Association between gestational PFAS exposure and Children's adiposity in a diverse population.

Perfluoroalkyl substances (PFAS) are widely distributed suspected obesogens that cross the placenta. However, few data are available to assess potential fetal effects of PFAS exposure on children's adiposity in diverse populations. To address the data gap, we estimated associations between gestational PFAS concentrations and childhood adiposity in a diverse mother-child cohort. We considered 6 PFAS in first trimester blood plasma, measured using ultra-high-performance liquid chromatography with tandem mass spectrometry, collected from non-smoking women with low-risk singleton pregnancies (n = 803). Body mass index (BMI), waist circumference (WC), fat mass, fat-free mass, and % body fat were ascertained in 4-8 year old children as measures of adiposity. We estimated associations of individual gestational PFAS with children's adiposity and overweight/obesity, adjusted for confounders. There were more non-Hispanic Black (31.7 %) and Hispanic (42.6 %) children with overweight/obesity, than non-Hispanic white (18.2 %) and Asian/Pacific Islander (16.4 %) children (p < 0.0001). Perfluorooctane sulfonate (PFOS; 5.3 ng/mL) and perfluorooctanoic acid (2.0 ng/mL) had the highest median concentrations in maternal blood. Among women without obesity (n = 667), greater perfluoroundecanoic acid (PFUnDA) was associated with their children having higher WC z-score (ß = 0.08, 95%CI: 0.01, 0.14; p = 0.02), fat mass (ß = 0.55 kg, 95%CI: 0.21, 0.90; p = 0.002), and % body fat (ß = 0.01 %; 95%CI: 0.003, 0.01; p = 0.004), although the association of PFUnDA with fat mass attenuated at the highest concentrations. Among women without obesity, the associations of PFAS and their children's adiposity varied significantly by self-reported race-ethnicity, although the direction of the associations was inconsistent. In contrast, among the children of women with obesity, greater, PFOS, perfluorononanoic acid, and perfluorodecanoic acid concentrations were associated with less adiposity (n = 136). Our results suggest that specific PFAS may be developmental obesogens, and that maternal race-ethnicity may be an important modifier of the associations among women without obesity.

Spatial and temporal trends in social vulnerability and COVID-19 incidence and death rates in the United States.

BACKGROUND: Socially vulnerable communities may be at higher risk for COVID-19 outbreaks in the US. However, no prior studies examined temporal trends and differential effects of social vulnerability on COVID-19 incidence and death rates. Therefore, we examined temporal trends among counties with high and low social vulnerability to quantify disparities in trends over time. METHODS: We conducted a longitudinal analysis examining COVID-19 incidence and death rates from March 15 to December 31, 2020, for each US county using data from USAFacts. We classified counties using the Social Vulnerability Index (SVI), a percentile-based measure from the Centers for Disease Control and Prevention, with higher values indicating more vulnerability. Using a Bayesian hierarchical negative binomial model, we estimated daily risk ratios (RRs) comparing counties in the first (lower) and fourth (upper) SVI quartiles, adjusting for rurality, percentage in poor or fair health, percentage female, percentage of smokers, county average daily fine particulate matter (PM2.5), percentage of primary care physicians per 100,000 residents, daily temperature and precipitation, and proportion tested for COVID-19. RESULTS: At the outset of the pandemic, the most vulnerable counties had, on average, fewer cases per 100,000 than least vulnerable SVI quartile. However, on March 28, we observed a crossover effect in which the most vulnerable counties experienced higher COVID-19 incidence rates compared to the least vulnerable counties (RR = 1.05, 95% PI: 0.98, 1.12). Vulnerable counties had higher death rates starting on May 21 (RR = 1.08, 95% PI: 1.00,1.16). However, by October, this trend reversed and the most vulnerable counties had lower death rates compared to least vulnerable counties. CONCLUSIONS: The impact of COVID-19 is not static but can migrate from less vulnerable counties to more vulnerable counties and back again over time.

Propensity score matching for multilevel spatial data: accounting for geographic confounding in health disparity studies.

