and gender disparities in receiving DBS exist. Educated White men were overrepresented. Further actions need to be taken to expand the accessibility of this important treatment to all eligible PD patients with an effort to provide equitable care to women, racialized groups and those who cannot advocate for themselves in Canada.

Deep brain stimulation (DBS) is efficacious and safe in appropriately selected people with Parkinson's disease (PD) and improves quality of life. ¹ , ² DBS is a cost‐effective treatment that improves motor function, including tremor, bradykinesia/akinesia, rigidity, and motor complications such as excessive off time and disabling dyskinesia.

Unfortunately, DBS is under‐utilized in certain patient populations, especially women ³ , ⁴ , ⁵ and racialized groups. ⁵ , ⁶ , ⁷ In Ontario, PD patients in neighborhoods with the highest concentration of racialized minorities had a lower chance of receiving DBS surgery compared to patients in neighborhoods whose population is White predominant. ⁵ These differences represent discrepancies in care, contrary to Canada's philosophy of equal access to quality healthcare. ⁸ The Canadian healthcare system is governed by the Canada Health Act, which mandates equal access to all medically necessary therapies. ⁸ Detailed investigations into the factors limiting access to DBS in women and racialized people remain very limited, especially in the publicly funded Canadian system. Interventional studies aiming to improve disparities are also lacking.

Ethnic and racial disparities are well‐known in medical practice and research. Black women are 41% more likely to die of breast cancer than White women, but are vastly underrepresented in treatment research. ⁹ Ethnic disparities have also been investigated in PD with respect to quality of life, ¹⁰ motor and non‐motor symptoms, ¹¹ where White patients often experience improved outcomes in these domains compared to non‐White patients.

Other healthcare research demonstrates that ethnicity and gender impact interactions with the healthcare system. The severity and nature of symptoms expressed by racialized individuals with PD may be downplayed by providers/assessors. ¹² , ¹³ Additionally, racialized individuals may experience greater mistrust in healthcare systems due to historical and ongoing experiences of discrimination, which may contribute to hesitancy in engagement with their healthcare. ¹⁴ , ¹⁵ First generation immigrants may have less knowledge about how to navigate the health system. ¹⁶ Potential language difficulties can lead to inadequate communication. ¹⁷ Moreover, individuals from different ethnic backgrounds and age groups vary in behavior, comorbidities, and attitude towards healthcare and treatment options. ¹⁸ , ¹⁹ Cultural sensitivity to how patients experience and communicate their symptoms as well as understanding how medical information is received and processed is important. In certain cultures, caregivers and patients consider PD as “part of normal aging,” which may impact decision‐making. It is more common to see women reporting greater severity of symptoms and having a longer disease duration prior to DBS, partly due to their denial of disability and avoidance of device‐aided therapies. ²⁰ , ²¹ , ²² , ²³ Without systematic effort to ensure that individuals from all backgrounds are respected and supported, it is impossible to provide equitable opportunity to care access and benefits. It is equally important that researchers consider removing systemic barriers and biases to give all individuals equitable opportunity to access and benefit from the research ecosystem.

With an objective of better characterizing the disparities in DBS access, we studied the demographics of patients referred for and receiving DBS in two Canadian academic centers—the catchment area of University of Alberta (UA) which includes north Alberta, the Northwest Territories, Yukon, and Nunavut; the catchment area of Saskatoon, Saskatchewan; and the Canadian‐Open Parkinson Network (C‐OPN) database (https://copn-rpco.ca/), which is the largest national PD registry in Canada, which has enrolled over 1500 PD patients from eight academic sites across Canada. The patient population is representative for DBS practice in the country.

Methods

Research Participants

Five cohorts were recruited from the UA Parkinson and Movement Disorders Program, the University of Saskatchewan (USask), and C‐OPN. We included individuals who received DBS surgery in the C‐OPN. Patients included in the C‐OPN cohort are those who have been referred by their academic site to participate in ongoing research initiatives, and therefore does not capture all individuals undergoing DBS at all academic sites across Canada ²⁴ (Table S1). New referrals for DBS to UA from December 2018 to May 2023 formed the “new referrals” cohort. Patients who had DBS implantation (2012–2023) and were actively followed formed the “UA DBS implanted” population. Patients referred for DBS at USask (2016–2023) formed the USask referral group, and those who received DBS implantation at USask (2016 to 2023) formed the USask implanted group. DBS patients enrolled in C‐OPN (June 2020–November 2023) were included. UA patients who were also C‐OPN participants were removed from the C‐OPN cohort so that they were not analyzed twice. USask is not part of C‐OPN. Figure 1, a CONSORT flow diagram showed the groups included and analyzed in the study.

