Rehabilitation After Total Knee Arthroplasty: Do Racial Disparities Exist?

BACKGROUND: Racial disparities in functional outcomes after total knee arthroplasty (TKA) exist. Whether differences in rehabilitation utilization contribute to these disparities remains to be investigated. METHODS: Among 8349 women enrolled in the prospective Women's Health Initiative cohort who underwent primary TKA between 2006 and 2013, rehabilitation utilization was determined through linked Medicare claims data. Postacute discharge destination (home, skilled nursing facility, and inpatient rehabilitation facility), facility length of stay, and number of home health physical therapy (HHPT) and outpatient physical therapy (OPPT) sessions were compared between racial groups. RESULTS: Non-Hispanic black women had worse physical function (median score, 65 vs 70) and higher likelihood of disability (13.2% vs 6.9%) than non-Hispanic white women before surgery. After TKA, black women were more likely to be discharged postacutely to an institutional facility (64.3% vs 54.5%) than white women, were more likely to receive HHPT services (52.6% vs 47.8%), and received more HHPT and OPPT sessions. After stratification by postacute discharge setting, the likelihood of receipt of HHPT or OPPT services was similar between racial groups. No significant difference in receipt of HHPT or OPPT services was found after use of propensity score weighting to balance health and medical characteristics indicating severity of need for physical therapy services. CONCLUSION: Rehabilitation utilization was generally comparable between black and white women who received TKA when accounting for need. There was no evidence of underutilization of post-TKA rehabilitation services, and thus disparities in post-TKA functional outcomes do not appear to be a result of inequitable receipt of rehabilitation care.

The Effects of Reverse Causality and Selective Attrition on the Relationship Between Body Mass Index and Mortality in Postmenopausal Women.

Concerns about reverse causality and selection bias complicate the interpretation of studies of body mass index (BMI, calculated as weight (kg)/height (m)2) and mortality in older adults. The objective of this study was to investigate methodological explanations for the apparent attenuation of obesity-related risks in older adults. We used data from 68,132 participants in the Women's Health Initiative (WHI) clinical trial for this analysis. All of the participants were postmenopausal women aged 50-79 years at baseline (1993-1998). To examine reverse causality and selective attrition, we compared rate ratios from inverse probability of treatment- and censoring-weighted Poisson marginal structural models with results from an unweighted adjusted Poisson regression model. The estimated mortality rate ratios and 95% confidence intervals for BMIs of 30.0-34.9, 35.0-39.9 and ≥40.0 were 0.86 (95% confidence interval (CI): 0.77, 0.96), 0.85 (95% CI: 0.72, 0.99), and 0.88 (95% CI: 0.72, 1.07), respectively, in the unweighted model. The corresponding mortality rate ratios were 0.96 (95% CI: 0.86, 1.07), 1.12 (95% CI: 0.97, 1.29), and 1.31 95% CI: (1.08, 1.57), respectively, in the marginal structural model. Results from the inverse probability of treatment- and censoring-weighted marginal structural model were attenuated in low BMI categories and increased in high BMI categories. The results demonstrate the importance of accounting for reverse causality and selective attrition in studies of older adults.

How Do Gender Differences in Quality of Care Vary Across Medicare Advantage Plans?