BACKGROUND: Diabetes is a public health burden that disproportionately affects military veterans and racial minorities. Studies of racial disparities are inherently observational, and thus may require the use of methods such as Propensity Score Analysis (PSA). While traditional PSA accounts for patient-level factors, this may not be sufficient when patients are clustered at the geographic level and thus important confounders, whether observed or unobserved, vary by geographic location. METHODS: We employ a spatial propensity score matching method to account for "geographic confounding", which occurs when the confounding factors, whether observed or unobserved, vary by geographic region. We augment the propensity score and outcome models with spatial random effects, which are assigned scaled Besag-York-Mollié priors to address spatial clustering and improve inferences by borrowing information across neighboring geographic regions. We apply this approach to a study exploring racial disparities in diabetes specialty care between non-Hispanic black and non-Hispanic white veterans. We construct multiple global estimates of the risk difference in diabetes care: a crude unadjusted estimate, an estimate based solely on patient-level matching, and an estimate that incorporates both patient and spatial information. RESULTS: In simulation we show that in the presence of an unmeasured geographic confounder, ignoring spatial heterogeneity results in increased relative bias and mean squared error, whereas incorporating spatial random effects improves inferences. In our study of racial disparities in diabetes specialty care, the crude unadjusted estimate suggests that specialty care is more prevalent among non-Hispanic blacks, while patient-level matching indicates that it is less prevalent. Hierarchical spatial matching supports the latter conclusion, with a further increase in the magnitude of the disparity. CONCLUSIONS: These results highlight the importance of accounting for spatial heterogeneity in propensity score analysis, and suggest the need for clinical care and management strategies that are culturally sensitive and racially inclusive.

Racial Disparities in Elementary School Disciplinary Actions: Findings From the ABCD Study.

OBJECTIVE: Detentions and suspensions are common practices of school discipline, despite evidence that they are largely ineffective and disproportionately affect children from racial and ethnic minority backgrounds, particularly Black children, and children of lower socioeconomic status. However, few studies have examined suspension and detention rates among race, ethnicity, and family structure (single parent versus secondary caregiver) when controlling for typical behaviors associated with detention and suspension such as externalizing symptoms, age, sex, family income, family education, family conflict, and special education needs. METHOD: Caregivers of 11,875 children between ages 9 and 10 years from the Adolescent Brain Cognitive Development (ABCD) study completed a questionnaire assessing their child's demographics, family information, emotions and behaviors, and past-year school discipline history. Data were analyzed with logistic regression, implemented with a generalized estimating equations model. RESULTS: 5.4% of children received a detention or suspension. Controlling for typical predictors of behaviors, Black and multiracial Black children had up to 3.5 times greater odds of receiving a detention or suspension than White children; there were no disciplinary differences for Hispanic or Asian children compared to White children. Children from single-parent households had 1.4 times the odds of receiving detentions or suspensions than children in homes with a secondary caregiver. CONCLUSION: Disciplinary actions that can impair typical childhood development, lead to academic failure and dropout, and cause significant emotional and psychological distress disproportionately affect Black children, multiracial Black children, and children from single-parent homes. Racism in elementary school discipline can perpetuate disparities in today's educational system.

Preschool Healthy Food Policy Did Not Increase Percent of Food Wasted: Evidence from the Carolinas.

This research evaluates the effects of a South Carolina (SC) policy, which changed the nutrition standards for foods served in early care and education (ECE) settings, on wasted food. A two-group pre-test/post-test evaluation was performed in ECE centers serving children age 3-5 from households with lower incomes in SC (n = 102 children from 34 centers, intervention) and North Carolina (NC; n = 99 children from 30 centers, comparison). Direct observation was performed to assess the quantity and kcal of food served and quantity and percent of food discarded, by food group and nutrient, enabling assessment of waste in the absence of intervention. Mixed-effects linear models were fit to estimate, by state, differences in change from baseline to post-implementation at the center level. Covariates were selected a priori, including center enrollment, racial composition, director educational attainment, years in operation, for-profit status, and Child and Adult Care Food Program (CACFP) participation. Waste of food was high across states and time points. The policy was not associated with a change in percent of food discarded in SC compared to NC in adjusted analyses.

Spatial and temporal trends in social vulnerability and COVID-19 incidence and death rates in the United States.

