Racial disparities in post-stroke functional outcomes in young patients with ischemic stroke

Racial disparities in functional outcomes following mechanical thrombectomy in a cohort of patients with ischemic stroke

BACKGROUND

Non-Hispanic Black (NHB) patients experience increased prevalence of stroke risk factors and stroke incidence compared with non-Hispanic White (NHW) patients. However, little is known about >90-day post-stroke functional outcomes following mechanical thrombectomy.

OBJECTIVE

To describe patient characteristics, evaluate stroke risk factors, and analyze the adjusted impact of race on long-term functional outcomes to better identify and limit sources of disparity in post-stroke care.

METHODS

We retrospectively reviewed 326 patients with ischemic stroke who underwent thrombectomy at two centers between 2019 and 2022. Race was self-reported as NHB, NHW, or non-Hispanic Other. Stroke risk factors, insurance status, procedural parameters, and post-stroke functional outcomes were collected. Good outcomes were defined as modified Rankin Scale score ≤2 and/or discharge disposition to home/self-care. To assess the impact of race on outcomes at 3-, 6-, and 12-months' follow-up, we performed univariate and multivariate logistic regression.

RESULTS

Patients self-identified as NHB (42%), NHW (53%), or Other (5%). 177 (54.3%) patients were female; the median (IQR) age was 67.5 (59-77) years. The median (IQR) National Institutes of Health Stroke Scale score was 15 (10-20). On univariate analysis, NHB patients were more likely to have poor short- and long-term functional outcomes, which persisted on multivariate analysis as significant at 3 and 6 months but not at 12 months (3 months: OR=2.115, P=0.04; 6 months: OR=2.423, P=0.048; 12 months: OR=2.187, P=0.15). NHB patients were also more likely to be discharged to rehabilitation or hospice/death than NHW patients after adjusting for confounders (OR=1.940, P=0.04).

CONCLUSIONS

NHB patients undergoing thrombectomy for ischemic stroke experience worse 3- and 6-month functional outcomes than NHW patients after adjusting for confounders. Interestingly, this disparity was not detected at 12 months. Future research should focus on identifying social determinants in the short-term post-stroke recovery period to improve parity in stroke care.

Racial disparities in prosthesis abandonment and mobility outcomes after lower limb amputation from a dysvascular etiology in a veteran population

BACKGROUND

Non-Hispanic Black (NHB) individuals have higher rates of amputation and increased risk of a transfemoral amputation due to dysvascular disease than non-Hispanic White (NHW) individuals. However, it is unclear if NHB individuals have differences in prosthesis use or functional outcomes following an amputation.

OBJECTIVE

To determine if there are racial disparities in prosthesis abandonment and mobility outcomes in veterans who have undergone their first major unilateral lower extremity amputation (LEA) due to diabetes and/or peripheral artery disease.

DESIGN

National cohort study that identified individuals retrospectively through the Veterans Affairs (VA) Corporate Data Warehouse (CDW) from March 1, 2018, to November 30, 2020, then prospectively collected their self-reported prosthesis abandonment and mobility. Multiple logistic regression was used to control for potential confounders and identify potential effect modifiers.

SETTING

The VA CDW, participant mailings and phone calls.

PARTICIPANTS

Three hundred fifty-seven individuals who underwent an incident transtibial or transfemoral amputation due to diabetes and/or peripheral arterial disease.

INTERVENTIONS

Not applicable.

MAIN OUTCOMES MEASURES

(1) Self-reported prosthesis abandonment. (2) Level of mobility assessed using the Locomotor Capabilities Index.

RESULTS

Rurally located NHB individuals without a major depressive disorder (MDD) had increased odds of abandoning their prosthesis (adjusted odds ratios [aOR] = 5.3; 95% confidence interval [CI]: [1.3-21.1]). This disparity was nearly three times as large for rurally located NHB individuals with MDD diagnosis, compared with other races from rural areas and with MDD (aOR = 15.8; 95% CI, 2.5-97.6). NHB individuals living in an urban area were significantly less likely to achieve advanced mobility, both with MDD (aOR=0.16; 95% CI: [0.04-7.0]) and without MDD (aOR = 0.26; 95% CI: [0.09-0.73]).

CONCLUSIONS

This study demonstrated that health care disparities persist for NHB veterans following a dysvascular LEA, with increased prosthesis abandonment and worse mobility outcomes.

