Overdose, Behavioral Health Services, and Medications for Opioid Use Disorder After a Nonfatal Overdose.

Importance: Recognizing and providing services to individuals at highest risk for drug overdose are paramount to addressing the drug overdose crisis. Objective: To examine receipt of medications for opioid use disorder (MOUD), naloxone, and behavioral health services in the 12 months after an index nonfatal drug overdose and the association between receipt of these interventions and fatal drug overdose. Design, Setting, and Participants: This cohort study was conducted in the US from January 2020 to December 2021 using claims, demographic, mortality, and other data from the Centers for Medicare & Medicaid Services, the Centers for Disease Control and Prevention, and other sources. The cohort comprised Medicare fee-for-service beneficiaries aged 18 years or older with International Statistical Classification of Diseases, Tenth Revision, Clinical Modification codes for a nonfatal drug overdose. Data analysis was performed from February to November 2023. Exposures: Demographic and clinical characteristics, substance use disorder, and psychiatric comorbidities. Main Outcomes and Measures: Receipt of MOUD, naloxone, and behavioral health services as well as subsequent nonfatal and fatal drug overdoses. Results: The cohort consisted of 136 762 Medicare beneficiaries (80 140 females [58.6%]; mean (SD) age of 68.2 [15.0] years) who experienced an index nonfatal drug overdose in 2020. The majority of individuals had Hispanic (5.8%), non-Hispanic Black (10.9%), and non-Hispanic White (78.8%) race and ethnicity and lived in metropolitan areas (78.9%). In the 12 months after their index nonfatal drug overdose, 23 815 beneficiaries (17.4%) experienced at least 1 subsequent nonfatal drug overdose and 1323 (1.0%) died of a fatal drug overdose. Opioids were involved in 72.2% of fatal drug overdoses. Among the cohort, 5556 (4.1%) received any MOUD and 8530 (6.2%) filled a naloxone prescription in the 12 months after the index nonfatal drug overdose. Filling a naloxone prescription (adjusted odds ratio [AOR], 0.70; 95% CI, 0.56-0.89), each percentage of days receiving methadone (AOR, 0.98; 95% CI, 0.98-0.99) or buprenorphine (AOR, 0.99; 95% CI, 0.98-0.99), and receiving behavioral health assessment or crisis services (AOR, 0.25; 95% CI, 0.22-0.28) were all associated with reduced adjusted odds of fatal drug overdose in the 12 months after the index nonfatal drug overdose. Conclusions and Relevance: This cohort study found that, despite their known association with reduced risk of a fatal drug overdose, only a small percentage of Medicare beneficiaries received MOUD or filled a naloxone prescription in the 12 months after a nonfatal drug overdose. Efforts to improve access to behavioral health services; MOUD; and overdose-prevention strategies, such as prescribing naloxone and linking individuals to community-based health care settings for ongoing care, are needed.

Social Vulnerability and the Prevalence of Opioid Use Disorder Among Older Medicare Beneficiaries in U.S. Counties.

OBJECTIVES: Recent research has investigated the factors associated with the prevalence of opioid use disorder (OUD) among older adults (65+), which has rapidly increased in the past decade. However, little is known about the relationship between social vulnerability and the prevalence of OUD, and even less is about whether the correlates of the prevalence of OUD vary across the social vulnerability spectrum. This study aims to fill these gaps. METHODS: We assemble a county-level data set in the contiguous United States (U.S.) by merging 2021 Medicare claims with the CDC's social vulnerability index and other covariates. Using the total number of older beneficiaries with OUD as the dependent variable and the total number of older beneficiaries as the offset, we implement a series of nested negative binomial regression models and then analyze by social vulnerability quartiles. RESULTS: Higher social vulnerability is associated with higher prevalence of OUD in U.S. counties. This association cannot be fully explained by the differences in the characteristics of older Medicare beneficiaries (e.g., average age) and/or other social conditions (e.g., social capital) across counties. Moreover, the group comparison tests indicate correlates of the prevalence of OUD vary across social vulnerability quartiles in that the average number of mental disorders is positively related to OUD prevalence in the least and the most vulnerable counties and social capital benefits the less vulnerable counties. DISCUSSION: A perspective drawing upon contextual factors, especially social vulnerability, may be more effective in reducing OUD among older adults in U.S. counties than a one-size-fits-all approach.