BACKGROUND: Healthcare Effectiveness Data and Information Set (HEDIS) quality measures have long been used to compare care across health plans and to study racial/ethnic and socioeconomic disparities among Medicare Advantage (MA) beneficiaries. However, possible gender differences in seniors' quality of care have received less attention. OBJECTIVE: To test for the presence and nature of any gender differences in quality of care across MA Plans, overall and by domain; to identify those most at risk of poor care. DESIGN: Cross-sectional analysis of individual-level HEDIS measure scores from 23.8 million records using binomial mixed-effect models to estimate the effect of gender on performance. For each measure, we assess variation in gender gaps and their correlation with plan performance. PARTICIPANTS: Beneficiaries from 456 MA plans in 2011-2012 HEDIS data. MAIN MEASURES: Performance on 32 of 34 HEDIS measures which were available in both measurement years. The two excluded measures had mean performance scores below 10%. KEY RESULTS: Women experienced better quality of care than men for 22/32 measures, with most pertaining to screening or treatment. Men experienced better quality on nine measures, including four related to cardiovascular disease and three to potentially harmful drug-disease interactions. Plans varied substantially in the magnitude of gender gaps for 21/32 measures; in general, the gender gap in quality of care was least favorable to men in low-performing plans. CONCLUSIONS: Women generally experienced better quality of care than men. However, women experienced poorer care for cardiovascular disease-related intermediate outcomes and potentially harmful drug-disease interactions. Quality improvement may be especially important for men in low-performing plans and for cardiovascular-related care and drug-disease interactions for women. Gender-stratified reporting could reveal gender gaps, identify plans for which care varies by gender, and motivate efforts to address faults and close the gaps in the delivery system.

Impact of incident diabetes on atherosclerotic cardiovascular disease according to statin use history among postmenopausal women.

To compare impact of incident diabetes on atherosclerotic cardiovascular disease (ASCVD) risk among postmenopausal women according to statin use. Prospective data from 120,499 postmenopausal women without prevalent diabetes or cardiovascular disease at baseline from the Women's Health Initiative were used. Incident diabetes was self-reported annually and defined as treatment with pills or injectable medication for diabetes. Current statin use was determined at enrollment and years 1, 3, 6, 9 and 13.5 in the three clinical trial arms, and at baseline, year 3, and 13.5 for the observational study. The primary outcome was incident ASCVD events, self-reported annually and adjudicated by blinded local and central physicians. Incident diabetes and statin use status were fitted as time-varying covariates in Cox regression models to assess ASCVD risk during an average follow-up of 13.6 years. For those not on statins at the time of diabetes diagnosis, there was a 42 % increased risk of ASCVD [hazard ratio (HR) 1.42, 95 % CI 1.28-1.58] among women with incident diabetes versus those without diabetes. Among women on statins, there was a 39 % increased risk of ASCVD (HR 1.39, 95 % CI 1.12-1.74) in women with incident diabetes versus those without diabetes. The increased ASCVD risk due to diabetes was similar between women before or after initiating statins (P = 0.89). Whether diabetes was diagnosed before or after statin use did not alter the increased risk of ASCVD associated with diabetes. Mitigating the increased incidence of diabetes in statin users could increase the ASCVD benefit-to-risk ratio of statins.

All-cause, cardiovascular, and cancer mortality rates in postmenopausal white, black, Hispanic, and Asian women with and without diabetes in the United States: the Women's Health Initiative, 1993-2009.

Using data from the Women's Health Initiative (1993-2009; n = 158,833 participants, of whom 84.1% were white, 9.2% were black, 4.1% were Hispanic, and 2.6% were Asian), we compared all-cause, cardiovascular, and cancer mortality rates in white, black, Hispanic, and Asian postmenopausal women with and without diabetes. Cox proportional hazard models were used for the comparison from which hazard ratios and 95% confidence intervals were computed. Within each racial/ethnic subgroup, women with diabetes had an approximately 2-3 times higher risk of all-cause, cardiovascular, and cancer mortality than did those without diabetes. However, the hazard ratios for mortality outcomes were not significantly different between racial/ethnic subgroups. Population attributable risk percentages (PARPs) take into account both the prevalence of diabetes and hazard ratios. For all-cause mortality, whites had the lowest PARP (11.1, 95% confidence interval (CI): 10.1, 12.1), followed by Asians (12.9, 95% CI: 4.7, 20.9), blacks (19.4, 95% CI: 15.0, 23.7), and Hispanics (23.2, 95% CI: 14.8, 31.2). To our knowledge, the present study is the first to show that hazard ratios for mortality outcomes were not significantly different between racial/ethnic subgroups when stratified by diabetes status. Because of the "amplifying" effect of diabetes prevalence, efforts to reduce racial/ethnic disparities in the rate of death from diabetes should focus on prevention of diabetes.