FIG 1.

CONSORT flow diagram for the study groups. The figure showed how the two UA groups (New referral and implanted), two USask groups (New referral and implanted), and C‐OPN DBS patients are included. UA, University of Alberta, USask, University of Saskatchewan; C‐OPN, Canadian Open Parkinson Network, DBS, deep brain stimulation.

The indications of DBS in PD are when motor symptoms cannot be optimized medically, and/or disabling motor complications emerge. The contra‐indications include dementia, untreated depression, and any surgical contra‐indications.

Study Design

For the new referral and implanted groups, a retrospective chart review was performed to collect demographic and clinical information. To compare our patient populations, we used “ethnic” categories set out by Statistics Canada. ²⁵ Data for age, gender, ethnicity, education level, urban versus rural residence, marital status, first spoken language, birth country, and current annual household income bracket were collected and are included in Table 1. Canadian census data defined urban as a minimum population concentration of 1000 people and a population density of 400 persons per square kilometer, while lower densities are defined as rural. ²⁵ Patient‐reported annual household income and number of household dependents were collected. Patients were categorized as above, below, or borderline compared to the 2021 national Low‐Income Cut‐Off (LICO). ²⁵ The mode of referral was documented as primary care physicians, community neurologists, or movement disorders specialists. The LICO data were not collected for the USask and C‐OPN cohorts, and the referral mode was not collected for the C‐OPN cohort.

TABLE 1.

Demographic and clinical information of new referral and implanted group for PD patients at UA Parkinson and Movement Disorders Program, USask Movement Disorders Program, and the C‐OPN group

Demographics	UA new referrals (N = 101)	UA implanted (N = 88)	USask referrals (N = 63)	USask implanted (N = 20)	C‐OPN (N = 43)
Age in years	62.5 (8.5)	62.1 (11.2)	64.9 (9.4)	62.8 (7.5)	66.2 (9.7)	NS
Gender (% man)	63.4	69.3	55.6	45	63.1	NS
MoCA	26.5 (3.1)	27.2 (2.2)	N/A	NS a	25.2 (3.6)	NS
Birth Country
Canada	64 (63.4)	67 (76.1)	60 (95.2)	18 (90)	N/A	*
Marital status
Married	83 (82.2)	71 (80.7)	25 (83.3)	17 (85)	26 (61.9)	*
Place of Residence
Urban	63 (62.4)	56 (63.6)	22 (34.9)	5 (25)	29 (69)	***
Rural	38 (37.6)	32 (36.4)	41 (65.1)	15 (75)	5 (11.9)
Education
<Highschool	34 (38.6)	26 (31.8)	15 (50)	9 (45)	3 (8.8)
College/Trade School	25 (28.7)	30 (36.6)	6 (20)	6 (30)	13 (38.2)
Post‐secondary degree	28 (32.2)	26 (31.7)	9 (30)	5 (25)	18 (52.9)	***
Bachelor's	20 (23)	17 (20.7)	7 (23.3)	5 (25)	10 (29.4)
Graduate degrees	8 (9.2)	9 (11)	2 (6.7)	0	8 (23.5)
Annual household income
<50,000	13 (12.9)	27 (30.7)	9 (30)	7 (35)	N/A	NS
50,000–99,999	26 (25.7)	18 (20.5)	9 (30)	5 (25)	N/A
≥100,000	22 (21.8)	27 (30.68)	8 (26.7)	4 (20)	N/A
Not reported	40 (39.6)	16 (18.2)	33 (52.3)	4 (20)	N/A
Low income cut‐off
Below	3 (2)	11 (12.5)	N/A	N/A	N/A	NS
Borderline	6 (5.9)	8 (9.1)	N/A	N/A	N/A
Mode of referrals (%)
Family physicians	19 (18.8)	9 (10.2)	0	0	NS	*
Subspecialty neurologists	52 (51.5)	61 (69.3)	50 (80.1)	16 (80)	NS
Community neurologists	27 (29.7)	18 (20.5)	13 (19.9)	4 (20)	NS

Note: Bolded p‐values were statistically significant with significance based on $\alpha$ = 0.05. Age is presented as mean (SD), the rest of the data are presented as N (%), excluding the unreported data.

Abbreviations: C‐OPN, Canada Open Parkinson Network; N/A, data not available; NS, not significant; PD, Parkinson's disease; UA, the University of Alberta; USask, the University of Saskatchewan.