BACKGROUND: Emerging evidence suggests that socially vulnerable communities are at higher risk for coronavirus disease 2019 (COVID-19) outbreaks in the United States. However, no prior studies have examined temporal trends and differential effects of social vulnerability on COVID-19 incidence and death rates. The purpose of this study was to examine temporal trends among counties with high and low social vulnerability and to quantify disparities in these trends over time. We hypothesized that highly vulnerable counties would have higher incidence and death rates compared to less vulnerable counties and that this disparity would widen as the pandemic progressed. METHODS: We conducted a retrospective longitudinal analysis examining COVID-19 incidence and death rates from March 1 to August 31, 2020 for each county in the US. We obtained daily COVID-19 incident case and death data from USAFacts and the Johns Hopkins Center for Systems Science and Engineering. We classified counties using the Social Vulnerability Index (SVI), a percentile-based measure from the Centers for Disease Control and Prevention in which higher scores represent more vulnerability. Using a Bayesian hierarchical negative binomial model, we estimated daily risk ratios (RRs) comparing counties in the first (lower) and fourth (upper) SVI quartiles. We adjusted for percentage of the county designated as rural, percentage in poor or fair health, percentage of adult smokers, county average daily fine particulate matter (PM2.5), percentage of primary care physicians per 100,000 residents, and the proportion tested for COVID-19 in the state. RESULTS: In unadjusted analyses, we found that for most of March 2020, counties in the upper SVI quartile had significantly fewer cases per 100,000 than lower SVI quartile counties. However, on March 30, we observed a crossover effect in which the RR became significantly greater than 1.00 (RR = 1.10, 95% PI: 1.03, 1.18), indicating that the most vulnerable counties had, on average, higher COVID-19 incidence rates compared to least vulnerable counties. Upper SVI quartile counties had higher death rates on average starting on March 30 (RR = 1.17, 95% PI: 1.01,1.36). The death rate RR achieved a maximum value on July 29 (RR = 3.22, 95% PI: 2.91, 3.58), indicating that most vulnerable counties had, on average, 3.22 times more deaths per million than the least vulnerable counties. However, by late August, the lower quartile started to catch up to the upper quartile. In adjusted models, the RRs were attenuated for both incidence cases and deaths, indicating that the adjustment variables partially explained the associations. We also found positive associations between COVID-19 cases and deaths and percentage of the county designated as rural, percentage of resident in fair or poor health, and average daily PM2.5. CONCLUSIONS: Results indicate that the impact of COVID-19 is not static but can migrate from less vulnerable counties to more vulnerable counties over time. This highlights the importance of protecting vulnerable populations as the pandemic unfolds.

Household Food Security and Infant Adiposity.

OBJECTIVES: Food insecurity has been associated with obesity, but previous studies are inconsistent and few included infants. We examined associations between household food security and infant adiposity and assessed the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) and Supplemental Nutrition Assistance Program (SNAP) as effect modifiers. We hypothesized that infants from food-insecure households would have greater adiposity, with attenuation by WIC and SNAP. METHODS: We repeatedly measured 666 infants from the southeastern United States in 2013-2017. We categorized households as high, marginal, low, or very low using the US Household Food Security Survey Module. Outcomes were BMI z score, subscapular and triceps skinfold-for-age z score, the sum of subscapular and triceps skinfolds, the ratio of subscapular and triceps skinfolds, and BMI z score ≥1 (at risk for overweight). We used covariate-adjusted repeated-measures linear and logistic regressions. RESULTS: Of infants, 68.6% were Black and 60.5% had household incomes <$20 000. Interactions between food security and WIC and/or SNAP were not significant. Compared with infants from high food security households, infants from very low food security households had higher BMI z scores (0.18 U; 95% confidence interval [CI] 0.01 to 0.35), higher subscapular skinfold-for-age z scores (0.31 U; 95% CI 0.04 to 0.59), a higher sum of subscapular and triceps skinfolds (0.53 mm; 95% CI 0.002 to 1.07), and greater odds of being at risk for overweight (odds ratio 1.55; 95% CI 1.14 to 2.10). Infants from low food security households had greater odds of being at risk for overweight (odds ratio 1.72; 95% CI 1.17 to 2.10). CONCLUSIONS: In larger and longer studies, researchers should examine food security and adiposity in young children.

Geographic and Racial/Ethnic Variation in Glycemic Control and Treatment in a National Sample of Veterans With Diabetes.