Oral Health Among Medicare Beneficiaries in Nursing Homes.

This cross-sectional study investigates rates of dental problems among Medicare beneficiaries in nursing homes and characteristics associated with these rates.

Association of Receipt of Opioid Use Disorder-Related Telehealth Services and Medications for Opioid Use Disorder With Fatal Drug Overdoses Among Medicare Beneficiaries Before and During the COVID-19 Pandemic.

Importance: Federal emergency authorities were invoked during the COVID-19 pandemic to expand clinical telehealth for opioid use disorder (OUD). Objective: To examine the association of the receipt of telehealth services and medications for OUD (MOUD) with fatal drug overdoses before and during the pandemic. Design, Setting, and Participants: This cohort study used exploratory longitudinal data from 2 cohorts (prepandemic cohort: September 1, 2018, to February 29, 2020; pandemic cohort: September 1, 2019, to February 28, 2021) of Medicare Fee-for-Service beneficiaries aged 18 years or older initiating an episode of OUD-related care using Medicare Fee-for-Service data from the Centers for Medicare & Medicaid Services and National Death Index data from the Centers for Disease Control and Prevention. Data analysis was performed from September 19 to October 17, 2022. Exposures: Prepandemic vs pandemic cohort demographic, medical, substance use, and psychiatric characteristics. Main Outcomes and Measures: Receipt of OUD-related telehealth services, receipt of MOUD, and fatal drug overdose. Results: The prepandemic cohort comprised 105 162 beneficiaries (58.1% female; 67.6% aged 45-74 years). The pandemic cohort comprised 70 479 beneficiaries (57.1% female; 66.3% aged 45-74 years). The rate of all-cause mortality was higher in the pandemic cohort (99.9 per 1000 beneficiaries; 7041 deaths) than in the prepandemic cohort (76.8 per 1000; 8076 deaths) (P < .001). The rate of fatal drug overdoses was higher in the pandemic cohort (5.1 per 1000 beneficiaries; n = 358) than in the prepandemic cohort (3.7 per 1000; n = 391) (P < .001). The percentage of deaths due to a fatal drug overdose was similar in the prepandemic (4.8%) and pandemic (5.1%) cohorts (P = .49). In multivariable analysis of the pandemic cohort, receipt of OUD-related telehealth was associated with a significantly lower adjusted odds ratio (aOR) for fatal drug overdose (aOR, 0.67; 95% CI, 0.48-0.92) as was receipt of MOUD from opioid treatment programs (aOR, 0.41; 95% CI, 0.25-0.68) and receipt of buprenorphine in office-based settings (aOR, 0.62; 95% CI, 0.43-0.91) compared with those not receiving MOUD; receipt of extended-release naltrexone in office-based settings was not associated with lower odds for fatal drug overdose (aOR, 1.16; 95% CI, 0.41-3.26). Conclusions and Relevance: This cohort study found that, among Medicare beneficiaries initiating OUD-related care during the COVID-19 pandemic, receipt of OUD-related telehealth services was associated with reduced risk for fatal drug overdose, as was receipt of MOUD from opioid treatment programs and receipt of buprenorphine in office-based settings. Strategies to expand provision of MOUD, increase retention in care, and address co-occurring physical and behavioral health conditions are needed.

Neighborhood characteristics and opioid use disorder among older Medicare beneficiaries: An examination of the role of the COVID-19 pandemic.