^a Neuropsychological testing for the USask implant group revealed 95% had normal or above normal overall cognitive function, with one (5%) had some cognitive impairment query related and beyond language barrier.

^* p < 0.05.

^*** p < 0.001.

Certain parameters (age, gender, and place of residence) were collected via chart review, while all other demographic information (ethnicity, education level, marital status, first spoken language, birth country, and current annual household income) were self‐identified and collected via telephone call. Patients not responding after two calls were coded as “unknown” data and excluded from analysis. UA team (SP &GD) and USask team (EN & BDS) contacted eligible participants from UA and USask, respectively, via phone calls using the same surveys.

Statistical Analysis

Statistical analysis and data visualization were performed on GraphPad Prism (version 10). For comparisons among multiple groups with a continuous variable such as age, a simple ANOVA was used. However, most analyses required comparisons between group proportions, which was achieved using Fisher's exact test and the Chi‐squared test. Chi‐squared was the favored test except for pairwise group proportion comparisons for ethnicity. In this case, the ethnic categories that were not observed and thus represented by a count of zero necessitated the use of Fisher's. Given multiple pair‐wide comparisons Bonferroni multiple‐comparisons correction was done. For ethnicities, the UA groups were compared to the census of Alberta, ²⁵ the USask group was compared to the Saskatchewan census ²⁵ ; while the C‐OPN group were analyzed against the Canadian census. ²⁵ p < 0.05 was considered significant.

Results

For the study duration, there were 101 new PD patients referred for DBS at UA. Eighty‐eight implanted patients were actively followed at UA at the time of data collection (Table 1). Sixty‐three PD patients were referred to USask for DBS between 2016 to 2023. Twenty PD patients received DBS surgery at USask. Forty‐three PD patients were in C‐OPN. Table 1 summarizes the clinical and demographic information of the four groups.

Among all groups, the age was comparable. Men were dominant in all groups except the USask implanted cohort. Gender in the cohorts mostly tracked with the reported male predominance of PD (Men/women = 1.5–2) ²⁶ overall. The ratio of men/women, however, increased from 1.7 for the UA new referrals to 2.3 for the UA implanted group, a 35.3% difference (p = 0.006). Among all groups, 81.8% to 94.1% participants self‐identified as White (Table 1, Fig. 2).

FIG 2.

Ethnicities among patients receiving DBS implants. (A) UA new referrals, (B) UA implanted; (C) USask referrals, (D) USask implanted, and (E) C‐OPN. DBS, deep brain stimulation; UA, University of Alberta; USask, University of Saskatchewan; C‐OPN, Canadian Open Parkinson Network.

The whole cohort analysis in ethnicity showed that 88.1% were White in the implanted patients (p < 0.0001). In Canada, the most recent census showed the following ethnic make‐up: White 68.5%, Asian 17.4%, Indigenous 5%, Latin/Central/South American 2%, Black 4.3%, and Oceanian 0.2% (Table 2). The C‐OPN data does not represent the ethnic distribution (p < 0.001). In Alberta, where most of the data were collected, men make up 50.6% of the population of 4.4 million (2021 data). The total proportion of non‐White people is 34.6% (Table 2). In Edmonton (UA's location) specifically, 36% of people are from a racialized population. Normalized to Alberta data, although there was no statistically significant difference in the UA new referral group (p = 0.06) and the implanted group (p = 0.03) after adjusted for pairwise comparison, the trend was towards White dominant (up to 84.9% in implanted group). We further analyzed the ethnic distribution in the UA program (White 84.5%, South Asia 4%, Chinese 2.5%, Southeast Asia 1.1%, West Asia 0.5%, Japanese 0.5%, Arabian 2%, Latin American 1%, and Indigenous 2.5%). For Saskatchewan, 32% are non‐White, and there are significant Asian (21%) and Indigenous (17.1%) populations. A marked difference was observed in access to DBS where 90% were White (p < 0.0001).

TABLE 2.

Comparison of the ethnic distribution with Canadian and provincial Census.