OBJECTIVE: Geographic and racial/ethnic disparities related to diabetes control and treatment have not previously been examined at the national level. RESEARCH DESIGN AND METHODS: A retrospective cohort study was conducted in a national cohort of 1,140,634 veterans with diabetes, defined as two or more diabetes ICD-9 codes (250.xx) across inpatient and outpatient records. Main exposures of interest included 125 Veterans Administration Medical Center (VAMC) catchment areas as well as racial/ethnic group. The main outcome measure was HbA1c level dichotomized at ≥8.0% (≥64 mmol/mol). RESULTS: After adjustment for age, sex, racial/ethnic group, service-connected disability, marital status, and the van Walraven Elixhauser comorbidity score, the prevalence of uncontrolled diabetes varied by VAMC catchment area, with values ranging from 19.1% to 29.2%. Moreover, these differences largely persisted after further adjusting for medication use and adherence as well as utilization and access metrics. Racial/ethnic differences in diabetes control were also noted. In our final models, compared with non-Hispanic Whites, non-Hispanic Blacks (odds ratio 1.11 [95% credible interval 1.09-1.14]) and Hispanics (1.36 [1.09-1.14]) had a higher odds of uncontrolled HBA1c level. CONCLUSIONS: In a national cohort of veterans with diabetes, we found geographic as well as racial/ethnic differences in diabetes control rates that were not explained by adjustment for demographics, comorbidity burden, use or type of diabetes medication, health care utilization, access metrics, or medication adherence. Moreover, disparities in suboptimal control appeared consistent across most, but not all, VAMC catchment areas, with non-Hispanic Black and Hispanic veterans having a higher odds of suboptimal diabetes control than non-Hispanic White veterans.

Healthy Eating Policy Improves Children's Diet Quality in Early Care and Education in South Carolina.

Policies to promote healthy foods in early care and education (ECE) in the United States exist, but few have been prospectively evaluated. In South Carolina, a statewide program serving low-income children in ECE enacted new policies promoting healthy foods. We conducted an evaluation to measure changes in dietary intake among children in ECE exposed and not exposed to the new policy. Using direct observation, we assessed dietary intake in 112 children from 34 ECE centers in South Carolina and 90 children from 30 ECE centers in North Carolina (a state with no policy). We calculated Healthy Eating Index-2015 (HEI) scores to measure diet quality consumed before and after the policy was enacted. We fit mixed-effects linear models to estimate differences in HEI scores by state from baseline to post-policy, adjusting for child race, number of children enrolled, director education, center years in operation, participation in the Child and Adult Care Food Program (CACFP), and center profit status. The policy increased HEI scores for whole fruits, total fruits, and lean proteins, but decreased scores for dairy. Thus, the policy was associated with some enhancements in dietary intake, but additional support may help improve other components of diet.

Participation in the Child and Adult Care Food Program is associated with fewer barriers to serving healthier foods in early care and education.

BACKGROUND: Early care and education (ECE) is an important setting for influencing young children's dietary intake. There are several factors associated with barriers to healthy eating in ECE, and recent evidence suggests that participation in the Child and Adult Care Food Program (CACFP), the primary national food assistance program in ECE, may be associated with fewer barriers to serving healthier foods. However, no prior studies have examined differences between CACFP participants and non-participants across a large, multi-state sample. This is the first study to examine the association between CACFP participation and barriers to serving healthier foods in ECE using a random sample of directors from two regions across the country. METHODS: We conducted a cross-sectional survey among a random sample of child care center directors from four states (Massachusetts, North Carolina, Rhode Island, and South Carolina). We conducted logistic and Poisson regression to calculate the odds and incidence rate ratios of reporting 1) no barriers, 2) specific barriers (e.g., cost), and 3) the total number of barriers, by CACFP status, adjusting for covariates of interest. RESULTS: We received 713 surveys (36% response rate). About half (55%) of centers participated in CACFP. The most prevalent reported barriers to serving healthier foods were cost (42%) and children's food preferences (19%). Directors from CACFP centers were twice as likely to report no barriers, compared to directors from non-CACFP centers (OR 2.03; 95% CI [1.36, 3.04]; p < 0.01). Directors from CACFP centers were less likely to report cost as a barrier (OR = 0.46; 95% [CI 0.31, 0.67]; p < 0.001), and reported fewer barriers overall (IRR = 0.77; 95% CI [0.64, 0.92]; p < 0.01), compared to directors from non-CACFP centers. CONCLUSIONS: CACFP directors reported fewer barriers to serving healthier foods in child care centers. Still, cost and children's food preferences are persistent barriers to serving healthier foods in ECE. Future research should evaluate characteristics of CACFP participation that may alleviate these barriers, and whether barriers emerge or persist following 2017 rule changes to CACFP nutrition standards.