This study investigates how the associations between residential characteristics and the risk of opioid user disorder (OUD) among older Medicare beneficiaries (age≥65) are altered by the COVID-19 pandemic. Applying matching techniques and multilevel modeling to the Medicare fee-for-service claims data, this study finds that county-level social isolation, concentrated disadvantage, and residential stability are significantly associated with OUD among older adults (N = 1,080,350) and that those living in counties with low levels of social isolation and residential stability experienced a heightened risk of OUD during the pandemic. The results suggest that the COVID-19 pandemic has aggravated the impacts of residential features on OUD.

Multiscale dimensions of county-level disparities in opioid use disorder rates among older Medicare beneficiaries.

Background: Opioid use disorder (OUD) among older adults (age ≥ 65) is a growing yet underexplored public health concern and previous research has mainly assumed that the spatial process underlying geographic patterns of population health outcomes is constant across space. This study is among the first to apply a local modeling perspective to examine the geographic disparity in county-level OUD rates among older Medicare beneficiaries and the spatial non-stationarity in the relationships between determinants and OUD rates. Methods: Data are from a variety of national sources including the Centers for Medicare & Medicaid Services beneficiary-level data from 2020 aggregated to the county-level and county-equivalents, and the 2016-2020 American Community Survey (ACS) 5-year estimates for 3,108 contiguous US counties. We use multiscale geographically weighted regression to investigate three dimensions of spatial process, namely "level of influence" (the percentage of older Medicare beneficiaries affected by a certain determinant), "scalability" (the spatial process of a determinant as global, regional, or local), and "specificity" (the determinant that has the strongest association with the OUD rate). Results: The results indicate great spatial heterogeneity in the distribution of OUD rates. Beneficiaries' characteristics, including the average age, racial/ethnic composition, and the average hierarchical condition categories (HCC) score, play important roles in shaping OUD rates as they are identified as primary influencers (impacting more than 50% of the population) and the most dominant determinants in US counties. Moreover, the percentage of non-Hispanic white beneficiaries, average number of mental health conditions, and the average HCC score demonstrate spatial non-stationarity in their associations with the OUD rates, suggesting that these variables are more important in some counties than others. Conclusions: Our findings highlight the importance of a local perspective in addressing the geographic disparity in OUD rates among older adults. Interventions that aim to reduce OUD rates in US counties may adopt a place-based approach, which could consider the local needs and differential scales of spatial process.

Receipt of Telehealth Services, Receipt and Retention of Medications for Opioid Use Disorder, and Medically Treated Overdose Among Medicare Beneficiaries Before and During the COVID-19 Pandemic.

Importance: Federal emergency authorities were invoked during the COVID-19 pandemic to expand use of telehealth for new and continued care, including provision of medications for opioid use disorder (MOUD). Objective: To examine receipt of telehealth services, MOUD (methadone, buprenorphine, and extended-release [ER] naltrexone) receipt and retention, and medically treated overdose before and during the COVID-19 pandemic. Design, Setting, and Participants: This exploratory longitudinal cohort study used data from the US Centers for Medicare & Medicaid Services from September 2018 to February 2021. Two cohorts (before COVID-19 pandemic from September 2018 to February 2020 and during COVID-19 pandemic from September 2019 to February 2021) of Medicare fee-for-service beneficiaries 18 years and older with an International Statistical Classification of Diseases, Tenth Revision, Clinical Modification OUD diagnosis. Exposures: Pre-COVID-19 pandemic vs COVID-19 pandemic cohort demographic characteristics, medical and substance use, and psychiatric comorbidities. Main Outcomes and Measures: Receipt and retention of MOUD, receipt of OUD and behavioral health-related telehealth services, and experiencing medically treated overdose. Results: The pre-COVID-19 pandemic cohort comprised 105 240 beneficiaries; of these, 61 152 (58.1%) were female, 71 152 (67.6%) were aged 45 to 74 years, and 82 822 (79.5%) non-Hispanic White. The COVID-19 pandemic cohort comprised 70 538 beneficiaries; of these, 40 257 (57.1%) were female, 46 793 (66.3%) were aged 45 to 74 years, and 55 510 (79.7%) were non-Hispanic White. During the study period, a larger percentage of beneficiaries in the pandemic cohort compared with the prepandemic cohort received OUD-related telehealth services (13 829 [19.6%] vs 593 [0.6%]; P < .001), behavioral health-related telehealth services (28 902 [41.0%] vs 1967 [1.9%]; P < .001), and MOUD (8854 [12.6%] vs 11 360 [10.8%]; P < .001). The percentage experiencing a medically treated overdose during the study period was similar (18.5% [19 491 of 105 240] in the prepandemic cohort vs 18.4% [13 004 of 70 538] in the pandemic cohort; P = .65). Receipt of OUD-related telehealth services in the pandemic cohort was associated with increased odds of MOUD retention (adjusted odds ratio [aOR], 1.27; 95% CI, 1.14-1.41) and lower odds of medically treated overdose (aOR, 0.67; 95% CI, 0.63-0.71). Among beneficiaries in the pandemic cohort, those receiving MOUD from opioid treatment programs only (aOR, 0.54; 95% CI, 0.47-0.63) and those receiving buprenorphine from pharmacies only (aOR, 0.91; 95% CI, 0.84-0.98) had lower odds of medically treated overdose compared with beneficiaries who did not receive MOUD. Conclusions and Relevance: Emergency authorities to expand use of telehealth and provide flexibilities for MOUD provision during the pandemic were used by Medicare beneficiaries initiating an episode of OUD-related care and were associated with improved retention in care and reduced odds of medically treated overdose. Strategies to expand provision of MOUD and increase retention in care are urgently needed.