The "Birth-Centered Outcomes Research Engagement (B-CORE) in Medi-Cal" Project: Community-Generated Recommendations to Decrease Maternal Mortality and Severe Maternal Morbidity.

BACKGROUND: Through applied research and health care quality improvement, California has achieved a maternal mortality (MM) rate significantly lower than that measured nationally. However, Medicaid (Medi-Cal)-insured births in the state continue to experience disproportionate shares of MM and severe maternal morbidity (SMM), which often precedes death. Failure to engage the Medi-Cal community in this work may impede efforts to increase equity. METHODS: This community engagement project used deliberative democracy methods to engage stakeholders with lived experience in California's Medi-Cal perinatal care system to generate an actionable and specific agenda of recommendations to decrease MM and SMM in the Medi-Cal population. FINDINGS: A total of 37 Medi-Cal stakeholders-representing birthing people, providers, health plan administrators, and advocates-participated in longitudinal co-learning sessions on the topics of MM/SMM in Medi-Cal. Most of these stakeholders (75.7%) then participated in deliberation sessions. Deliberation recommendations fell into five distinct categories: Medi-Cal perinatal covered benefits, data collection and dissemination, patient experience and its link to care quality, Medi-Cal reimbursement rates, and accountability with respect to racism in perinatal care. Stakeholders identified the Medi-Cal system actors best positioned to implement specific recommendations to directly impact MM/SMM. CONCLUSIONS: This project demonstrates the feasibility and success of using deliberative democracy methods to generate local and community-generated solutions to critical problems in health equity. Active and engaged stakeholders were keen to identify both immediate actions and long-term research and quality improvement paradigm shifts to support birth equity in Medi-Cal.

Birth-Centered Outcomes Research Engagement (B-CORE) in Medi-Cal: Community-Generated Recommendations to Decrease Maternal Mortality and Severe Maternal Morbidity.

California leads the nation with its relatively low rate of maternal deaths during pregnancy and the postpartum period. However, individuals insured via Medi-Cal suffer a disproportionate share of maternal deaths and severe complications at birth; within this group of publicly insured individuals, certain racial and/or ethnic groups have even higher rates of poor outcomes. The state can attribute part of its success in lowering rates of maternal mortality (MM) to the implementation of a data-driven statewide portfolio of quality improvement activities focused on the leading causes of maternal death. This quality improvement infrastructure has not previously been leveraged to respond in a focused way to the relatively large shares of MM and morbidity still seen in the Medi-Cal-insured population. B-CORE aimed to expand on existing statewide quality improvement efforts to effectively mitigate these adverse outcomes in Medi-Cal births by engaging Medi-Cal stakeholders.

Neighborhood Socioeconomic Status, Green Space, and Walkability and Risk for Falls Among Postmenopausal Women: The Women's Health Initiative.

PURPOSE: This study estimated associations between neighborhood socioeconomic status (NSES), walkability, green space, and incident falls among postmenopausal women and evaluated modifiers of these associations, including study arm, race and ethnicity, baseline household income, baseline walking, age at enrollment, baseline low physical functioning, baseline fall history, climate region, and urban-rural residence. METHODS: The Women's Health Initiative recruited a national sample of postmenopausal women (50-79 years) across 40 U.S. clinical centers and conducted yearly assessments from 1993 to 2005 (n = 161,808). Women reporting a history of hip fracture or walking limitations were excluded, yielding a final sample of 157,583 participants. Falling was reported annually. NSES (income/wealth, education, occupation), walkability (population density, diversity of land cover, nearby high-traffic roadways), and green space (exposure to vegetation) were calculated annually and categorized into tertiles (low, intermediate, high). Generalized estimating equations assessed longitudinal relationships. RESULTS: NSES was associated with falling before adjustment (high vs. low, odds ratio, 1.01; 95% confidence interval, 1.00-1.01). Walkability was significantly associated with falls after adjustment (high vs. low, odds ratio, 0.99; 95% confidence interval, 0.98-0.99). Green space was not associated with falling before or after adjustment. Study arm, race and ethnicity, household income, age, low physical functioning, fall history, and climate region modified the relationship between NSES and falling. Race and ethnicity, age, fall history, and climate region modified relationships between walkability and green space and falling. CONCLUSIONS: Our results did not show strong associations of NSES, walkability, or green space with falling. Future research should incorporate granular environmental measures that may directly relate to physical activity and outdoor engagement.