Racial disparities in access to, and outcomes of, acute ischaemic stroke treatments in the USA

BACKGROUND

Racism contributes to higher comorbid risk factors and barriers to preventive measures for black Americans. Advancements in systems of care, tissue plasminogen activator (tPA) availability and endovascular thrombectomy (ET) have impacted practice and outcomes while outpacing contemporary investigation into acute ischaemic stroke (AIS) care disparities. We examined whether recent data suggest ongoing disparity in AIS interventions and outcomes, and if hospital characteristics affect disparities.

METHODS

We examined 2016-2019 fee-for-service Medicare inpatient data. We ran unadjusted logistic regression models to calculate ORs and 95% CI for two interventions (tPA and ET) and four outcomes (inpatient mortality, 30-day mortality, discharge home and outpatient visit within 30 days), with the main predictor black versus white race, additionally adjusting for demographics, hospital characteristics, stroke severity and comorbidities.

RESULTS

805 181 AIS admissions were analysed (12.4% black, 87.6% white). Compared with white patients, black patients had reduced odds of receiving tPA (OR 0.71, 95% CI 0.69 to 0.74, p<0.0001) and ET (0.69, 95% CI 0.65 to 0.72, p<0.0001). After tPA, black patients had reduced odds of 30-day mortality (0.77, 95% CI 0.72 to 0.82, p<0.0001), discharge home (0.72, 95% CI 0.68 to 0.77, p<0.0001) and outpatient visit within 30 days (0.89, 95% CI 0.84 to 0.95, p=0.0002). After ET, black patients had reduced odds of 30-day mortality (0.71, 95% CI 0.63 to 0.79, p<0.0001) and discharge home (0.75, 95% CI 0.64 to 0.88, p=0.0005). Adjusted models showed little difference in the magnitude, direction or significance of the main effects.

CONCLUSIONS

Black patients were less likely to receive AIS treatments, and if treated had lower likelihood of 30-day mortality, discharge home and outpatient visits. Despite advancements in practice and therapies, racial disparities remain in the modern era of AIS care and are consistent with inequalities previously identified over the last 20 years. The impact of hospital attributes on AIS care disparities warrants further investigation.

Health Care Disparities in Stroke Rehabilitation

Stroke outcomes are influenced by factors such as education, lifestyle, and access to care, which determine the extent of functional recovery. Disparities in stroke rehabilitation research have traditionally included age, race/ethnicity, and sex, but other areas make up a gap in the literature. This article conducted a literature review of original research articles published between 2008 and 2022. The article also expands on research that highlights stroke disparities in risk factors, rehabilitative stroke care, language barriers, outcomes for stroke survivors, and interventions focused on rehabilitative stroke disparities.

Transcranial Doppler ultrasonography can predict inpatient rehabilitation functional outcome in patients with stroke

BACKGROUND

Despite advances in imaging techniques and treatment modalities, tools to predict recovery after stroke remain limited. The objective of the study was to determine if transcranial Doppler (TCD) mean flow velocities were predictive of functional recovery following ischemic stroke.

METHODS

Data were collected from patients with stroke admitted to an academic tertiary care facility in the southeastern region of the United States between 2012 and 2019 who had a middle cerebral artery distribution ischemic stroke, TCD, and were discharged to our inpatient rehabilitation facility. Mean flow velocities were categorized as low (<40 cm/s), normal (40-80 cm/s), or high (>80 cm/s). Functional Independence Measure (FIM) scores were collected on admission to and discharge from IPR. Multiple linear regression models were used to assess the differences in mean FIM score changes by categories of mean flow velocities.

RESULTS

We enrolled 57 patients, mean age 60 years, 73.7% male. Compared to the normal velocity group, those with abnormally low velocities had a significantly smaller change in their FIM score (adjusted β = -8.42; p = .01). Compared to the normal velocity group, those with abnormally high velocities experienced a greater change in FIM score, but this association was not statistically significant (beta = 1.12; p = .77).

CONCLUSIONS

In this limited population, we found that low mean flow velocity as measured by TCD ultrasonography after a middle cerebral artery stroke is associated with poorer functional recovery following inpatient rehabilitation. Our results suggest that the value of TCD ultrasonography as a tool to predict motor recovery after stroke warrants further investigation.

