Social Risk and Dialysis Facility Performance in the First Year of the ESRD Treatment Choices Model.

Importance: The End-Stage Renal Disease Treatment Choices (ETC) model randomly selected 30% of US dialysis facilities to receive financial incentives based on their use of home dialysis, kidney transplant waitlisting, or transplant receipt. Facilities that disproportionately serve populations with high social risk have a lower use of home dialysis and kidney transplant raising concerns that these sites may fare poorly in the payment model. Objective: To examine first-year ETC model performance scores and financial penalties across dialysis facilities, stratified by their incident patients' social risk. Design, Setting, and Participants: A cross-sectional study of 2191 US dialysis facilities that participated in the ETC model from January 1 through December 31, 2021. Exposure: Composition of incident patient population, characterized by the proportion of patients who were non-Hispanic Black, Hispanic, living in a highly disadvantaged neighborhood, uninsured, or covered by Medicaid at dialysis initiation. A facility-level composite social risk score assessed whether each facility was in the highest quintile of having 0, 1, or at least 2 of these characteristics. Main Outcomes and Measures: Use of home dialysis, waitlisting, or transplant; model performance score; and financial penalization. Results: Using data from 125 984 incident patients (median age, 65 years [IQR, 54-74]; 41.8% female; 28.6% Black; 11.7% Hispanic), 1071 dialysis facilities (48.9%) had no social risk features, and 491 (22.4%) had 2 or more. In the first year of the ETC model, compared with those with no social risk features, dialysis facilities with 2 or more had lower mean performance scores (3.4 vs 3.6, P = .002) and lower use of home dialysis (14.1% vs 16.0%, P < .001). These facilities had higher receipt of financial penalties (18.5% vs 11.5%, P < .001), more frequently had the highest payment cut of 5% (2.4% vs 0.7%; P = .003), and were less likely to achieve the highest bonus of 4% (0% vs 2.7%; P < .001). Compared with all other facilities, those in the highest quintile of treating uninsured patients or those covered by Medicaid experienced more financial penalties (17.4% vs 12.9%, P = .01) as did those in the highest quintile in the proportion of patients who were Black (18.5% vs 12.6%, P = .001). Conclusions: In the first year of the Centers for Medicare & Medicaid Services' ETC model, dialysis facilities serving higher proportions of patients with social risk features had lower performance scores and experienced markedly higher receipt of financial penalties.

Structural Racism, Historical Redlining, and Incidence of Kidney Failure in US Cities, 2012-2019.

SIGNIFICANCE STATEMENT: Residing in neighborhoods designated as grade D (hazardous) by the Home Owners' Loan Corporation (HOLC) under historical redlining-a discriminatory housing policy beginning in the 1930s-has been associated with present-day adverse health outcomes such as diabetes mortality. Historical redlining might underlie conditions in present-day neighborhoods that contribute to inequitable rates of kidney failure incidence, particularly for Black individuals, but its association with kidney disease is unknown. The authors found that among adults with incident kidney failure living in 141 metropolitan areas, residence in a historically redlined neighborhood rated grade D was associated with significantly higher kidney failure incidence rates compared with residence in a redlined grade A (best) neighborhood. These findings suggest that historical racist policies continue to affect current-day racial inequities in kidney health. BACKGROUND: Historical redlining was a 1930s federally sponsored housing policy that permitted the Home Owners' Loan Corporation (HOLC) to develop color-coded maps and grade neighborhoods' mortgage lending risk on the basis of characteristics that included racial makeup. This practice has been associated with present-day health disparities. Racial inequities in kidney disease-particularly for Black individuals-have been linked to residential segregation and other structural inequities. METHODS: Using a registry of people with incident kidney failure and digitized HOLC maps, we examined the association between residence in a historically redlined US census tract (CT) with a historical HOLC grade of D or hazardous) and present-day annual CT-level incidence of kidney failure incidence among adults in 141 US metropolitan areas, in 2012 through 2019. RESULTS: Age-adjusted and sex-adjusted kidney failure incidence rates were significantly higher in CTs with a historical HOLC grade D compared with CTs with a historical HOLC grade of A or best (mean, 740.7 per million versus 326.5 per million, respectively, a difference of 414.1 per million). Compared with national averages of all adults in our sample, rates of kidney failure incidence were higher for Black adults in our study sample, irrespective of CT HOLC grade. Age-adjusted and sex-adjusted incidence rates for Black persons in CTs with a HOLC grade D were significantly higher than for Black persons residing in HOLC grade A CTs (mean, 1227.1 per million versus 1030.5 per million, respectively [a difference of 196.6 per million]). CONCLUSIONS: Historical redlining is associated with present-day disparities in kidney failure incidence, demonstrating the legacy of historical racist policies on contemporary racial inequities in kidney health. PODCAST: This article contains a podcast at https://dts.podtrac.com/redirect.mp3/www.asn-online.org/media/podcast/JASN/2023_08_24_JASN0000000000000165.mp3.