To Address Women's Health Inequity, It Must First Be Measured.

Research and data collection related to what is historically known as "women's health" is consistently underfunded and marginalizes the health risks and experiences of women of color and transgender people. In the wake of the pandemic, the United States has an opportunity to redesign and reimagine a modern public health data infrastructure that centers equity and elevates the health and well-being of under-represented communities, including the full spectrum of gender identities. This piece offers a blueprint for transformational change in how the United States collects, interprets, and shares critical data to deliver greater health justice for all.

Association of neighborhood Walk Score with accelerometer-measured physical activity varies by neighborhood socioeconomic status in older women.

The built environment can influence physical activity behavior. Walk Score is a widely used measure of the neighborhood built environment to support walking. However, studies of the association between Walk Score and accelerometer-measured physical activity are equivocal and no studies have examined this relationship among older adults. We analyzed data from a large, diverse sample of women (n = 5650) with a mean age of 79.5 (SD = 6.7) at time of accelerometry wear in the Women's Health Initiative Objective Physical Activity Cardiovascular Health Study in the United States to examine associations between neighborhood Street Smart Walk Score (SSWS) and accelerometer-measured physical activity. Participants wore triaxial accelerometers for seven days and SSWS was determined from home addresses. 67 % of the sample lived in "car-dependent" locations (SSWS 0-49 out of 100); only 3 % lived in "walker's paradise" locations (SSWS 90-100). The multivariable model indicated an association between SSWS and accelerometer-measured physical activity (steps/day) in the total sample. The association varied by neighborhood socioeconomic status; in high socioeconomic status neighborhoods, higher SWSS was associated with greater steps per day, while no significant association between SWSS and physical activity was observed in low socioeconomic neighborhoods. This study should catalyze furtherresearch regarding the utility of SSWS in determining neighborhood walkability for older women across different neighborhood settings and suggests other built environment factors must be considered when determining walkability. Future studies should examine what factors influence walkability and develop age-relevant methods to assess and characterize neighborhood walkability.

Neighborhood socioeconomic status and cognitive function in women.

OBJECTIVES: We examined whether neighborhood socioeconomic status (NSES) is associated with cognitive functioning in older US women and whether this relationship is explained by associations between NSES and vascular, health behavior, and psychosocial factors. METHODS: We assessed women aged 65 to 81 years (n = 7479) who were free of dementia and took part in the Women's Health Initiative Memory Study. Linear mixed models examined the cross-sectional association between an NSES index and cognitive functioning scores. A base model adjusted for age, race/ethnicity, education, income, marital status, and hysterectomy. Three groups of potential confounders were examined in separate models: vascular, health behavior, and psychosocial factors. RESULTS: Living in a neighborhood with a 1-unit higher NSES value was associated with a level of cognitive functioning that was 0.022 standard deviations higher (P = .02). The association was attenuated but still marginally significant (P < .1) after adjustment for confounders and, according to interaction tests, stronger among younger and non-White women. CONCLUSIONS: The socioeconomic status of a woman's neighborhood may influence her cognitive functioning. This relationship is only partially explained by vascular, health behavior, or psychosocial factors. Future research is needed on the longitudinal relationships between NSES, cognitive impairment, and cognitive decline.

On the joint role of non-Hispanic Black race/ethnicity and weight status in predicting postmenopausal weight gain.