	Alberta population (%) 22	UA new referral (%), N = 101	UA implanted (%), N = 88	Saskatchewan population (%) 22	USask referral (%), N = 63	USask implanted (%), N = 20	Canadian population (%) 22	C‐OPN (%), N = 43
		p = 0.06	p = 0.03		***	***		***
White	65.4	81.8	84.9	68.5	93.7	90	68.5	94
Indigenous	6.8	0	1.4	17.0	1.6	0	5.0	0
South Asian	7.1	5	9.6	4.1	1.6	5	7.1	0
Chinese	3.9	5	4.1	1.6	1.6	0	4.7	3
Black	4.3	1	0	2.1	0	0	4.3	0
Filipino	5.2	3	4.1	4.0	0	0	2.6	0
Arabian	1.7	3	0	0.5	0	5	1.9	0
Latin American	1.6	1	0	0.5	0	0	1.6	0
Southeast Asian	1.3	0	0	0.8	0	0	1.1	0
West Asian	0.6	0	0	0.3	1.6	0	1.0	0
Korean	0.6	0	0	0.2	0	0	0.6	0
Japanese	0.3	0	1.4	0.1	0	0	0.3	0
Other	1.2	0	1.4	0.5	0	0	1.4	3

Note: Ethnic proportion represented as percentage for breakdown of new referral and implanted group for PD patients at UA Parkinson and Movement Disorders Program, USask Movement Disorders Program, and the C‐OPN group compared to Canadian population data from the 2021 census. UA groups were compared with Alberta data, USask group was compared to Saskatchewan census, and C‐OPN was compared to Canadian census. ¹⁷

Abbreviations: C‐OPN, Canada Open Parkinson Network; PD, Parkinson's disease; UA, the University of Alberta; USask, the University of Saskatchewan.

^*** p < 0.001.

Patients referred and implanted in the study had a higher level of education than the average age‐matched Canadian (Table 1 and Fig. 3A, p < 0.001). Rural residence did not appear to limit access to DBS evaluation or surgery. The relative proportion of implanted patients living in rural versus urban areas was compared to the proportion of Canadians, Albertans, and Saskatchewanians living in those areas respectively ²⁵ ; in fact, when adjusted to the proportion of urban and rural residents, rural residents were overrepresented in the UA (36.4% patients implanted were rural residents, versus 16.4% rural population in Alberta), and USask (75% patients implanted were rural residents, comparing to overall 33.2% rural population in Saskatchewan) (p < 0.001). Marital status was a significant factor. Both referred and implanted patients at UA and USask had a higher rate of being married compared to Canadians in the same age group (Fig. 3B, p = 0.002). In addition, most patients were above the LICO (UA data), and household income did not contribute to the decision to proceed to DBS implantation. More than 50% of referrals were from movement disorders neurologists and these have the highest yield‐when assessing the implanted groups, majority are initially referred by movement disorders neurologists (51.5–90%).

FIG 3.

The highest educational level and marital status of participants. DBS implanted patients showed a higher education level (A), and the proportion of post‐graduate education was significantly higher in those received DBS than the average level of education for Canadians. Marital status in relation to DBS implantations (B). In the UA referral and implanted groups, the USask referral and USask implanted group, patients had a significantly higher rate of being married (***, p < 0.001). The dotted line shows the marital rate of age‐matched Canadian (Ref‐CAN). DBS, deep brain stimulation; UA, University of Alberta; USask, University of Saskatchewan; C‐OPN, Canadian Open Parkinson Network, Ref‐CAN, age‐matched Canadian reference.

The reasons for patients who had been deemed ineligible or declined for DBS were due to cognitive impairment and/or neuropsychiatric concerns (29.7%), non‐motor predominant, speech issues, or balance concerns (14.9%), declining DBS (24.8%), lack of support or social barriers (7.9%). Other reasons included alternative therapies (6.9%), and fears of DBS as an “invasive procedure” (5%). Two patients were lost to follow‐up, and one refused to disclose their reason for declining. Three patients remain approved for surgery on the waitlist. In addition, medication can be further optimized in 7.0% patients and were deemed ineligible. Depending on the clinical situation, referred non‐DBS candidates will be triaged to other device aided therapies, return to community neurologists with optimizing medication, or referred to the interdisciplinary team (geriatrician, psychiatrist, rehabilitation team) accordingly.

Discussion

There is a paucity of evidence for differences in access to DBS related to ethnicity, sex and gender, and more, especially in Canada's public health care system. Further, our data are not limited to specific subpopulations (such as Medicare or Medicaid recipients) and therefore offer a more accurate study of access for the entire eligible population. In this retrospective study, we observed that DBS is under‐utilized in women (except the small cohort from USask) and racialized populations, as seen in previous studies. ³ , ⁴ , ⁶ , ²⁷ The main findings are: (1) Although the referral rate reflected the sex distribution of PD, men were more likely to be implanted; (2) White patients dominated in the referral and the implanted groups; (3) among those receiving DBS, there was a higher level of education and greater likelihood of being married.