County social isolation and opioid use disorder among older adults: A longitudinal analysis of Medicare data, 2013-2018.

This study aims to fill three knowledge gaps: (1) unclear role of ecological factors in shaping older adults' risk of opioid use disorder (OUD), (2) a lack of longitudinal perspective in OUD research among older adults, and (3) underexplored racial/ethnic differences in the determinants of OUD in older populations. This study estimates the effects of county-level social isolation, concentrated disadvantage, and income inequality on older adults' risk of OUD using longitudinal data analysis. We merged the 2013-2018 Medicare population (aged 65+) data to the American Community Survey 5-year county-level estimates to create a person-year dataset (N = 47,291,217 person-years) and used conditional logit fixed-effects modeling to test whether changes in individual- and county-level covariates alter older adults' risk of OUD. Moreover, we conducted race/ethnicity-specific models to compare how these associations vary across racial/ethnic groups. At the county-level, a one-unit increase in social isolation (mean = -0.197, SD = 0.511) increased the risk of OUD by 5.5 percent (OR = 1.055; 95% CI = [1.018, 1.094]) and a one-percentage-point increase in the working population employed in primary industry decreases the risk of OUD by 1 percent (OR = 0.990; 95% CI = [0.985, 0.996]). At the individual-level, increases in the Medicare Hierarchical Condition Categories risk score, physical comorbidity, and mental comorbidity all elevate the risk of OUD. The relationship between county-level social isolation and OUD is driven by non-Hispanic whites, while Hispanic beneficiaries are less sensitive to the changes in county-level factors than any other racial ethnic groups. Between 2013 and 2018, US older adults' risk of OUD was associated with both ecological and individual factors, which carries implications for intervention. Further research is needed to understand why associations of individual factors with OUD are comparable across racial/ethnic groups, but county-level social isolation is only associated with OUD among non-Hispanic white beneficiaries.

Social isolation, residential stability, and opioid use disorder among older Medicare beneficiaries: Metropolitan and non-metropolitan county comparison.

Research has shown that the prevalence of opioid use disorder (OUD) may rise substantially as society ages, but this issue receives the least attention in the literature. To address this gap, this study utilizes county-level data from multiple data sources (1) to investigate whether social isolation is associated with OUD prevalence among older Medicare beneficiaries, (2) to examine whether and how residential stability moderates the association between social isolation and OUD prevalence in US counties, and (3) to determine if there are any differences in these associations between metropolitan and non-metropolitan counties. The results show that social isolation is a significant factor for county-level OUD prevalence, regardless of metropolitan status. In addition, counties with high residential stability have low prevalence of OUD among older adults and this association is stronger in metropolitan than in non-metropolitan counties. Nonetheless, high levels of residential stability reinforce the positive relationship between social isolation and OUD prevalence. As a result, when developing policies and interventions aimed at reducing OUD among older adults, place of residence must be taken into account.