Centralizing Telehealth Test-to-Treat Through a Regional Clinical Contact Center: A Veterans Health Administration Pilot.

Background: This project describes a Veterans Health Administration telehealth pilot to facilitate COVID-19 oral antiviral treatment as part of the national test-to-treat (T2T) strategy. The pilot was operationalized for two pilot VA medical centers by the regional clinical contact center (CCC) for a Veteran Integrated Service Network, which offers multiple services through several virtual modalities. Methods: Nurse triage and medical provider evaluation templates were developed for the CCC to standardize clinical interventions with veteran callers reporting positive home COVID-19 test results. When veterans were determined eligible and consented to treatment with an emergency use authorization (EUA) antiviral medication, CCC providers used secure direct messaging for synchronous communication with local pharmacy services to facilitate adjudication and dispensing. Templates for pharmacy documentation and primary care follow-up monitoring were also developed and disseminated. Results: In total, 198 veterans (mean age 65 years, 89% male, 88% non-Hispanic White) were evaluated through telehealth by regional CCC providers using the T2T process and 96% were prescribed an antiviral medication. Primary care follow-up occurred in 86% of cases, a median of 3 days after the telehealth evaluation. The 30-day all-cause hospitalization rate was 1.5% and there were no deaths within 30 days of treatment initiation. Conclusions: Veterans Integrated Service Network's CCC telehealth triage and evaluation processes enabled safe EUA-compliant care delivery, improved evaluator experience and efficiency, and augmented existing EUA processes in place by front-line pharmacy and primary care teams.

Medicaid Expansion and Medicare-Financed Hospitalizations Among Adult Patients With Incident Kidney Failure.

Importance: Although Medicare provides health insurance coverage for most patients with kidney failure in the US, Medicare beneficiaries who initiate dialysis without supplemental coverage are exposed to substantial out-of-pocket costs. The availability of expanded Medicaid coverage under the Patient Protection and Affordable Care Act (ACA) for adults with kidney failure may improve access to care and reduce Medicare-financed hospitalizations after dialysis initiation. Objective: To examine the implications of the ACA's Medicaid expansion for Medicare-financed hospitalizations, health insurance coverage, and predialysis nephrology care among Medicare-covered adults aged 19 to 64 years with incident kidney failure in the first year after initiating dialysis. Design, Setting, and Participants: This cross-sectional study used a difference-in-differences approach to assess Medicare-financed hospitalizations among adults aged 19 to 64 years who initiated dialysis between January 1, 2010, and December 31, 2018, while covered by Medicare Part A (up to 5 years postexpansion). Data on patients were obtained from the Renal Management Information System's End Stage Renal Disease Medical Evidence Report, which includes data for all patients initiating outpatient maintenance dialysis regardless of health insurance coverage, treatment modality, or citizenship status, and these data were linked with claims data from the Medicare Provider Analysis and Review. Data were analyzed from January to August 2022. Exposure: Living in a Medicaid expansion state. Main Outcomes and Measures: Primary outcomes were number of Medicare-financed hospitalizations and hospital days in the first 3 months, 6 months, and 12 months after dialysis initiation. Secondary outcomes included dual Medicare and Medicaid coverage at 91 days after dialysis initiation and the presence of an arteriovenous fistula or graft at dialysis initiation for patients undergoing hemodialysis. Results: The study population included 188 671 adults, with 97 071 living in Medicaid expansion states (mean [SD] age, 53.4 [9.4] years; 58 329 men [60.1%]) and 91 600 living in nonexpansion states (mean [SD] age, 53.0 [9.6] years; 52 677 men [57.5%]). In the first 3 months after dialysis initiation, Medicaid expansion was associated with a significant decrease in Medicare-financed hospitalizations (-4.24 [95% CI, -6.70 to -1.78] admissions per 100 patient-years; P = .001) and hospital days (-0.73 [95% CI, -1.08 to -0.39] days per patient-year; P < .001), relative reductions of 8% for both outcomes. Medicaid expansion was associated with a 2.58-percentage point (95% CI, 0.88-4.28 percentage points; P = .004) increase in dual Medicare and Medicaid coverage at 91 days after dialysis initiation and a 1.65-percentage point (95% CI, 0.31-3.00 percentage points; P = .02) increase in arteriovenous fistula or graft at initiation. Conclusions and Relevance: In this cross-sectional study with a difference-in-differences analysis, the ACA's Medicaid expansion was associated with decreases in Medicare-financed hospitalizations and hospital days and increases in dual Medicare and Medicaid coverage. These findings suggest favorable spillover outcomes of Medicaid expansion to Medicare-financed care, which is the primary payer for patients with kidney failure.