Among all groups, UA had the largest dataset. For the UA new referral group, the men/women ratio was 1.7, which is consistent with known disease epidemiology; however, the ratio changed to 2.3 with a 35.3% rise in the implanted group in favor of men. Clinicians and policymakers should pay attention to this significant shift and examine potential root causes for this difference. In movement disorders practice, a gender difference in accessing treatment DBS has been observed, ⁷ , ²⁷ , ²⁸ , ²⁹ and does not align with disease prevalence for many conditions. Several studies identified a gender gap in the referral stage due to referral biases in subspecialty care. ²³ , ³⁰ Although significant work has been done on the influence of sex and gender on health behaviors and outcomes, ³¹ , ³² , ³³ , ³⁴ , ³⁵ , ³⁶ there is less research about how gender and sex influence access to device‐aided therapies, including DBS. In addition, other specialties documented gender referral bias and a lower chance of receiving invasive procedures or device‐aided therapies in women. ³⁷ , ³⁸ , ³⁹

As PD progresses, women are at higher risk than men to develop motor complications, especially dyskinesia. ⁴⁰ , ⁴¹ , ⁴² However, when women receive DBS treatment, they tend to have a longer disease course (later implantation) with worse dyskinesia scores (more severe symptom burden at time of implantation). ³⁰ Patient factors do contribute to this disparity. Potential factors could be how women experience or express their symptoms, including discounting the impact as the product of other untreatable factors such as normal aging rather than their neurologic condition. ⁴³ Women also tend to present later to medical attention with more advanced disease than men. ⁴⁴ , ⁴⁵ In addition, women have different and possibly more disabling nonmotor profiles than men. ²⁸ , ⁴⁶ For example, anxiety is more common among women. ⁴⁷ , ⁴⁸ , ⁴⁹ , ⁵⁰ They may have more difficulties articulating which of their symptoms are most impactful in their daily lives, focusing instead on anxiety or other neurobehavioral complications of their neurologic illness. As a result, physicians may struggle to discern the symptoms most salient to their reduced quality of life, leading to dismissing all their concerns as anxiety rather than searching for clear indications for DBS. This phenomenon may at least partially explain the incongruence of gender ratio from referral to implantation.

Gender differences in health‐related decision‐making also exist. ⁵¹ , ⁵² The overrepresentation of men receiving DBS could in part be due to increased risk‐taking behavior observed in men. Women are more likely to decline DBS referral and assessment, reacting with apprehension and hesitation, and worrying about damage to the brain. Significant delay is evident before women recognized themselves as ill enough to accept the operation's risks, since “they had successively become used to severe symptoms.” ⁵¹ , ⁵³ Gender‐based preferences also exist for delivery of DBS information. Women have strong preference towards peer support and personal stories to help aid decision making, while men preferred numerical data. ⁵¹ , ⁵³ Women tend to express reluctance to DBS due to recovery time and inability to fulfill their role in the household or family business. ⁵²

The gender discrepancy in access to DBS is in direct conflict with the Canada Health Act, ⁸ which has a foundational principle of equitable access to necessary care. In addition, it is an ethical necessity for the clinical team to assure equitable access to such important treatment. Removing systemic barriers and biases to give all individuals equitable opportunity to access and benefit from standard care and to participate in research/clinical trials is essential in health care and health‐related research. ⁵⁴

Our data confirm the ethnic disparity in DBS implantation. ⁶ Patients who were referred and received DBS implantation do not reflect disease prevalence or provincial/national demographics. These observations are consistent with current literature, ⁵ , ⁶ , ⁵⁵ , ⁵⁶ and reflect similar trends in access to device‐aided standard therapies in other areas of medicine. Racialized people are less than half as likely to receive an implantable cardiac defibrillator or defibrillation post cardiac arrest compared to White people. ⁵⁷ , ⁵⁸ For practitioners, altered perception of disability may play a role. Research demonstrates that for PD and tremor, Black patients represented much lower odds (1 in 5) of using DBS, ⁷ and represented <1% of hospital discharges admitted for DBS. ⁶ A Canadian population study documented that among 46,237 PD cases in Ontario, those residing in neighborhoods or postal codes with a predominant racialized population were less likely to receive DBS than patients residing in neighborhoods that are White predominant. ⁵ Similar results exist in Asian, Hispanic, Native Hawaiian and Pacific Islanders. ⁵⁹ , ⁶⁰