Income inequality and opioid prescribing rates: Exploring rural/urban differences in pathways via residential stability and social isolation.

While opioid prescribing rates have drawn researchers' attention, little is known about the mechanisms through which income inequality affects opioid prescribing rates and even less focuses on whether there is a rural/urban difference in mediating pathways. Applying mediation analysis techniques to a unique ZIP code level dataset from several sources maintained by the Centers for Medicare and Medicaid Services, we explicitly examine two mechanisms through residential stability and social isolation by rural/urban status and find that (1) income inequality is not directly related to opioid prescribing rates, but it exerts its influence on opioid prescribing via poor residential stability and elevated social isolation; (2) social isolation accounts for two-thirds of the mediating effect of income inequality on opioid prescribing rates among urban ZIP codes, but the proportion halves among rural ZIP codes; (3) residential stability plays a larger role in understanding how income inequality matters in rural than in urban ZIP codes; and (4) beneficiary characteristics only matter in urban ZIP codes. These findings offer nuanced insight into how income inequality affects opioid prescribing rates and suggests that the determinants of opioid prescribing rates vary by rural/urban status. Future research may benefit from identifying place-specific factors for opioid prescribing rates.

Trends in Opioid Use Disorder Among Older Adults: Analyzing Medicare Data, 2013-2018.

INTRODUCTION: Opioid use disorder has grown rapidly over the years and is a public health crisis in the U.S. Although opioid use disorder is widely studied, relatively little is known about it among older adults. The goal of this study is to gain a better understanding of opioid use disorder among older Medicare beneficiaries over time and across several sociodemographic dimensions. METHODS: Data from the 2013-2018 Centers for Medicare & Medicaid Services Master Beneficiary Summary Files were analyzed in 2020 to examine the trends in opioid use disorder prevalence among Fee-for-Service Medicare beneficiaries aged ≥65 years. Utilizing the overarching opioid use disorder flag, trends in opioid use disorder prevalence were examined for the following sociodemographic dimensions: age, sex, race/ethnicity, and dual eligibility status (i.e., enrolled in both Medicare and Medicaid owing to low income). Chi-square tests were used to compare opioid use disorder prevalence across groups. RESULTS: Since 2013, estimated rates of opioid use disorder among older adults have increased by >3-fold overall in the U.S. Estimated opioid use disorder is more prevalent among the young-old (i.e., ages 65-69 years) beneficiaries than among other older adults, and dually eligible beneficiaries have consistently shared a heavier burden of opioid use disorder than Medicare-only beneficiaries. Regarding race/ethnicity, Blacks and American Indians/Alaskan Natives are more vulnerable to opioid use disorder than other groups. CONCLUSIONS: The descriptive trends between 2013 and 2018 indicate that estimated opioid use disorder prevalence has increased greatly over the study period in all sociodemographic subgroups of older adults, highlighting an urgent challenge for public health professionals and gerontologists.

Rural/Urban Differences in the Predictors of Opioid Prescribing Rates Among Medicare Part D Beneficiaries 65 Years of Age and Older.