Reported Neighborhood Traffic and the Odds of Asthma/Asthma-Like Symptoms: A Cross-Sectional Analysis of a Multi-Racial Cohort of Children.

Asthma in children poses a significant clinical and public health burden. We examined the association between reported neighborhood traffic (a proxy for traffic-related air pollution) and asthma among 855 multi-racial children aged 4-8 years old who participated in the Environmental Influences on Child Health Outcomes (ECHO) cohort. We hypothesized that high neighborhood traffic density would be associated with the prevalence of asthma. Asthma/asthma-like symptoms (defined as current and/or past physician diagnosed asthma, past wheezing, or nighttime cough or wheezing in the past 12 months) was assessed by parental report. The relationship between neighborhood traffic and asthma/asthma-like symptoms was assessed using logistic regression. The prevalence of asthma/asthma-like symptoms among study participants was 23%, and 15% had high neighborhood traffic. Children with significant neighborhood traffic had a higher odds of having asthma/asthma-like symptoms than children without neighborhood traffic [adjusted OR = 2.01 (95% CI: 1.12, 3.62)] after controlling for child's race-ethnicity, age, sex, maternal education, family history of asthma, play equipment in the home environment, public parks, obesity and prescribed asthma medication. Further characterization of neighborhood traffic is needed since many children live near high traffic zones and significant racial/ethnic disparities exist.

Addressing geographic confounding through spatial propensity scores: a study of racial disparities in diabetes.

Motivated by a study exploring differences in glycemic control between non-Hispanic black and non-Hispanic white veterans with type 2 diabetes, we aim to address a type of confounding that arises in spatially referenced observational studies. Specifically, we develop a spatial doubly robust propensity score estimator to reduce bias associated with geographic confounding, which occurs when measured or unmeasured confounding factors vary by geographic location, leading to imbalanced group comparisons. We augment the doubly robust estimator with spatial random effects, which are assigned conditionally autoregressive priors to improve inferences by borrowing information across neighboring geographic regions. Through a series of simulations, we show that ignoring spatial variation results in increased absolute bias and mean squared error, while the spatial doubly robust estimator performs well under various levels of spatial heterogeneity and moderate sample sizes. In the motivating application, we construct three global estimates of the risk difference between race groups: an unadjusted estimate, a doubly robust estimate that adjusts only for patient-level information, and a hierarchical spatial doubly robust estimate. Results indicate a gradual reduction in the risk difference at each stage, with the inclusion of spatial random effects providing a 20% reduction compared to an estimate that ignores spatial heterogeneity. Smoothed maps indicate poor glycemic control across Alabama and southern Georgia, areas comprising the so-called "stroke belt." These results suggest the need for community-specific interventions to target diabetes in geographic areas of greatest need.

Barriers and Facilitators to Compliance with a State Healthy Eating Policy in Early Care and Education Centers.

BACKGROUND: Early care and education (ECE) policies can improve childhood obesity risk factors. We evaluated barriers and facilitators to implementing mandatory nutrition standards for foods provided in South Carolina ECE centers serving low-income children, comparing centers participating in the Child and Adult Care Food Program (CACFP) with non-CACFP centers. METHODS: We mailed 261 surveys (demographics, policies and practices, barriers and facilitators) to center directors after new state nutrition standards were implemented in South Carolina. We conducted univariate and bivariate analyses to explore relationships between barriers, facilitators, and center-level characteristics, by CACFP status. RESULTS: We received 163 surveys (62% response rate). Centers had a median [interquartile range (IQR)] of 5 (4-7) classrooms and 59 (37.5-89) total children enrolled. More than half (60.1%) of directors reported they were moderately or fully informed about the standards. The most common barriers were food costs (17.8%) and children's food preferences (17.8%). More non-CACFP directors reported food costs as a barrier (28.6% vs. 6.5%, p < 0.001), having to spend additional money on healthier foods (48.8% vs. 28.6%, p = 0.01), and having to provide additional nutrition education to parents (28.6% vs. 11.7%, p = 0.01), compared with CACFP directors. CONCLUSIONS: Center directors were generally well informed about the nutrition standards. The most common barriers to implementing the standards were food costs and children's food preferences. Centers participating in CACFP may be in a better position to adhere to new state nutrition standards, as they receive some federal reimbursement for serving healthy foods and may be more accustomed to regulation.