Canada as a publicly funded, single‐payer system represents comparable disparities and barriers to countries with similar healthcare systems. For instance, studies in the United Kingdom have also found gender‐based disparities in both uptake and referral, with women being far underrepresented in these spaces compared to men. ³⁰ An ongoing study demonstrates that disparities are common across many publicly‐funded healthcare systems offering DBS, even among high income countries. ⁶¹ In a mixed‐model healthcare system such as that of the United States’, racial disparities are well‐documented, particularly for those utilizing Medicaid. ⁶ While evidence offering direct comparison between systems is limited, one study using the largest nationally representative samples comparing racial inequalities in health in the United States and Canada confirmed racial inequalities in both systems. ⁶² The varying degrees of inequalities and the distinct racial groups impacted suggest that the relationship between race and health is shaped by the societal context in which it unfolds. ⁶²

The prevalence of PD is reported to be lower in Black and Asian people than in White people (1036 vs. 1138 vs. 1672 per 100,000, respectively) ⁶³ ; the difference, however, is not sufficient to account for the observed racial discrepancy in DBS utilization. Some practitioners may consider differences in beliefs and attitudes towards device‐aided therapy, such as DBS, as partially contributing to the racial disparity observed. There are possible differences in the perceptions, attitudes, and articulation of symptoms between racial and ethnic groups or genders. In addition, referral bias in neurologists due to altered perceptions of disability or risk tolerance in certain patient groups can contribute to the currently skewed demographics in DBS recipients. ²⁰ , ⁶⁴ However, a previous study has demonstrated similar perceptions and acceptances of implantable devices among the Black and White patient groups. ⁶⁵ Root causes for disparities in referral and in implantation of DBS must be determined. We observed that patients actively followed in academic centers do not reflect the ethnic distributions in the catchment area. Such skew may also contribute to the disparities to the DBS access. Advocacy and education to engage patients, caregivers, primary care physicians and all stakeholders are necessary.

While past literature has focused on having diverse teams to instill trust in healthcare, ⁶⁶ , ⁶⁷ , ⁶⁸ it is worth noting that the UA DBS physician team is comprised of two South Asian men, one White man, one White woman and two East Asian women. Clearly, our diverse team has not been sufficient to improve equity among our implanted patients.

We observed higher education in the implanted group, and the implanted patients had higher than the average education level among Canadians. This suggests that people with higher education backgrounds had a better chance to receive DBS possibly due to affinity bias. The underlying reasons may be complex. Those with higher socioeconomic status may have higher health literacy, a greater ability to self‐advocate, may treat healthcare teams as peers, therefore develop better rapport, possibly with a stronger trust in science and empiricism. From the healthcare team's perspective, those with higher education are more capable of expressing their distress in ways that are relatable for teams resulting in greater validation and more accurate assessment of illness burden. Another mechanism underlying these findings could also be that a higher education level is associated with positive perceptions of DBS, and in general a better understanding or vocabulary of PD signs and symptoms. ⁶⁹ Together, these pieces point towards patient confidence as a key for self‐advocacy, which may further lead to greater opportunity for tertiary care referrals for these patients. Cultural norms of disclosing suffering may hamper fulsome expression of daily burden resulting in lower assessed symptoms. Similar research in hip or knee osteoarthritis treatment showed that education was significantly associated with high quality decisions. ⁷⁰

Patient demographic characteristics such as language, education, and culture may influence pre‐operative neurological testing. ⁷¹ One study found that Canadian PD patients born in English‐speaking countries performed significantly better on various tests within the battery compared to patients born in non‐English speaking countries. ⁷² Lower patient education level may also influence test performance, representing another barrier to accessing DBS. ⁷³ Furthermore, African American patients experience higher rates of cognitive decline which may further impact DBS eligibility. ⁷³ Clinically, neuropsychological testing is interpreted and compared with age, gender and education matched healthy group, with language barriers taken into consideration. However, clinicians and researchers should always consider the complexity with language and educational barriers in medical decision making.

We also observed that married people had a much higher chance of referral and undergoing surgery, suggesting family support being essential in this complex process. Taking the UA implanted group as an example, among those married, 67.4% are men with caregivers being women. In addition to different non‐motor symptoms and progression between men and women, caregivers have different experiences, expectations, and stressors between men and women. As PD advances, relationships between PD patients and caregivers are enhanced only in those pairs where the caregiver was a woman. ⁷⁴ For example, greater motor impairment in their husbands apparently generated greater empathy and a higher desire to assist the disabled spouse. ⁷⁴ In these dyads, caregivers may describe their role as a gift. Such thought processes may serve as motivation to encourage and engage in DBS workup and to advocate for more intensive treatment for their spouse.

Overall, there are proportionally less people in the rural/remote areas receiving DBS implants. However, when normalized to the population to the urban/rural ratio, people living in the rural area were overrepresented, therefore, residing in rural areas does not limit the access to DBS evaluation or surgery.