Looking Upstream to Understand Race/Ethnicity as a Moderator for Poststroke Neuroinflammation and a Social Determinant for Poststroke Aphasia Outcomes

INTRODUCTION

Over the past decade, the stroke literature has begun to acknowledge and explore explanations for longstanding racial/ethnic differences in stroke outcomes. Poststroke cognitive impairment (PSCI) and poststroke aphasia are two such negative poststroke outcomes where racial/ethnic differences exist. Physiological differences, such as stroke type and lesion size, have been used to partially explain the variation in PSCI and aphasia. However, there is some evidence, although limited, that suggests neuroinflammatory processes as part of allostatic load may be a key contributor to the observed disparities.

METHOD

In this tutorial, we explore the influence of race differences in inflammation on poststroke cognitive outcomes. We suggest lifetime stress and other external determinants of health such as neighborhood environment and discriminatory practices through "weathering" explain differences in inflammation. While using an allostatic load framework, we explore the literature focusing specifically on the role of neuroinflammation on poststroke outcomes.

CONCLUSIONS

Examination of the immune response poststroke provides a foundation for understanding the mechanisms of PSCI and poststroke aphasia and the potential contributions of neuroinflammatory processes on poststroke cognitive outcomes. Furthermore, understanding of racial differences in those processes may contribute to a better understanding of racial disparities in general stroke outcomes as well as poststroke aphasia.

Outreach for Young Adult African Americans with Risk Factors for Stroke

BACKGROUND

Research suggests that younger adult African American people (age 18-35 years) have more than double the risk of having a stroke than White people. Stroke risk education is lacking for this cohort; there is a dearth of materials that are targeted and focused for young adult African Americans. There is also little research on developing and testing age and culturally appropriate health literate materials that may help this population better understand personal risk factors for stroke.

OBJECTIVE

The aim of this study was to understand factors to guide creating and disseminating plain language health messages about stroke risk awareness among young adult African Americans.

METHODS

African American participants age 18 years and older completed an online survey (N = 413). Descriptive statistics, one-way analysis of variance, and two-step cluster analyses were used to evaluate stroke risk awareness, perceived risk of stroke, message creation factors, and online health information seeking behavior. Open-ended survey items described modifiable and non-modifiable reasons for perceived risk of stroke.

KEY RESULTS

Participants reported differences on overall stroke risk factor awareness by perceived risk of stroke was significant (F[2, 409] = 4.91, p = .008) with the very low/low group (M = 1.66, p < .01), showing significantly lower overall stroke risk factor awareness compared to the moderate and high/very high groups. Both respondents who thought their stroke risk was very low/low and moderate/high/very high commented about family history (54.1% and 45.9%, respectively) as the reason and 88.2% of very low/low commented that they did not have risk factors for stroke because they were young. Cluster analysis indicated the Mostly Clear Preferences cluster was more likely to select mostly/very on positive, informational, and long-term messages and medical authority sources. The largest of three clusters reported medical sources as the highest rated source for both finding and trusting health information (47.2%, n = 195).

CONCLUSION

Young adult African Americans have a scarce understanding of modifiable stroke risk factors; health education materials should focus on positive information messaging that shows a long-term result and is presented by a medical authority. We did not observe any age or sex differences among the data, which suggests different message modalities may not be needed. [HLRP: Health Literacy Research and Practice. 2024;8(1):e38-e46.].

Racial Disparities in Utilization of Emergency Medical Services and Related Impact on Poststroke Disability

BACKGROUND

Prompt seeking of emergency medical services (EMS) assistance at stroke onset is critical to minimize poststroke disability.

OBJECTIVE

The aim was to study how racial differences in EMS decision-relevant factors and EMS use impact stroke care and disability outcomes.

DESIGN

A prospective observational study.

PARTICIPANTS

A total of 1168 acute ischemic stroke patients discharged from April 2016 to October 2017 at a safety net hospital were included; 108 patients were surveyed before discharge.

MEASURES

(1) Prehospital delay: EMS use, timely hospital arrival; (2) Stroke care: alteplase receipt and inpatient rehab; (3) Outcomes: Functional improvement at discharge (admission minus discharge scores on National Institutes of Health Stroke Scale), 90-day modified Rankin Scale; (4) EMS decision-relevant factors: Stroke symptom knowledge, source of knowledge, unfavorable past EMS/care experiences, and financial barriers to EMS use.

