Social determinants of health and disease in companion dogs: a cohort study from the Dog Aging Project.

Exposure to social environmental adversity is associated with health and survival across many social species, including humans. However, little is known about how these health and mortality effects vary across the lifespan and may be differentially impacted by various components of the environment. Here, we leveraged a relatively new and powerful model for human aging, the companion dog, to investigate which components of the social environment are associated with dog health and how these associations vary across the lifespan. We drew on comprehensive survey data collected on 21,410 dogs from the Dog Aging Project and identified five factors that together explained 33.7% of the variation in a dog's social environment. Factors capturing financial and household adversity were associated with poorer health and lower physical mobility in companion dogs, while factors that captured social support, such as living with other dogs, were associated with better health when controlling for dog age and weight. Notably, the effects of each environmental component were not equal: the effect of social support was 5× stronger than financial factors. The strength of these associations depended on the age of the dog, including a stronger relationship between the owner's age and the dog's health in younger as compared to older dogs. Taken together, these findings suggest the importance of income, stability and owner's age on owner-reported health outcomes in companion dogs and point to potential behavioral and/or environmental modifiers that can be used to promote healthy aging across species.

Associations between Neighborhood Disadvantage and Dog Walking among Participants in the Dog Aging Project.

Although neighborhood socioeconomic disadvantage is negatively related to overall physical activity, prior studies reveal a complex relationship between disadvantage and particular walking behaviors. While disadvantage is associated with reduced recreational walking through a hypothesized "fear-of-crime" mechanism, the built environment in disadvantaged neighborhoods may encourage utilitarian walking. To date, no study has assessed how disadvantage relates to dog walking, a distinct walking behavior that is neither strictly recreational nor utilitarian but represents a key mechanism through which pet ownership may affect human health. We employ a large (n = 19,732) dataset from the Dog Aging Project to understand how neighborhood disadvantage is associated with dog walking when controlling for individual-, household-, and environmental-level factors. We find that dog owners in more disadvantaged neighborhoods report less on-leash walking activity compared to owners in advantaged neighborhoods and discuss the possibility of a fear-of-crime mechanism underlying this association. These findings improve our understanding of the relationship between neighborhood disadvantage and physical function and highlight the need for public health interventions that encourage dog ownership to consider neighborhood disadvantage.

Characteristics associated with HIV and hepatitis C seroprevalence among sexual and injecting partners of HIV positive persons who inject drugs in Nairobi and coastal Kenya.

BACKGROUND: Persons who inject drugs (PWID) have higher HIV and hepatitis C virus (HCV) seroprevalence than the general population in many parts of sub-Saharan Africa (SSA). The seroprevalences of HIV and HCV are also higher in coastal Kenya than in Nairobi. Understanding drivers of regional HIV and HCV variation among PWID in Kenya may inform population-specific prevention interventions. METHODS: Using a cross-sectional study, we defined HIV and HCV seroprevalence among persons identified as sexual or injecting partners of HIV positive PWID in two regions of Kenya and used logistic regression to identify demographic and behavioral characteristics associated with higher seroprevalence. RESULTS: Among 2386 partners, 469 (19.7%) tested HIV positive and 297(12.4%) tested HCV antibody positive. Partners on the Coast were more likely to live with HIV (seroprevalences: Coast = 23.8%, Nairobi = 17.1%; p < 0.001) and be HCV antibody positive (seroprevalences: Coast = 17.0%, Nairobi = 8.6%; p < 0.001). After adjusting for sex, age, and years injecting and accounting for clustering by site, the higher prevalence of both diseases in the Coast remained significant for HIV (OR 1.68, 95% CI 1.13-2.51) but not for HCV (OR 1.72, 95% CI 0.84-3.74). Compared to those recruited in Nairobi, partners on the Coast were older (Coast = 35 years, Nairobi = 31 years; p < 0.001), more likely to be male (Coast = 77.6%, Nairobi = 61.7%; p < 0.001), to have paid (Coast = 59.2%, Nairobi = 32.8%; p < 0.001) or received (Coast = 44.2%, Nairobi 35.4%; p < 0.001) money for sex, or to have had sex with someone they knew to be HIV positive (Coast 22.0%, Nairobi 10.8%; p < 0.001). Partners who had injected for five or more years had 1.48 times greater odds (95% CI 1.20-1.82) of living with HIV compared to partners who injected less than 5 years and more than twice the odds of HCV (95% CI 1.84-4.11). CONCLUSION: HIV and HCV seroprevalence among sexual and injecting partners of PWID was, respectively, 5 times and > 12 times greater than is reported among the general population in Kenya (4% and < 1%, respectively). Providing resources and education will be crucial to reduce exposure and to maintain the lower needle and equipment sharing that we observed compared to other studies.