State Regulations Promoting Infant Physical Activity in Early Care and Education.

BACKGROUND: State policies have the potential to improve early care and education (ECE) settings, but little is known about the extent to which states are updating their licensing and administrative regulations, especially in response to national calls to action. In 2013, we assessed state regulations promoting infant physical activity in ECE and compared them with national recommendations. To assess change over time, we conducted this review again in 2018. METHODS: We reviewed regulations for all US states for child care centers (centers) and family child care homes (homes) and compared them with three national recommendations: (1) provide daily tummy time; (2) use cribs, car seats, and high chairs for their primary purpose; and (3) limit the use of restrictive equipment (e.g., strollers). We performed exact McNemar's tests to compare the number of states meeting recommendations from 2013 to 2018 to evaluate whether states had made changes over this period. RESULTS: From 2013 to 2018, we observed significant improvement in one recommendation for homes-to use cribs, car seats, and high chairs for their primary purpose (odds ratio 11.0; 95% CI 1.6-47.3; p = 0.006). We did not observe any other significant difference between 2013 and 2018 regulations. CONCLUSIONS: Despite increased awareness of the importance of early-life physical activity, we observed only modest improvement in the number of states meeting infant physical activity recommendations over the past 5 years. In practice, ECE programs may be promoting infant physical activity, but may not be required to do so through state regulations.

A marginalized two-part model for longitudinal semicontinuous data.

In health services research, it is common to encounter semicontinuous data, characterized by a point mass at zero followed by a right-skewed continuous distribution with positive support. Examples include health expenditures, in which the zeros represent a subpopulation of patients who do not use health services, while the continuous distribution describes the level of expenditures among health services users. Longitudinal semicontinuous data are typically analyzed using two-part random-effect mixtures with one component that models the probability of health services use, and a second component that models the distribution of log-scale positive expenditures among users. However, because the second part conditions on a non-zero response, obtaining interpretable effects of covariates on the combined population of health services users and non-users is not straightforward, even though this is often of greatest interest to investigators. Here, we propose a marginalized two-part model for longitudinal data that allows investigators to obtain the effect of covariates on the overall population mean. The model additionally provides estimates of the overall population mean on the original, untransformed scale, and many covariates take a dual population average and subject-specific interpretation. Using a Bayesian estimation approach, this model maintains the flexibility to include complex random-effect structures and easily estimate functions of the overall mean. We illustrate this approach by evaluating the effect of a copayment increase on health care expenditures in the Veterans Affairs health care system over a four-year period.

Effects of a New State Policy on Physical Activity Practices in Child Care Centers in South Carolina.

OBJECTIVES: We sought to determine the extent to which child care centers in South Carolina improved physical activity practices after a new policy took effect. METHODS: In 2012, South Carolina adopted new mandatory physical activity standards within its child care quality enhancement program. This quasi-experimental study used North Carolina, a state not making policy changes, as the comparison. Participants were 34 child care centers in South Carolina and 30 centers in North Carolina. Researchers used the Environment and Policy Assessment and Observation (EPAO) tool to conduct center observations before and after policy implementation and then conducted repeated-measures linear regression with interaction between state and time for the Physical Activity Environment Total Score and the 8 subscale scores. RESULTS: Compared with centers in North Carolina, EPAO subscale scores in South Carolina centers increased significantly for the Fixed Play Environment (P < .001) and Physical Activity Training and Education (P = .015). The state-by-time interaction of Physical Activity Environment Total Score approached statistical significance (P = .06). CONCLUSIONS: Adoption of new physical activity standards in South Carolina child care centers was associated with improvements in practices aimed at increasing children's physical activity.

Modeling zero-modified count and semicontinuous data in health services research part 2: case studies.

This article is the second installment of a two-part tutorial on the analysis of zero-modified count and semicontinuous data. Part 1, which appears as a companion piece in this issue of Statistics in Medicine, provides a general background and overview of the topic, with particular emphasis on applications to health services research. Here, we present three case studies highlighting various approaches for the analysis of zero-modified data. The first case study describes methods for analyzing zero-inflated longitudinal count data. Case study 2 considers the use of hurdle models for the analysis of spatiotemporal count data. The third case study discusses an application of marginalized two-part models to the analysis of semicontinuous health expenditure data. Copyright © 2016 John Wiley & Sons, Ltd.