OBJECTIVES: To determine how baseline weight status contributes to differences in postmenopausal weight gain among non-Hispanic Blacks (NHBs) and non-Hispanic Whites (NHWs). METHODS: Data were included from 70,750 NHW and NHB postmenopausal women from the Women's Health Initiative Observational Study (WHI OS). Body Mass Index (BMI) at baseline was used to classify women as having normal weight, overweight, obese class I, obese class II or obese class III. Cox proportional hazards was used to estimate the hazard of a 10% or more increase in weight from baseline. RESULTS: In both crude and adjusted models, NHBs were more likely to experience ≥10% weight gain than NHWs within the same category of baseline weight status. Moreover, NHBs who were normal weight at baseline were most likely to experience ≥10% weight gain in both crude and adjusted models. Age-stratified results were consistent with overall findings. In all age categories, NHBs who were normal weight at baseline were most likely to experience ≥10% weight gain. Based on the results of adjusted models, the joint influence of NHB race/ethnicity and weight status on risk of postmenopausal weight gain was both sub-additive and sub-multiplicative. CONCLUSION: NHBs are more likely to experience postmenopausal weight gain than NHWs, and the disparity in risk is most pronounced among those who are normal weight at baseline. To address the disparity in postmenopausal obesity, future studies should focus on identifying and modifying factors that promote weight gain among normal weight NHBs.

Bridging the Chasm between Pregnancy and Health over the Life Course: A National Agenda for Research and Action.

BACKGROUND: Many pregnant people find no bridge to ongoing specialty or primary care after giving birth, even when clinical and social complications of pregnancy signal need. Black, indigenous, and all other women of color are especially harmed by fragmented care and access disparities, coupled with impacts of racism over the life course and in health care. METHODS: We launched the initiative "Bridging the Chasm between Pregnancy and Health across the Life Course" in 2018, bringing together patients, advocates, providers, researchers, policymakers, and systems innovators to create a National Agenda for Research and Action. We held a 2-day conference that blended storytelling, evidence analysis, and consensus building to identify key themes related to gaps in care and root causes of inequities. In 2019, more than 70 stakeholders joined six working groups to reach consensus on strategic priorities based on equity, innovation, effectiveness, and feasibility. FINDINGS: Working groups identified six key strategic areas for bridging the chasm. These include: 1) progress toward eliminating institutional and interpersonal racism and bias as a requirement for accreditation of health care institutions, 2) infrastructure support for community-based organizations, 3) extension of holistic team-based care to the postpartum year and beyond, with integration of doulas and community health workers on the team, 4) extension of Medicaid coverage and new quality and pay-for-performance metrics to link maternity care and primary care, 5) systems to preserve maternal narratives and data across providers, and 6) alignment of research with women's lived experiences. CONCLUSIONS: The resulting agenda presents a path forward to remedy the structural chasms in women's health care, with key roles for advocates, policymakers, researchers, health care leaders, educators, and the media.

Racial/Ethnic Disparities in Physical Function Before and After Total Knee Arthroplasty Among Women in the United States.

Importance: Although racial/ethnic differences in functional outcomes after total knee arthroplasty (TKA) exist, whether such differences are associated with differences in presurgical physical function (PF) has not been thoroughly investigated. Objective: To examine trajectories of PF by race/ethnicity before and after TKA among older women. Design, Setting, and Participants: This cohort study was conducted among the prospective Women's Health Initiative with linked Medicare claims data. A total of 10 325 community-dwelling women throughout the United States with Medicare fee-for-service underwent primary TKA between October 1, 1993, and December 31, 2014, and were followed up through March 31, 2017. Exposures: Race/ethnicity comparisons between Hispanic or Latina women, non-Hispanic black or African American women, and non-Hispanic white women (hereafter referred to as Hispanic, black, and white women, respectively). Main Outcomes and Measures: Physical functioning scale scores and self-reported activity limitations with walking 1 block, walking several blocks, and climbing 1 flight of stairs were measured by the RAND 36-Item Health Survey during the decade before and after TKA, with a median of 9 PF measurements collected per participant over time. Results: In total, 9528 white women (mean [SD] age at surgery, 74.6 [5.5] years), 622 black women (mean [SD] age at surgery, 73.1 [5.3] years), and 175 Hispanic women (mean [SD] age at surgery, 73.1 [5.2] years) underwent TKA. During the decade prior to TKA, black women had lower PF scores than white women (mean difference, -5.8 [95% CI, -8.0 to -3.6]) and higher odds of experiencing difficulty walking a single block (5 years before TKA: odds ratio, 1.86 [95% CI, 1.57-2.21]), walking multiple blocks (odds ratio, 2.14 [95% CI, 1.83-2.50]), and climbing 1 flight of stairs (odds ratio, 1.81 [95% CI, 1.55-2.12]). After TKA, black women continued to have lower PF scores throughout the decade (mean difference 1 year after TKA, -7.8 [95% CI, -10.8 to -4.9]). After adjusting for preoperative PF scores, PF scores after TKA were attenuated (mean difference 1 year after TKA, -3.0 [95% CI, -5.3 to -0.7]), with no statistically significant differences in long-term follow-up. Hispanic women had similar PF scores to white women during the pre-TKA and post-TKA periods. Conclusions and Relevance: This study suggests that black women had significantly poorer PF than white women during the decades before and after TKA. Poorer PF after surgery was associated with poorer preoperative PF. Reducing disparities in post-TKA functional outcomes should target maintenance of function preoperatively in the early stages of arthritic disease and/or reduction of delays to receiving TKA once need arises.