RESULTS

Despite more Black patients using EMS than Whites/Asians (56% vs. 48%, P =0.003), their timely hospital arrival was 30% less likely. Adjusted for stroke severity, receipt of alteplase, and inpatient rehab were similar, but Black patients fared worse on functional improvement at discharge (among severe strokes, 2.4 National Institutes of Health Stroke Scale points less improvement, P <0.01), and on functional normalcy at 90 days (modified Rankin Scale score 0-1 being 60% less likely across severity categories) ( P <0.01). Fewer Black patients knew any stroke symptoms before the stroke (72% vs. 87%, P =0.03), and fewer learned about stroke from providers ( P =0.01). Financial barriers and provider mistrust were similar.

CONCLUSIONS

Black patients had less knowledge of stroke symptoms, more care-seeking delay, and poorer outcomes. Including stroke education as a standard of chronic disease care may mitigate stroke outcome disparities.

Was COVID-19 Associated With Worsening Inequities in Stroke Treatment and Outcomes?

Background COVID-19 stressed hospitals and may have disproportionately affected the stroke outcomes and treatment of Black and Hispanic individuals. Methods and Results This retrospective study used 100% Medicare Provider Analysis and Review file data from between 2016 and 2020. We used interrupted time series analyses to examine whether the COVID-19 pandemic exacerbated disparities in stroke outcomes and reperfusion therapy. Among 1 142 560 hospitalizations for acute ischemic strokes, 90 912 (8.0%) were Hispanic individuals; 162 752 (14.2%) were non-Hispanic Black individuals; and 888 896 (77.8%) were non-Hispanic White individuals. The adjusted odds of mortality increased by 51% (adjusted odds ratio [aOR], 1.51 [95% CI, 1.34-1.69]; P<0.001), whereas the rates of nonhome discharges decreased by 11% (aOR, 0.89 [95% CI, 0.82-0.96]; P=0.003) for patients hospitalized during weeks when the hospital's proportion of patients with COVID-19 was >30%. The overall rates of motor deficits (P=0.25) did not increase, and the rates of reperfusion therapy did not decrease as the weekly COVID-19 burden increased. Black patients had lower 30-day mortality (aOR, 0.70 [95% CI, 0.69-0.72]; P<0.001) but higher rates of motor deficits (aOR, 1.14 [95% CI, 1.12-1.16]; P<0.001) than White individuals. Hispanic patients had lower 30-day mortality and similar rates of motor deficits compared with White individuals. There was no differential increase in adverse outcomes or reduction in reperfusion therapy among Black and Hispanic individuals compared with White individuals as the weekly COVID-19 burden increased. Conclusions This national study of Medicare patients found no evidence that the hospital COVID-19 burden exacerbated disparities in treatment and outcomes for Black and Hispanic individuals admitted with an acute ischemic stroke.

Stroke in Young Adults

Stroke in young adults is associated with significant morbidity, and its prevalence is rising in the United States. This is partly attributed to a rise in the prevalence of traditional risk factors including hypertension, hypercholesterolemia, obesity, diabetes mellitus, smoking and heart disease. In addition, there are non-modifiable risk factors comprising migraine, pregnancy and postpartum state, illicit drug use, oral contraceptives and hypercoagulable state. The mechanisms causing stroke in young adults are unique and include cervical dissection, cardioembolic phenomenon, vasculitis and vasculopathy, connective tissue disease, patent foramen ovale and cerebral venous thrombosis. The diagnosis of stroke in the young population can be challenging given its myriad clinical presentations. In this document, we provide an overview of the epidemiology of stroke in young adults, explore mechanisms that may explain increasing rates of stroke in this population, and provide a critical updated overview of the existing literature on the management and prevention of stroke in young adults.