Veterinary Big Data: When Data Goes to the Dogs.

Dogs provide an ideal model for study as they have the most phenotypic diversity and known naturally occurring diseases of all non-human land mammals. Thus, data related to dog health present many opportunities to discover insights into health and disease outcomes. Here, we describe several sources of veterinary medical big data that can be used in research. These sources include medical records from primary medical care centers or referral hospitals, medical claims data from animal insurance companies, and datasets constructed specifically for research purposes. No data source provides information that is without limitations, but large-scale, prospective, longitudinally collected data from dog populations are ideal for further research as they offer many advantages over other data sources.

Peer-mediated HIV assisted partner services to identify and link to care HIV-positive and HCV-positive people who inject drugs: a cohort study protocol.

INTRODUCTION: Targeted, tailored interventions to test high-risk individuals for HIV and hepatitis C virus (HCV) are vital to achieving HIV control and HCV microelimination in Africa. Compared with the general population, people who inject drugs (PWID) are at increased risk of HIV and HCV and are less likely to be tested or successfully treated. Assisted partner services (APS) increases HIV testing among partners of people living with HIV and improves case finding and linkage to care. We describe a study in Kenya examining whether APS can be adapted to find, test and link to HIV care the partners of HIV-positive PWID using a network of community-embedded peer educators (PEs). Our study also identifies HCV-positive partners and uses phylogenetic analysis to determine risk factors for onward transmission of both viruses. METHODS: This prospective cohort study leverages a network of PEs to identify 1000 HIV-positive PWID for enrolment as index participants. Each index completes a questionnaire and provides names and contact information of all sexual and injecting partners during the previous 3 years. PEs then use a stepwise locator protocol to engage partners in the community and bring them to study sites for enrolment, questionnaire completion and rapid HIV and HCV testing. Outcomes include number and type of partners per index who are mentioned, enrolled, tested, diagnosed with HIV and HCV and linked to care. ETHICS AND DISSEMINATION: Potential index participants are screened for intimate partner violence (IPV) and those at high risk are not eligible to enrol. Those at medium risk are monitored for IPV following enrolment. A community advisory board engages in feedback and discussion between the community and the research team. A safety monitoring board discusses study progress and reviews data, including IPV monitoring data. Dissemination plans include presentations at quarterly Ministry of Health meetings, local and international conferences and publications. TRIAL REGISTRATION NUMBER: NCT03447210, Pre-results stage.

Predictors of First-Time and Repeat HIV Testing Among HIV-Positive Individuals in Kenya.