Over 50% of DBS referrals came from subspecialty movement disorder neurologists and therefore yielded the highest chance to proceed DBS workup, and receive DBS (>70% in UA and 80% USask). This may reflect barriers in the overall referral process and a fragmentation of care for patients who may be eligible for DBS. Current evidence suggests that this lack of congruence between community and subspecialty neurologists exists in that providers may lack consensus on timing of DBS referral as well as medical management. ⁷⁵ Our data further supports the idea of education for community neurologists and geriatricians as helpful to improve the likelihood of proceeding to implantation and decrease disruptions in the continuum of care for patients.

Finally, we assessed total household income in our study population relative to the LICO, a measure representing an income where 20% more than average of after‐tax income must be spent on food, shelter, and clothing. ⁷⁶ Only UA groups collected LICO. Neither the total household income nor the LICO interfered with referral or implant of DBS. The household income of the USask group also did not influence the DBS implantation. When analyzing these numbers, one needs to consider number of people in the household and area of residence. As our retrospective analysis cannot uncover all details, further comparison is needed. We speculate that equitable access to healthcare plays a role. Further, we include social work assessment to help navigate potential financial challenges for our patients. Additionally, in‐home care is not limited to specific orthopedic procedures or myocardial infarction and is based on need, rather than life expectancy. Patients in Canada would have access to in‐home care for wound care, medication management and in‐home rehabilitation to support them prior to implantation and post‐implantation, as provided by the government.

A limitation of our study includes the small sample size and the fact that the five groups included were heterogeneous, which may limit generalizability of these findings to other contexts. Another limitation to our study is the selection bias introduced by the C‐OPN cohort. In general, research participation may be affected by socioeconomic factors such as education level and income. ⁷⁷ These factors may contribute to an underrepresentation of socioeconomically vulnerable individuals in our study population.

However, the disparity in access to DBS is evident in two centers and the largest Canadian PD registry. In addition, our study has not been able to identify the root causes for such disparities. In future studies, we plan to apply mixed methods to understand the decision‐making pathways of patients, referring physicians and contributing factors affecting referrals to DBS. The qualitative assessment may help gain insights into the factors that may lead to the disparities accessing DBS, and subsequently guide an interventional study to develop culturally sensitive educational material and implement strategies for equitable access to DBS. Furthermore, this study has a focus on patients who are referred for specialized care, but fails to report barriers for patients who are never referred. This represents an important avenue for future qualitative work to explore. This highlights the critical nature of the balance required between community and subspecialty neurology management of PD for patients to best understand their options for device‐aided therapies such as DBS, particularly in the context of Canada's aging population.

Disparities in access to DBS is not an isolated issue in one center or one country. Work and effort are needed in determining the root causes (eg, as demonstrated in COVID‐19 studies—socioeconomic disadvantages, level of education, lifestyle factors, health comorbidities, and limited access to medical care), ⁷⁸ , ⁷⁹ and then proceed with community engagement to improve the discrepancies in access to DBS by including a patient panel, community physicians, and specifically an outreach program to community partners and policy makers.

Author Roles

(1) Research project: A. Conception, B. Organization, C. Execution; (2) Statistical Analysis: A. Design, B. Execution, C. Review and Critique; (3) Manuscript Preparation: A. Writing of the first draft, B. Review and Critique.

F.B.: 1A, 1B, 1C, 2A, 2C, 3A, 3B.

S.P.: 1C, 2B, 3A, 3B.

P.T.: 1C, 2A, 2B, 3B.

K.Y.: 1C, 2C, 3B.

B.D.S.: 1C, 3A, 3B.

E.N.: 1B, 1C, 2C, 3B.

G.D.: 1B, 1C.

S.C.: 1C, 2B, 2C, 3B.

T.S.: 1C, 2A, 2B, 2C, 3B.

A.R.: 1B, 1C, 2C, 3B.

O.M.: 1B, 1C, 2C, 3B.

A.M.V.: 1C, 2C, 3B.

B.S.: 1A, 2C, 3B.

A.S.: 1C, 3B.

J.M.M.: 1A, 1B, 1C, 2A, 2C, 3B.

Disclosures

Ethics Statement: Ethics approvals were granted by the University of Alberta Health Research Ethics Board—Health Panel and the University of Saskatchewan Behavioral Research Ethics Board.