PURPOSE: While research has been done comparing rural/urban differences in opioid prescribing to the disabled Medicare Part D population, research on opioid prescribing among the aged Medicare Part D population is lacking. This study aims to fill this gap by exploring the predictors of opioid prescribing to aged Medicare Part D beneficiaries and investigating whether these predictors vary across rural and urban areas. METHODS: This is an analysis of ZIP Codes in the continental United States (18,126 ZIP Codes) utilizing 2017 data from Centers for Medicare & Medicaid Services. The analytic approach includes aspatial descriptive analysis, exploratory spatial analysis with geographically weighted regression, and explanatory analysis with spatial error regime modeling. FINDINGS: Both beneficiary and prescriber characteristics play an important role in determining opioid prescribing rates in urban ZIP Codes, but most of them fail to explain the opioid prescribing rates in rural ZIP Codes. CONCLUSION: We identify potential spatial nonstationarity in opioid prescribing rates, indicating the complex nature of opioid-related issues. This means that the same stimulus may not lead to the same change in opioid prescribing rates, because the change may be place specific. By understanding the rural/urban differences in the predictors of opioid prescribing, place-specific policies can be developed that can guide more informed opioid prescribing practices and necessary interventions.

Geographic variation in predictors of ED admission rates in U.S. Medicare fee-for-service beneficiaries.

INTRODUCTION: We study community-level factors associated with emergency department (ED) admission rates and assessed how they vary across geography. METHODS: We conducted an ecological study using 2012 data from 100% of U.S. Medicare Fee-for-Service beneficiaries to calculate county-level ED admission rates, adjusted by Hierarchical Condition Categories to control for patient health. We tested community-level measures related to healthcare market concentration, healthcare delivery, and socioeconomic factors potentially associated with admission rates and assessed whether these factors predicted ED admission rates across counties using ordinary least squares (OLS) regression and whether they varied across geography using geographically weighted regression (GWR). RESULTS: In 3031 U.S. counties, the ED admission rate varied from 3.9% to 82.2%. The lowest ED admission rates were concentrated in counties in Kansas, Oregon, and Vermont and the highest ED admission rates were in counties throughout Washington, Wyoming, Texas, and Colorado. The OLS model found several community-level factors that negatively impacted admission rates, specifically hospital market concentration, the rate of hospital beds with urgent care, and the rate of hospital beds. The factors that had a positive impact on the admission rate include the rate of MDs and factors for disadvantage, affluence, and foreign born/Hispanic. However, GWR showed the relationship between the ED admission rate and predictors varied across U.S. counties CONCLUSIONS: The association between healthcare market concentration, healthcare delivery, and socioeconomic factors with ED admissions differed across communities in Medicare beneficiaries. This suggests that policy and interventions to reduce ED admissions need to be tailored to specific community contexts.

County-Level Variation in Emergency Department Admission Rates Among US Medicare Beneficiaries.

STUDY OBJECTIVE: Hospital-based emergency departments (EDs) are the gateway to hospital admissions for many Americans. Approximately half of all US hospital admissions originate from EDs, and more than 3 in 4 are among Medicare beneficiaries. Recent literature has demonstrated nearly 2-fold variation in both physician- and hospital-level ED admission rates. We study geographic variation at the county level in ED admission rates among Medicare fee-for-service beneficiaries. METHODS: Using the 100% population data from the Centers for Medicare & Medicaid Services (CMS), we analyzed beneficiaries continuously enrolled in Medicare fee-for-service Parts A and B who resided in the 50 states and the District of Columbia in 2012. The ED admission rate was aggregated to the county level. ED admission rates were adjusted with the CMS Hierarchical Condition Categories (HCC) risk score. The resulting HCC adjusted ED admission rate was mapped to display the variation by county. RESULTS: The average county HCC adjusted ED admission rate was 30.8% in the Medicare population. Counties in the lowest quintile had an ED admission rate of 19.9% or lower. By comparison, counties in the highest quintile had an ED admission rate of 40.3% or higher. CONCLUSION: Among Medicare beneficiaries, county-level ED admission rates varied 2-fold between counties in the lowest and highest quintiles. Future work should focus on exploring causes for this variation, such as racial ethnic composition, socioeconomic status, and health care delivery system characteristics and the research of effectiveness of policies that affect ED admission decisions.

Exploring geographic variation in US mortality rates using a spatial Durbin approach.