BACKGROUND: Despite a doubling of HIV testing coverage in Kenya over the past decade, approximately 2 in 10 people with HIV remained unaware of their infection in 2018. HIV testing is most effective in identifying people with undiagnosed HIV through frequent and strategic testing in populations at high risk. An assessment of testing frequency and predictors of first-time and repeat testing is critical for monitoring effectiveness of testing strategies. METHODS: We conducted a cross-sectional analysis of adults aged ≥18 years who tested HIV-positive at 4 HIV testing and counseling clinics in Kenya from February 2015 to February 2016. We categorized individuals based on testing history, used Wilcoxon rank-sum tests to assess differences in intervals between the most recent and current HIV test, and used log-binomial regression to determine characteristics associated with first-time and repeat testing. RESULTS: Among 1136 people testing HIV-positive, 336 (30%) had never tested before and 800 (70%) had, of whom 208 (26%) had previously tested positive. Among previously negative repeat testers, the median intertest interval was 414 days in key/priority populations (interquartile range = 179-1072) vs. 538 in the general population (interquartile range = 228-1299) (P = 0.09). Compared with previously negative repeat testers, being a first-time tester was associated with being age ≥40 years [vs. 18-24; adjusted risk ratio = 1.67, 95% confidence interval (CI): 1.23 to 2.26], men (vs. women; adjusted risk ratio = 1.45, 95% CI: 1.21 to 1.71), and testing through provider-initiated testing and counseling (vs. client initiated; 1.19, 95% CI: 1.00 to 1.40). CONCLUSIONS: There is a need to increase HIV testing among older individuals and men, increase testing frequency in key/priority populations, and maintain provider-initiated and facility-based testing to reach first-time testers.

Cardiffians' perceptions of English in the UK.

This Perceptual Dialectology (PD) study asked residents of Cardiff, Wales, about their perceptions of English in the United Kingdom (UK). In addition, because face to face exposure to dialect variation has rarely been included as a variable in PD studies, participants were asked about their travel experience to ascertain whether this might influence their responses to a PD map task. Participants' responses to the map task were analyzed using ArcGIS to create composite maps. Results show that these Cardiffians perceive "dialect or regional" speech boundaries to be located around major cities in England and Wales but also southwest Wales. Composite maps and polygon counts suggest that the more traveled respondents have a more nuanced perception of dialect regions than those who claim to travel less, suggesting that travel experience may influence PD participants' responses to map tasks.

Feasibility and acceptability of an iris biometric system for unique patient identification in routine HIV services in Kenya.

BACKGROUND: Use of routine HIV programme data for surveillance is often limited due to inaccuracies associated with patient misclassification which can be addressed by unique patient identification.We assessed the feasibility and acceptability of integrating an iris recognition biometric identification system into routine HIV care services at 4 sites in Kenya. METHODS: Patients who had recently tested HIV-positive or were engaged in care were enrolled. Images of the iris were captured using a dual-iris camera connected to a laptop. A prototype iris biometric identification system networked across the sites, analysed the iris patterns; created a template from those patterns; and generated a 12-digit ID number based on the template. During subsequent visits, the patients' irises were re-scanned, and the pattern was matched to stored templates to retrieve the ID number. RESULTS: Over 55 weeks 8,614 (98%) of 8,794 new patients were assigned a unique ID on their first visit. Among 6,078 return visits, the system correctly re-identified patients' IDs 5,234 times (86%). The false match rate (a new patient given the ID of another patient) was 0·5% while the generalized false reject rate (re-scans assigned a new ID) was 4·7%. Overall, 9 (0·1%) agreed to enrol but declined to have an iris scan. The most common reasons cited for declining an iris scan were concerns about privacy and confidentiality. CONCLUSION: Implementation of an iris recognition system in routine health information systems is feasible and highly acceptable as part of routine care in Kenya. Scale-up could improve unique patient identification and tracking, enhancing disease surveillance activities.

Index participant characteristics and HIV assisted partner services efficacy in Kenya: results of a cluster randomized trial.