Changes in Migration and Mortality Among Patients With Kidney Failure in Puerto Rico After Hurricane Maria.

Importance: On September 20, 2017, one of the most destructive hurricanes in US history made landfall in Puerto Rico. Anecdotal reports suggest that many persons with kidney failure left Puerto Rico after Hurricane Maria; however, empirical estimates of migration and health outcomes for this population are scarce. Objective: To assess the changes in migration and mortality among patients with kidney failure in need of dialysis treatment in Puerto Rico after Hurricane Maria. Design, Setting, and Participants: This cross-sectional study used an interrupted time-series design of 6-month mortality rates and migration of 11 652 patients who received hemodialysis or peritoneal dialysis care in Puerto Rico before Hurricane Maria (before October 1, 2017) and/or during and after Hurricane Maria (on/after October 1, 2017). Data analyses were performed from February 12, 2019, to June 16, 2022.. Main Outcomes and Measures: Number of unique persons dialyzed in Puerto Rico per quarter; receipt of dialysis treatment outside Puerto Rico per quarter; and 6-month mortality rate per person-quarter for all persons undergoing dialysis. Exposures: Hurricane Maria. Results: The entire study sample comprised 11 652 unique persons (mean [SD] age, 59 [14.7] years; 7157 [61.6%] men and 4465 [38.4%] women; 10 675 [91.9%] Hispanic individuals). There were 9022 patients with kidney failure and dialysis treatment before and 5397 patients after Hurricane Maria. Before the hurricane, the mean quarterly number of unique persons dialyzed in Puerto Rico was 2834 per quarter (95% CI, 2771-2897); afterwards it dropped to 261 (95% CI, -348 to -175; relative change, 9.2%). The percentage of persons who had 1 or more dialysis sessions outside of Puerto Rico in the next quarter following a previous dialysis in Puerto Rico was 7.1% before Hurricane Maria (95% CI, 4.8 to 9.3). There was a significant increase of 5.8 percentage points immediately after the hurricane (95% CI, 2.7 to 9.0). The 6-month mortality rate per person-quarter was 0.08 (95% CI, 0.08 to 0.09), and there was a nonsignificant increase in level of mortality rates and a nonsignificant decreasing trend in mortality rates. Conclusions and Relevance: The findings of this cross-sectional study suggest there was a significant increase in the number of people receiving dialysis outside of Puerto Rico after Hurricane Maria. However, no significant differences in mortality rates before and after the hurricane were found, which may reflect disaster emergency preparedness among dialysis facilities and the population with kidney failure, as well as efforts from other stakeholders.

County-Level Dialysis Facility Supply and Distance Traveled to Facilities among Incident Kidney Failure Patients.