Open-label randomized trial of titrated disease management for patients with hypertension: Study design and baseline sample characteristics.

Despite the availability of efficacious treatments, only half of patients with hypertension achieve adequate blood pressure (BP) control. This paper describes the protocol and baseline subject characteristics of a 2-arm, 18-month randomized clinical trial of titrated disease management (TDM) for patients with pharmaceutically-treated hypertension for whom systolic blood pressure (SBP) is not controlled (≥140mmHg for non-diabetic or ≥130mmHg for diabetic patients). The trial is being conducted among patients of four clinic locations associated with a Veterans Affairs Medical Center. An intervention arm has a TDM strategy in which patients' hypertension control at baseline, 6, and 12months determines the resource intensity of disease management. Intensity levels include: a low-intensity strategy utilizing a licensed practical nurse to provide bi-monthly, non-tailored behavioral support calls to patients whose SBP comes under control; medium-intensity strategy utilizing a registered nurse to provide monthly tailored behavioral support telephone calls plus home BP monitoring; and high-intensity strategy utilizing a pharmacist to provide monthly tailored behavioral support telephone calls, home BP monitoring, and pharmacist-directed medication management. Control arm patients receive the low-intensity strategy regardless of BP control. The primary outcome is SBP. There are 385 randomized (192 intervention; 193 control) veterans that are predominately older (mean age 63.5years) men (92.5%). 61.8% are African American, and the mean baseline SBP for all subjects is 143.6mmHg. This trial will determine if a disease management program that is titrated by matching the intensity of resources to patients' BP control leads to superior outcomes compared to a low-intensity management strategy.

Using pay for performance incentives (P4P) to improve management of suspected malaria fevers in rural Kenya: a cluster randomized controlled trial.

BACKGROUND: Inappropriate treatment of non-malaria fevers with artemisinin-based combination therapies (ACTs) is a growing concern, particularly in light of emerging artemisinin resistance, but it is a behavior that has proven difficult to change. Pay for performance (P4P) programs have generated interest as a mechanism to improve health service delivery and accountability in resource-constrained health systems. However, there has been little experimental evidence to establish the effectiveness of P4P in developing countries. We tested a P4P strategy that emphasized parasitological diagnosis and appropriate treatment of suspected malaria, in particular reduction of unnecessary consumption of ACTs. METHODS: A random sample of 18 health centers was selected and received a refresher workshop on malaria case management. Pre-intervention baseline data was collected from August to September 2012. Facilities were subsequently randomized to either the comparison (n = 9) or intervention arm (n = 9). Between October 2012 and November 2013, facilities in the intervention arm received quarterly incentive payments based on seven performance indicators. Incentives were for use by facilities rather than as payments to individual providers. All non-pregnant patients older than 1 year of age who presented to a participating facility and received either a malaria test or artemether-lumefantrine (AL) were eligible to be included in the analysis. Our primary outcome was prescription of AL to patients with a negative malaria diagnostic test (n = 11,953). Our secondary outcomes were prescription of AL to patients with laboratory-confirmed malaria (n = 2,993) and prescription of AL to patients without a malaria diagnostic test (analyzed at the cluster level, n = 178 facility-months). RESULTS: In the final quarter of the intervention period, the proportion of malaria-negative patients in the intervention arm who received AL was lower than in the comparison arm (7.3% versus 10.9%). The improvement from baseline to quarter 4 in the intervention arm was nearly three times that of the comparison arm (ratio of adjusted odds ratios for baseline to quarter 4 = 0.36, 95% CI: 0.24-0.57). The rate of prescription of AL to patients without a test was five times lower in the intervention arm (adjusted incidence rate ratio = 0.18, 95% CI: 0.07-0.48). Prescription of AL to patients with confirmed infection was not significantly different between the groups over the study period. CONCLUSIONS: Facility-based incentives coupled with training may be more effective than training alone and could complement other quality improvement approaches. TRIAL REGISTRATION: This study was registered with ClinicalTrials.gov (NCT01809873) on 11 March 2013.