It's Absolutely Relative: The Effect of Age on the BMI-Mortality Relationship in Postmenopausal Women.

OBJECTIVE: The use of relative and absolute effect estimates has important implications for the interpretation of study findings. Likewise, examining additive and multiplicative interaction can lead to differing conclusions about the joint effects of two exposure variables. The aim of this paper is to examine the relationship between BMI and mortality on the relative and absolute scales and investigate interaction between BMI and age. METHODS: Data from 68,132 participants in the Women's Health Initiative (WHI) study were used. The risk ratio and risk difference of BMI on mortality were estimated. A product term was also included to examine interaction between BMI and age on the multiplicative scale, and the relative excess risk of interaction was calculated to measure additive interaction. RESULTS: Results demonstrated that the mortality risk ratio decreased as women aged, but the mortality risk difference increased as women aged. Evidence of additive and multiplicative interaction between age and BMI was found. CONCLUSIONS: In postmenopausal women, the relative mortality risk associated with high BMI decreased with increasing age, but the absolute risk of high BMI increased with increasing age. This indicates the importance of considering the interaction between age and BMI to understand mortality risk in older women.

Developing predictive models of health literacy.

INTRODUCTION: Low health literacy (LHL) remains a formidable barrier to improving health care quality and outcomes. Given the lack of precision of single demographic characteristics to predict health literacy, and the administrative burden and inability of existing health literacy measures to estimate health literacy at a population level, LHL is largely unaddressed in public health and clinical practice. To help overcome these limitations, we developed two models to estimate health literacy. METHODS: We analyzed data from the 2003 National Assessment of Adult Literacy (NAAL), using linear regression to predict mean health literacy scores and probit regression to predict the probability of an individual having 'above basic' proficiency. Predictors included gender, age, race/ethnicity, educational attainment, poverty status, marital status, language spoken in the home, metropolitan statistical area (MSA) and length of time in U.S. RESULTS: All variables except MSA were statistically significant, with lower educational attainment being the strongest predictor. Our linear regression model and the probit model accounted for about 30% and 21% of the variance in health literacy scores, respectively, nearly twice as much as the variance accounted for by either education or poverty alone. CONCLUSIONS: Multivariable models permit a more accurate estimation of health literacy than single predictors. Further, such models can be applied to readily available administrative or census data to produce estimates of average health literacy and identify communities that would benefit most from appropriate, targeted interventions in the clinical setting to address poor quality care and outcomes related to LHL.

Is Interpersonal Abuse Associated with Sexual (Dis)satisfaction among Postmenopausal Women?