Background: The availability of dialysis facilities and distance traveled to receive care can impact health outcomes for patients with newly onset kidney failure. We examined recent changes in county-level number of dialysis facilities between 2012 and 2019 and assessed the association between county-level dialysis facility supply and the distance incident kidney failure patients travel to receive care. Methods: We conducted a cross-sectional study of 828,427 adult patients initiating in-center hemodialysis for incident kidney failure between January 1, 2012, and December 31, 2019. We calculated the annual county-level number of dialysis facilities, and counties were categorized as having zero, one, two, or three or more dialysis facilities at the time of treatment initiation. We then measured the distance traveled between a patient's home address and dialysis facility at treatment initiation (in miles) and evaluated the association between county-level number of dialysis facilities and distance traveled to initiate treatment. Results: The average annual county-level number of facilities increased from 1.8 to 2.3 between 2012 and 2019. In our study period, 5% of incident adult kidney failure patients resided in a county that had zero dialysis facilities between 2012 and 2019. Compared with counties with three or more dialysis facilities, patients living in counties with no facilities in our study period traveled 14.3 miles (95% CI, 13.4 to 15.2) further for treatment. Conclusions: Kidney failure patients in counties that had no dialysis facilities traveled further, limiting their access to dialysis. Counties with no dialysis facilities at the end of the study period were more rural and had higher poverty than other counties.

Treatment Patterns and Characteristics of Dialysis Facilities Randomly Assigned to the Medicare End-Stage Renal Disease Treatment Choices Model.

Importance: In 2021, Medicare launched the End-Stage Renal Disease Treatment Choices (ETC) model, which randomly assigned approximately 30% of dialysis facilities to new financial incentives to increase use of transplantation and home dialysis; these financial bonuses and penalties are calculated by comparing living-donor transplantation, transplant wait-listing, and home dialysis use in ETC-assigned facilities vs benchmarks from non-ETC-assigned (ie, control) facilities. Because model participation is randomly assigned, evaluators may attribute any downstream differences in outcomes to facility performance rather than any imbalance in baseline characteristics. Objective: To identify preintervention imbalances in dialysis facility characteristics that should be recognized in any ETC model evaluations. Design, Setting, and Participants: This cross-sectional study compared ETC-assigned and control dialysis facility characteristics in the United States from 2017 to 2018. A total of 6062 facilities were included. Data were analyzed from February 2021 to May 2022. Exposures: Assignment to the ETC model. Main Outcomes and Measures: Dialysis facilities' preintervention transplantations and home dialysis use, facility characteristics (notably, profit and chain status), patient demographic characteristics, and community socioeconomic characteristics. Results: Among 316 927 patients, with 6 178 855 attributed patient-months, the mean (SD) age in January 2017 was 59 (11) years, and 132 462 (42%) were female. Patients in ETC-assigned facilities had 9% (0.2 [95% CI, 0.1-0.2] percentage points) lower prevalence of living donor transplantation, 12% (3.2 [95% CI, 3.0-3.3] percentage points) lower prevalence of transplantation wait-listing, and 4% (0.4 [95% CI, 0.3-0.4] percentage points) lower prevalence of peritoneal dialysis use compared with control facilities. ETC-assigned facilities were 14% (5.1 [95% CI, 0.9-9.4] percentage points) more likely than control facilities to be owned by the second largest dialysis organization. Relative to control facilities, ETC-assigned facilities also treated 34% (6.6 [95% CI, 6.5-6.7] percentage point) fewer patients with Hispanic ethnicity and were located in communities with median household incomes that were 4% ($2500; 95% CI, $500-$4500) lower on average. Conclusions and Relevance: In this study, dialysis facilities in ETC-assigned regions had lower preintervention prevalence of transplantation wait-listing, living donor transplantation, and peritoneal dialysis use, relative to control facilities. ETC-assigned and control facilities also differed with respect to other facility, patient, and community characteristics. Evaluators should account for these preintervention imbalances to minimize bias in their inferences about the model's association with postintervention outcomes.

Comparison of mortality between Medicare Advantage and traditional Medicare beneficiaries with kidney failure.

OBJECTIVES: To compare risk-adjusted 1-year mortality between Medicare Advantage (MA) and traditional Medicare (TM) enrollees with kidney failure who initiated dialysis. STUDY DESIGN: Longitudinal analysis of mortality and enrollment data for Medicare beneficiaries. METHODS: The study compared mortality between MA and TM enrollees with kidney failure who initiated dialysis in 2016, accounting for their enrollment switches between MA and TM during 12 months prior to dialysis initiation. Analyses were adjusted for risk scores and fixed effects for the month of dialysis initiation and county of residence. RESULTS: The difference in risk-adjusted 1-year mortality between MA stayers (Medicare beneficiaries who were continuously enrolled in MA prior to dialysis initiation) and TM stayers (those who were continuously enrolled in TM prior to initiating dialysis) was -0.1 percentage points (95% CI, -1.0 to 0.8); however, the difference increased to -1.0 percentage points (95% CI, -3.2 to 1.2) when comparing TM-to-MA switchers (those who switched from TM to MA before initiation) with TM stayers, a comparison more prone to favorable selection bias given our finding that TM-to-MA switchers were healthier than MA stayers. CONCLUSIONS: Among Medicare beneficiaries with kidney failure who initiated dialysis, risk-adjusted 1-year mortality rate is not different between MA and TM stayers. If there is remaining favorable selection in MA due to unobserved health status, our finding provides a lower-bound estimate of the MA impact on mortality among beneficiaries with kidney failure.