INTRODUCTION: We have previously demonstrated that assisted partner services (aPS) increases HIV testing and case finding among partners of persons living with HIV (PLHIV) in a cluster randomized trial in Kenya. However, the efficacy of aPS may vary across populations. In this analysis, we explore differences in aPS efficacy by characteristics of index participants. METHODS: Eighteen HIV testing sites were randomized to immediate versus 6-week delayed aPS. Participants were PLHIV (or index participants) and their sexual partners. Partners of index participants were contacted for HIV testing and linked to care if HIV positive. Primary outcomes were the number of partners per index participant who: 1) tested for HIV, 2) tested HIV positive and 3) enrolled in HIV care. We used generalized estimating equations to assess differences in aPS efficacy by region, testing location, gender, age and knowledge of HIV status. RESULTS: From 2013 to 2015, the study enrolled 1119 index participants, 625 of whom were in the immediate group. These index participants named 1286 sexual partners. Immediate aPS was more efficacious than delayed aPS in promoting HIV testing among partners in high compared to low HIV prevalence regions (Nyanza incidence rate ratio (IRR) 7.2; 95% confidence interval (CI) 5.4, 9.6 vs. Nairobi/Central IRR 3.4 95% CI 2.3, 4.8). Higher rates of partner HIV testing were also observed for index participants in rural/peri-urban compared to urban sites (IRR 6.6; 95% CI 4.5, 9.6 vs. IRR 3.5 95% CI 2.5, 5.0 respectively), for female versus male index participants (IRR 5.8 95% CI 4.2, 7.9 vs. IRR 3.7; 95% CI 2.4, 5.8 respectively) and for newly diagnosed versus known HIV-positive index participants (IRR 6.0 95% CI 4.2, 8.7 vs. IRR 3.3; 95% CI 2.0, 7.7 respectively). Providing aPS to female versus male index participants also had a significantly higher HIV case finding rate (IRR 9.1; 95% CI 4.0, 20.9 vs. IRR 3.2 95% CI 1.7, 6.0 respectively.) CONCLUSIONS: While it is known that aPS promotes increases in HIV testing and case finding, this is the first study to demonstrate significant differences in aPS efficacy across characteristics of the index participant. Understanding these differences and their drivers will be critical as aPS is brought to scale in order to ensure all PLHIV have access to these services.

Improving Information and Communications Technology (ICT) Knowledge and Skills to Develop Health Research Capacity in Kenya.

Objectives Information and communication technology (ICT) tools are increasingly important for clinical care and international research. Many technologies would be particularly useful for healthcare workers in resource-limited settings; however, these individuals are the least likely to utilize ICT tools due tolack of knowledge and skills necessary to use them. Our program aimed to train researchers in low-resource settings on using ICT tools and to understand how different didactic modalities build knowledge and skills in this area. Methods We conducted a tiered, blended learning program for researchers in Kenya on three areas of ICT: geographic information systems, data management, and communication tools. Each course included three tiers: online courses, skills workshops, and mentored projects. Concurrently, a training of trainers course was taught to ensure sustainable ongoing training. A mixed qualitative and quantitative survey was conducted at the end of each training to assess knowledge and skill acquisition. Results Course elements that incorporated local examples and hands-on skill building activities were most valuable. Discussion boards were sometimes distracting, depending on multiple factors. Mentored projects were most useful when there were clear expectations, pre-existing projects, and clear timelines. Discussion Training in the use of ICT tools is highly valued among researchers in low-income settings, particularly when it includes hands-on skill-building and local examples. Our students demonstrated acquisition of new skills and felt these skills to be valuable in their workplaces. Conclusions Further training in ICT skills should be considered in other low-resource settings using our program as a foundational model.

Dental therapists linked to improved dental outcomes for Alaska Native communities in the Yukon-Kuskokwim Delta.