PURPOSE: To investigate associations between past-year verbal and/or physical abuse (VA/PA) and sexual (dis)satisfaction, that is, global or frequency-related (dis)satisfactions with sexual activity, among postmenopausal women in the Women's Health Initiative. PROCEDURES: A cross-sectional analysis of archival data was performed from the subset of 83,329 Women's Health Initiative participants (clinical trial and/or observational study components) who reported sexual activity in the year before baseline. Associations between VA/PA and global frequency (dis)satisfactions were modeled using logistic regression. MAIN FINDINGS: Most participants reported sexual satisfaction (global, 77%; frequency related, 66%). Disappointment with sexual frequency, specifically a desire for more frequent sex, was the most common dissatisfaction expressed. Past-year VA/PA exposure was reported by 9,410 participants (11%). In regression models adjusted for sociodemographic, health and health risk, and menopausal symptom variables, VA/PA was associated with higher rates of global (35% VA/PA exposed vs. 22% non-exposed; adjusted odds ratio, 1.66; 95% confidence interval, 1.53-1.80) and frequency-related dissatisfactions (50% of VA/PA exposed vs. 32% of non-exposed; adjusted odds ratio, 1.73; 95% confidence interval, 1.57-1.90). CONCLUSIONS: Sexual satisfaction was common, but not universally reported by study participants. Sexual dissatisfactions were overrepresented in VA/PA-exposed participants and associated with a desire for more frequent sexual activity. Opportunities for postmenopausal women to receive clinician-led education about safe and healthy ways to increase sexual activity are needed. Further research on this topic, particularly efforts to characterize safety concerns as well as modifiable barriers to satisfying sexual activity among postmenopausal women with recent VA/PA, would ensure that these interventions are evidence based.

Ambient air pollution and lung cancer risk among never-smokers in the Women's Health Initiative.

BACKGROUND: Ambient air pollution is classified as a human carcinogen by the International Agency for Research on Cancer (IARC). However, epidemiologic studies supporting this classification have focused on lung cancer mortality rather than incidence, and spatial and temporal resolutions of exposure estimates have varied considerably across studies. METHODS: We evaluated the association of outdoor air pollution and lung cancer incidence among never-smoking participants of the Women's Health Initiative (WHI) study, a large, US-based cohort of postmenopausal women (N = 65,419; 265 cases). We used geospatial models to estimate exposures to fine particulate matter (PM2.5) and nitrogen dioxide (NO2) based on residential addresses at baseline and throughout follow-up. We also characterized exposures to traffic-related air pollution by proximity to major roadways. We estimated hazard ratios (HRs) for the risk of lung cancer in association with these exposure metrics using Cox proportional hazards regression models. RESULTS: No compelling associations of PM2.5 and NO2 exposures with lung cancer risk were observed. An increased risk of lung cancer was observed when comparing those individuals with residences <50 versus ≥200 meters from a primary limited access highway (HR = 5.23; 95% confidence interval = 1.94, 14.13). CONCLUSIONS: Our results do not exclude lung cancer risk estimates observed in association with PM2.5 and NO2 exposures identified in previous studies. Our results suggest that residential proximity to major roadways may be a proxy for carcinogenic exposures not correlated with PM2.5 or NO2 levels. New studies of air pollution and lung cancer incidence should characterize additional aspects of proximity to major roadways.

Challenges for multilevel health disparities research in a transdisciplinary environment.

Numerous factors play a part in health disparities. Although health disparities are manifested at the level of the individual, other contexts should be considered when investigating the associations of disparities with clinical outcomes. These contexts include families, neighborhoods, social organizations, and healthcare facilities. This paper reports on health disparities research as a multilevel research domain from the perspective of a large national initiative. The Centers for Population Health and Health Disparities (CPHHD) program was established by the NIH to examine the highly dimensional, complex nature of disparities and their effects on health. Because of its inherently transdisciplinary nature, the CPHHD program provides a unique environment in which to perform multilevel health disparities research. During the course of the program, the CPHHD centers have experienced challenges specific to this type of research. The challenges were categorized along three axes: sources of subjects and data, data characteristics, and multilevel analysis and interpretation. The CPHHDs collectively offer a unique example of how these challenges are met; just as importantly, they reveal a broad range of issues that health disparities researchers should consider as they pursue transdisciplinary investigations in this domain, particularly in the context of a large team science initiative.