Despite National Declines In Kidney Failure Incidence, Disparities Widened Between Low- And High-Poverty US Counties.

National estimates suggest that kidney failure incidence is declining in the US. However, whether this trend is evident in areas with socioeconomic disadvantage is unknown. We examined trends in kidney failure incidence by county-level poverty between 2000 and 2017 and divided the study period into period 1 (2000-05), period 2 (2006-11), and period 3 (2012-17). The magnitude of disparity in kidney failure incidence between high- and low-poverty counties increased from 42.8 more incident cases per million in high-poverty counties in period 1 to 100.1 more in period 3. Despite a national decline, kidney failure incidence increased in high-poverty counties, and disparities between high- and low-poverty counties widened from 2000 to 2017. Achieving the Department of Health and Human Services objective of reducing incident kidney failure cases by 25 percent by 2030 will require focused attention on preventing kidney failure in counties with higher poverty.

Evaluation of Racial, Ethnic, and Socioeconomic Disparities in Initiation of Kidney Failure Treatment During the First 4 Months of the COVID-19 Pandemic.

Importance: Persons with kidney failure require treatment (ie, dialysis or transplantation) for survival. The burden of the COVID-19 pandemic and pandemic-related disruptions in care have disproportionately affected racial and ethnic minority and socially disadvantaged populations, raising the importance of understanding disparities in treatment initiation for kidney failure during the pandemic. Objective: To examine changes in the number and demographic characteristics of patients initiating treatment for incident kidney failure following the COVID-19 pandemic by race and ethnicity, county-level COVID-19 mortality rate, and neighborhood-level social disadvantage. Design, Setting, and Participants: This cross-sectional time-trend study used data from US patients who developed kidney failure between January 1, 2018, and June 30, 2020. Data were analyzed between January and July 2021. Exposures: COVID-19 pandemic. Main Outcomes and Measures: Number of patients initiating treatment for incident kidney failure and mean estimated glomerular filtration rate (eGFR) at treatment initiation. Results: The study population included 127 149 patients with incident kidney failure between January 1, 2018, and June 30, 2020 (mean [SD] age, 62.8 [15.3] years; 53 021 [41.7%] female, 32 932 [25.9%] non-Hispanic Black, and 19 835 [15.6%] Hispanic/Latino patients). Compared with the pre-COVID-19 period, in the first 4 months of the pandemic (ie, March 1 through June 30, 2020), there were significant decreases in the proportion of patients with incident kidney failure receiving preemptive transplantation (1805 [2.1%] pre-COVID-19 vs 551 [1.4%] during COVID-19; P < .001) and initiating hemodialysis treatment with an arteriovenous fistula (2430 [15.8%] pre-COVID-19 vs 914 [13.4%] during COVID-19; P < .001). The mean (SD) eGFR at initiation declined from 9.6 (5.0) mL/min/1.73 m2 to 9.5 (4.9) mL/min/1.73 m2 during the pandemic (P < .001). In stratified analyses by race/ethnicity, these declines were exclusively observed among non-Hispanic Black patients (mean [SD] eGFR: 8.4 [4.6] mL/min/1.73 m2 pre-COVID-19 vs 8.1 [4.5] mL/min/1.73 m2 during COVID-19; P < .001). There were significant declines in eGFR at initiation for patients residing in counties in the highest quintile of COVID-19 mortality rates (9.5 [5.0] mL/min/1.73 m2 pre-COVID-19 vs 9.2 [5.0] mL/min/1.73 m2 during COVID-19; P < .001), but not for patients residing in other counties. The number of patients initiating treatment for incident kidney failure was approximately 30% lower than projected in April 2020. Conclusions and Relevance: In this cross-sectional study of US adults, the COVID-19 pandemic was associated with a substantially lower number of patients initiating treatment for incident kidney failure and treatment initiation at lower levels of kidney function during the first 4 months, particularly for Black patients and people living in counties with high COVID-19 mortality rates.