Evidence-Based Disparities in Stroke Care Metrics and Outcomes in the United States: A Systematic Review

Stroke disproportionately affects racial minorities, and the level to which stroke treatment practices differ across races is understudied. Here, we performed a systematic review of disparities in stroke treatment between racial minorities and White patients. A systematic literature search was performed on PubMed to identify studies published from January 1, 2010, to April 5, 2021 that investigated disparities in access to stroke treatment between racial minorities and White patients. A total of 30 studies were included in the systematic review. White patients were estimated to use emergency medical services at a greater rate (59.8%) than African American (55.6%), Asian (54.7%), and Hispanic patients (53.2%). A greater proportion of White patients (37.4%) were estimated to arrive within 3 hours from onset of stroke symptoms than African American (26.0%) and Hispanic (28.9%) patients. A greater proportion of White patients (2.8%) were estimated to receive tPA (tissue-type plasminogen activator) as compared with African American (2.3%), Hispanic (2.6%), and Asian (2.3%) patients. Rates of utilization of mechanical thrombectomy were also lower in minorities than in the White population. As shown in this review, racial disparities exist at key points along the continuum of stroke care from onset of stroke symptoms to treatment. Beyond patient level factors, these disparities may be attributed to other provider and system level factors within the health care ecosystem.

Sex is a defining feature of neuroimaging phenotypes in major brain disorders

Sex is a biological variable that contributes to individual variability in brain structure and behavior. Neuroimaging studies of population-based samples have identified normative differences in brain structure between males and females, many of which are exacerbated in psychiatric and neurological conditions. Still, sex differences in MRI outcomes are understudied, particularly in clinical samples with known sex differences in disease risk, prevalence, and expression of clinical symptoms. Here we review the existing literature on sex differences in adult brain structure in normative samples and in 14 distinct psychiatric and neurological disorders. We discuss commonalities and sources of variance in study designs, analysis procedures, disease subtype effects, and the impact of these factors on MRI interpretation. Lastly, we identify key problems in the neuroimaging literature on sex differences and offer potential recommendations to address current barriers and optimize rigor and reproducibility. In particular, we emphasize the importance of large-scale neuroimaging initiatives such as the Enhancing NeuroImaging Genetics through Meta-Analyses consortium, the UK Biobank, Human Connectome Project, and others to provide unprecedented power to evaluate sex-specific phenotypes in major brain diseases.

A Contemporary Review of Epidemiology, Risk Factors, Etiology, and Outcomes of Premature Stroke

PURPOSE OF REVIEW

Recent data identifies increases in young ischemic and hemorrhagic strokes. We provide a contemporary overview of current literature on stroke among young patients or premature stroke along with directions for future investigation.

RECENT FINDINGS

Strokes in the young are highly heterogenous and often cryptogenic. Sex distribution and risk factors shift from women among the youngest age groups (< 35) to men over the age of 45, with a coinciding rise in traditional vascular risk factors. Incidence is higher in minority and socioeconomically disadvantaged populations, and the impact of stroke among these communities may be exaggerated by disparities in symptom recognition and access to care. Special diagnostic work-up may be needed, and a lower threshold for diagnosis is warranted as potential misdiagnosis is a concern and may preclude necessary triage and management. Although "premature strokes" form a relatively small proportion of total incidence, they vary greatly across subgroups and present an outsized impact on quality of life and productivity.

Effect of Hispanic Status in Mechanical Thrombectomy Outcomes After Ischemic Stroke: Insights From STAR

Background and Purpose

Epidemiological studies have shown racial and ethnic minorities to have higher stroke risk and worse outcomes than non-Hispanic Whites. In this cohort study, we analyzed the STAR (Stroke Thrombectomy and Aneurysm Registry) database, a multi-institutional database of patients who underwent mechanical thrombectomy for acute large vessel occlusion stroke to determine the relationship between mechanical thrombectomy outcomes and race.

Methods

Patients who underwent mechanical thrombectomy between January 2017 and May 2020 were analyzed. Data included baseline characteristics, vascular risk factors, complications, and long-term outcomes. Functional outcomes were assessed with respect to Hispanic status delineated as non-Hispanic White (NHW), non-Hispanic Black (NHB), or Hispanic patients. Multivariate analysis was performed to identify variables associated with unfavorable outcome or modified Rankin Scale ≥3 at 90 days.

Results

Records of 2115 patients from the registry were analyzed. Median age of Hispanic patients undergoing mechanical thrombectomy was 60 years (72–84), compared with 63 years (54–74) for NHB, and 71 years (60–80) for NHW patients (P<0.001). Hispanic patients had a higher incidence of diabetes (41%; P<0.001) and hypertension (82%; P<0.001) compared with NHW and NHB patients. Median procedure time was shorter in Hispanics (36 minutes) compared to NHB (39 minutes) and NHW (44 minutes) patients (P<0.001). In multivariate analysis, Hispanic patients were less likely to have favorable outcome (odds ratio, 0.502 [95% CI, 0.263–0.959]), controlling for other significant predictors (age, admission National Institutes Health Stroke Scale, onset to groin time, number of attempts, procedure time).