Previous studies focused on identifying the determinants of mortality in US counties have examined the relationships between mortality and explanatory covariates within a county only, and have ignored the well-documented spatial dependence of mortality. We challenge earlier literature by arguing that the mortality rate of a certain county may also be associated with the features of its neighboring counties beyond its own features. Drawing from both the spillover (i.e., same direction effect) and social relativity (i.e., opposite direction effect) perspectives, our spatial Durbin modeling results indicate that both theoretical perspectives provide valuable frameworks to guide the modeling of mortality variation in US counties. Our empirical findings support that mortality rate of a certain county is associated with the features of its neighbors beyond its own features. Specifically, we found support for the spillover perspective in which the percentage of the Hispanic population, concentrated disadvantage, and the social capital of a specific county are negatively associated with the mortality rate in the specific county and also in neighboring counties. On the other hand, the following covariates fit the social relativity process: health insurance coverage, percentage of non-Hispanic other races, and income inequality. Their direction of the associations with mortality in the specific county is opposite to that of the relationships with mortality in neighboring counties. Methodologically, spatial Durbin modeling addresses the shortcomings of traditional analytic approaches used in ecological mortality research such as ordinary least squares, spatial error, and spatial lag regression. Our results produce new insights drawn from unbiased estimates.

When homogeneity meets heterogeneity: the geographically weighted regression with spatial lag approach to prenatal care utilization.

Using geographically weighted regression (GWR), a recent study by Shoff and colleagues (2012) investigated the place-specific risk factors for prenatal care utilisation in the United States of America (USA) and found that most of the relationships between late or no prenatal care and its determinants are spatially heterogeneous. However, the GWR approach may be subject to the confounding effect of spatial homogeneity. The goal of this study was to address this concern by including both spatial homogeneity and heterogeneity into the analysis. Specifically, we employed an analytic framework where a spatially lagged (SL) effect of the dependent variable is incorporated into the GWR model, which is called GWR-SL. Using this framework, we found evidence to argue that spatial homogeneity is neglected in the study by Shoff et al. (2012) and that the results change after considering the SL effect of prenatal care utilisation. The GWR-SL approach allowed us to gain a placespecific understanding of prenatal care utilisation in USA counties. In addition, we compared the GWR-SL results with the results of conventional approaches (i.e., ordinary least squares and spatial lag models) and found that GWR-SL is the preferred modelling approach. The new findings help us to better estimate how the predictors are associated with prenatal care utilisation across space, and determine whether and how the level of prenatal care utilisation in neighbouring counties matters.

Racial segregation and maternal smoking during pregnancy: a multilevel analysis using the racial segregation interaction index.

Drawing from both the place stratification and ethnic enclave perspectives, we use multilevel modeling to investigate the relationships between women's race/ethnicity (i.e., non-Hispanic white, non-Hispanic black, Asian, and Hispanic) and maternal smoking during pregnancy, and examine if these relationships are moderated by racial segregation in the continental United States. The results show that increased interaction with whites is associated with increased probability of maternal smoking during pregnancy, and racial segregation moderates the relationships between race/ethnicity and maternal smoking. Specifically, living in a less racially segregated area is related to a lower probability of smoking during pregnancy for black women, but it could double and almost triple the probability of smoking for Asian women and Hispanic women, respectively. Our findings provide empirical evidence for both the place stratification and ethnic enclave perspectives.

Spatializing health research: what we know and where we are heading.

Beyond individual-level factors, researchers have adopted a spatial perspective to explore potentially modifiable environmental determinants of health. A spatial perspective can be integrated into health research by incorporating spatial data into studies or analysing georeferenced data. Given the rapid changes in data collection methods and the complex dynamics between individuals and environment, we argue that geographical information system (GIS) functions have shortcomings with respect to analytical capability and are limited when it comes to visualizing the temporal component in spatio-temporal data. In addition, we maintain that relatively little effort has been made to handle spatial heterogeneity. To that end, health researchers should be persuaded to better justify the theoretical meaning underlying the spatial matrix in analysis, while spatial data collectors, GIS specialists, spatial analysis methodologists and the different breeds of users should be encouraged to work together making health research move forward through addressing these issues.