Medicaid Expansion and Incidence of Kidney Failure among Nonelderly Adults.

BACKGROUND: Low-income individuals without health insurance have limited access to health care. Medicaid expansions may reduce kidney failure incidence by improving access to chronic disease care. METHODS: Using a difference-in-differences analysis, we examined the association between Medicaid expansion status under the Affordable Care Act (ACA) and the kidney failure incidence rate among all nonelderly adults, aged 19-64 years, in the United States, from 2012 through 2018. We compared changes in kidney failure incidence in states that implemented Medicaid expansions with concurrent changes in nonexpansion states during pre-expansion, early postexpansion (years 2 and 3 postexpansion), and later postexpansion (years 4 and 5 postexpansion). RESULTS: The unadjusted kidney failure incidence rate increased in the early years of the study period in both expansion and nonexpansion states before stabilizing. After adjustment for population sociodemographic characteristics, Medicaid expansion status was associated with 2.20 fewer incident cases of kidney failure per million adults per quarter in the early postexpansion period (95% CI, -3.89 to -0.51) compared with nonexpansion status, a 3.07% relative reduction (95% CI, -5.43% to -0.72%). In the later postexpansion period, Medicaid expansion status was not associated with a statistically significant change in kidney failure incidence (-0.56 cases per million per quarter; 95% CI, -2.71 to 1.58) compared with nonexpansion status and the pre-expansion time period. CONCLUSIONS: The ACA Medicaid expansion was associated with an initial reduction in kidney failure incidence among the entire, nonelderly, adult population in the United States; but the changes did not persist in the later postexpansion period. Further study is needed to determine the long-term association between Medicaid expansion and changes in kidney failure incidence.

Association of Medicaid Expansion With 1-Year Mortality Among Patients With End-Stage Renal Disease.

Importance: The Affordable Care Act Medicaid expansion may be associated with reduced mortality, but evidence to date is limited. Patients with end-stage renal disease (ESRD) are a high-risk group that may be particularly affected by Medicaid expansion. Objective: To examine the association of Medicaid expansion with 1-year mortality among nonelderly patients with ESRD initiating dialysis. Design, Setting, and Participants: Difference-in-differences analysis of nonelderly patients initiating dialysis in Medicaid expansion and nonexpansion states from January 2011 to March 2017. Exposure: Living in a Medicaid expansion state. Main Outcomes and Measures: The primary outcome was 1-year mortality. Secondary outcomes were insurance, predialysis nephrology care, and type of vascular access for hemodialysis. Results: A total of 142 724 patients in expansion states (mean age, 50.2 years; 40.2% women) and 93 522 patients in nonexpansion states (mean age, 49.7; 42.4% women) were included. In Medicaid expansion states, 1-year mortality following dialysis initiation declined from 6.9% in the preexpansion period to 6.1% after expansion (change, -0.8 percentage points; 95% CI, -1.1 to -0.5). In nonexpansion states, mortality rates were 7.0% before expansion and 6.8% after expansion (change, -0.2 percentage points; 95% CI, -0.5 to 0.2), yielding an adjusted absolute reduction in mortality in expansion states of -0.6 percentage points (95% CI, -1.0 to -0.2). Mortality reductions were largest for black patients (-1.4 percentage points; 95% CI, -2.2, -0.7; P=.04 for interaction) and patients aged 19 to 44 years (-1.1 percentage points; 95% CI, -2.1 to -0.3; P=.01 for interaction). Expansion was associated with a 10.5-percentage-point (95% CI, 7.7-13.2) increase in Medicaid coverage at dialysis initiation, a -4.2-percentage-point (95% CI, -6.0 to -2.3) decrease in being uninsured, and a 2.3-percentage-point (95% CI, 0.6-4.1) increase in the presence of an arteriovenous fistula or graft. Changes in predialysis nephrology care were not significant. Conclusions and Relevance: Among patients with ESRD initiating dialysis, living in a state that expanded Medicaid under the Affordable Care Act was associated with lower 1-year mortality. If this association is causal, further research is needed to understand what factors may have contributed to this finding.