Funding Sources and Conflict of Interest: FB: The current project is supported by the Social Sciences and Humanities Research Council (Grant No. 1036‐2021‐00892) to FB (PI). There was no other funding support for this work. There is no conflict of interest. SP did not receive any funding for the current research. There is no conflict of interest. PT discloses support for this work from Parkinson Foundation Summer Student Fellowship (2023) and 2024 Summer Student Award from Neuroscience Rehabilitation Vision, Strategic Clinical Network of Alberta Health Services. He has no conflict of interest. KY discloses support for this work from Parkinson Canada Clinical Fellowship (2021–2022). There is no conflict of interest. BDS did not receive any funding for the current research. There is no conflict of interest. EN did not receive any funding for the current research. There is no conflict of interest. GD did not receive any funding for the current research. There is no conflict of interest. SC did not receive any funding for the current research. There is no conflict of interest. TS received funding support from the Social Sciences and Humanities Research Council (Grant No. 1036‐2021‐00892) as co‐investigator). There was no other funding support for this work. There is no conflict of interest. AR received funding support from the Social Sciences and Humanities Research Council (Grant No. 1036‐2021‐00892) as co‐investigator. There was no other funding support for this work. There is no conflict of interest. OM received funding support from the Social Sciences and Humanities Research Council (Grant No. 1036‐2021‐00892) as co‐investigator. He also received funding from Parkinson Cananda and Brain Canada as PI for the C‐OPN infrastructure. There was no other funding support for this work. There is no conflict of interest. AMV did not receive any funding for the current research. There is no conflict of interest. BS received funding support from the Social Sciences and Humanities Research Council (Grant No. 1036‐2021‐00892) as co‐investigator. There was no other funding support for this work. There is no conflict of interest. AS did not receive any funding for the current research. There is no conflict of interest. JMM received funding support from the Social Sciences and Humanities Research Council (Grant No. 1036‐2021‐00892) as co‐Director. There was no other funding support for this work. There is no conflict of interest.

Financial Disclosure for the Past 12 Months: FB received Center of Excellence award from Parkinson's Foundation, to Parkinson and Movement Disorders Program, University of Alberta as the Director, the Neurosciences Rehabilitation, and Vision Strategic Clinical Network™ Research Grant as Co‐investigator. Canadian Consortium on Neurodegeneration in Aging (CCNA) CIHR, as site co‐investigator. FB received honorarium from Ipsen as ReACT Working Group consultant. SP declared no disclosures to report. PT declared that there are no additional disclosures to report. KY received honorarium from Abbvie as a guest speaker for continuous medical education regarding dystonia treatment. BDS declared no disclosures to report. EN declared no disclosures to report. GD has no disclosures to report. SC declared no disclosures to report. TS received Canadian Institutes of Health Research Project Grant, Backman Family Fund administered through the University of Alberta Hospital Foundation, speakers honoraria: Abbott Medical, consulting fees: Medtronic, Boston Scientific. AR received unrestricted research support from the Dr. Ali Rajput Endowment for Parkinson's Disease and Movement Disorders, Royal University Hospital Foundation, Saskatoon, SK. OM: Canadian Institutes of Health Research project grant, National Sciences and Engineering Research Council of Canada discovery grant, Université de Montréal and Centre de recherche, institute universitaire de gériatrie de Montréal start‐up funds, Parkinson Canada pilot project grant. AMV: declared no disclosures to report. BS received Canadian Institutes of Health Research project grant, Canadian Institutes of Health Research Tier 1 Chair award, and Canadian Cancer Society—Accelerator Grants. AS: the authors declare that there are no additional disclosures to report. JMM received funding support from University Hospital Foundation (2016–25), Canadian Consortium on Neurodegeneration in Aging (2018‐present), Canadian Open Parkinson Network, Brain Canada (2018–Present). She is Oxford University Press US Delegate 2022–2026, Vice President of American Academy of Neurology (AAN), and Board of Directors of Parkinson Foundation and AAN.

• Ethics approvals were granted by the University of Alberta Health Research Ethics Board—Health Panel and the University of Saskatchewan Behavioral Research Ethics Board, respectively.

• All patients involved in the telephone survey for the demographics of the study provided verbal consent and was documented in the study protocol and record. For the retrospective chart review, since only deidentified patient data were used, informed patient consent was not necessary for this portion of the study.

• We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this work is consistent with those guidelines.

Supporting information

TABLE S1. Recruitment of the PD patients to the C‐OPN cohort by 2023 from each site. The DBS cases recruited are summarized. Number of participants is presented as N (%). C‐OPN, Canada Open Parkinson Network; PD, Parkinson's disease.

Data Availability Statement

The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.