Conclusions

Hispanic patients are less likely to have favorable outcome at 90 days following mechanical thrombectomy compared to NHW or NHB patients. Further prospective studies are required to validate our findings.

A Predictive Model for Functional Outcome in Patients with Acute Ischemic Stroke Undergoing Endovascular Thrombectomy

INTRODUCTION

Endovascular thrombectomy (EVT) is a well-established treatment of acute ischemic stroke. Variability in outcomes among thrombectomy patients results in a need for patient centered approaches to recovery. Identifying key factors that are associated with outcomes can help prognosticate and direct resources for continued improvement post-treatment. Thus, we developed a comprehensive predictive model of short-term outcomes post-thrombectomy.

METHODS

This is a retrospective chart review of adult patients who underwent EVT at our institution over the last four years. Primary outcome was dichotomized 90-day mRS (mRS 0-2 v mRS 3-6). Bivariate analyses were conducted, followed by logistic regression modelling via a backward-elimination approach to identify the best fit predictive model.

RESULTS

326 thrombectomies were performed; 230 cases were included in the model. In the final predictive model, adjusting for age, gender, race, diabetes, and presenting NIHSS, pre-admission mRS = 0-2 (OR 18.1; 95% 3.44-95.48; p < 0.001) was the strongest predictor of a good outcome at 90-days. Other independent predictors of good outcomes included being a non-smoker (OR 5.4; 95% CI 1.53-19.00; p = 0.01) and having a post-thrombectomy NIHSS<10 (OR 9.7; 95% CI 3.90-24.27; p < 0.001). A decompressive hemicraniectomy (DHC) was predictive of a poor outcome at 90-days (OR 0.07; 95% CI 0.01-0.72; p = 0.03). This model had a Sensitivity of 79%, a Specificity of 89% and an AUC=0.89.

CONCLUSION

Our model identified low pre-admission mRS score, low post-thrombectomy NIHSS, non-smoker status and not requiring a DHC as predictors of good functional outcomes at 90-days. Future works include developing a prognostic scoring system.

Obstructive sleep apnea and stroke severity: Impact of clinical risk factors

BACKGROUND

Specific clinical and demographic risk factors may be associated with improving or worsening neurologic outcomes within a population of acute ischemic stroke (AIS) patients with a history of obstructive sleep apnea (OSA). The objective of this study was to determine the changes in neurologic outcome during a 14-day recovery as it relates to initial stroke severity in AIS patients with OSA.

METHODS

This retrospective study analyzed baseline clinical risk factors and demographic data collected in a regional stroke center from January 2010 to June 2016. Our primary endpoint measure was the National Institutes of Health Stroke Scale (NIHSS) score and our secondary endpoint measures included the clinical factors associated with improving (NIHSS score ≤7) or worsening (NIHSS score >7) neurological outcome. The relative contribution of each variable to stroke severity and related outcome was determined using a logistic regression. The regression models were checked for the overall correct classification percentage using a Hosmer-Lemeshow test, and the sensitivity of our models was determined by the area under the receiver operating characteristic curve.

RESULTS

A total of 5469 AIS patients were identified. Of this, 96.89% did not present with OSA while 3.11% of AIS patients presented with OSA. Adjusted multivariate analysis demonstrated that in the AIS population with OSA, atrial fibrillation (AF) (odds ratio [OR] = 3.36, 95% confidence interval [CI], 1.289-8.762, P = 0.013) and changes in ambulatory status (OR = 2.813, 95% CI, 1.123-7.041, P = 0.027) showed an association with NIHSS score >7 while being Caucasian (OR = 0.214, 95% CI, 0.06-0.767, P = 0.018) was associated with NIHSS score ≤7.

CONCLUSION

In AIS patients with OSA, AF and changes in ambulatory status were associated with worsening neurological outcome while Caucasian patients were associated with improving neurological outcome. Our findings may have significant implications for patient stratification when determining treatment protocols with respect to neurologic outcomes in AIS patients with OSA.