OBJECTIVES: Dental Health Aide Therapists (DHATs) have been part of the dental workforce in Alaska's Yukon-Kuskokwim (YK) Delta since 2006. They are trained to provide preventive and restorative care such as filling and extractions. In this study, we evaluated community-level dental outcomes associated with DHATs. METHODS: This was a secondary data analysis of Alaska Medicaid and electronic health record data for individuals in Alaska's YK Delta (2006-2015). The independent variable was the number of DHAT treatment days in each community. Child outcomes were preventive care, extractions, and general anesthesia. Adult outcomes were preventive care and extractions. We estimated Spearman partial correlation coefficients to test our hypotheses that increased DHAT treatment days would be associated with larger proportions utilizing preventive care and smaller proportions receiving extractions at the community-level. RESULTS: DHAT treatment days were positively associated with preventive care utilization and negatively associated with extractions for children and adults (P < 0.0001). DHAT treatment days were not associated with increased dental treatment under general anesthesia for children. CONCLUSIONS: Dental therapists are associated with more preventive care and fewer extractions. State-level policies should consider dental therapists as part of a comprehensive solution to meet the dental care needs of individuals in underserved communities and help achieve health equity and social justice.

Weather-Related Hazards and Population Change: A Study of Hurricanes and Tropical Storms in the United States, 1980-2012.

Environmental determinists predict that people move away from places experiencing frequent weather hazards, yet some of these areas have rapidly growing populations. This analysis examines the relationship between weather events and population change in all U.S. counties that experienced hurricanes and tropical storms between 1980 and 2012. Our database allows for more generalizable conclusions by accounting for heterogeneity in current and past hurricane events and losses and past population trends. We find that hurricanes and tropical storms affect future population growth only in counties with growing, high-density populations, which are only 2 percent of all counties. In those counties, current year hurricane events and related losses suppress future population growth, although cumulative hurricane-related losses actually elevate population growth. Low-density counties and counties with stable or declining populations experience no effect of these weather events. Our analysis provides a methodologically informed explanation for contradictory findings in prior studies.

Measures of Human Mobility Using Mobile Phone Records Enhanced with GIS Data.

In the past decade, large scale mobile phone data have become available for the study of human movement patterns. These data hold an immense promise for understanding human behavior on a vast scale, and with a precision and accuracy never before possible with censuses, surveys or other existing data collection techniques. There is already a significant body of literature that has made key inroads into understanding human mobility using this exciting new data source, and there have been several different measures of mobility used. However, existing mobile phone based mobility measures are inconsistent, inaccurate, and confounded with social characteristics of local context. New measures would best be developed immediately as they will influence future studies of mobility using mobile phone data. In this article, we do exactly this. We discuss problems with existing mobile phone based measures of mobility and describe new methods for measuring mobility that address these concerns. Our measures of mobility, which incorporate both mobile phone records and detailed GIS data, are designed to address the spatial nature of human mobility, to remain independent of social characteristics of context, and to be comparable across geographic regions and time. We also contribute a discussion of the variety of uses for these new measures in developing a better understanding of how human mobility influences micro-level human behaviors and well-being, and macro-level social organization and change.

Assisted partner notification services to augment HIV testing and linkage to care in Kenya: study protocol for a cluster randomized trial.

BACKGROUND: HIV case-finding and linkage to care are critical for control of HIV transmission. In Kenya, >50% of seropositive individuals are unaware of their status. Assisted partner notification is a public health strategy that provides HIV testing to individuals with sexual exposure to HIV and are at risk of infection and disease. This parallel, cluster-randomized controlled trial will evaluate the effectiveness, cost-effectiveness, and feasibility of implementing HIV assisted partner notification services at HIV testing sites (clusters) in Kenya. METHODS/DESIGN: Eighteen sites were selected among health facilities in Kenya with well-established, high-volume HIV testing programs, to reflect diverse communities and health-care settings. Restricted randomization was used to balance site characteristics between study arms (n = 9 per arm). Sixty individuals testing HIV positive ('index partners') will be enrolled per site (inclusion criteria: ≥18 years, positive HIV test at a study site, willing to disclose sexual partners, and never enrolled for HIV care; exclusion criteria: pregnancy or high risk of intimate partner violence). Index partners provide names and contact information for all sexual partners in the past 3 years. At intervention sites, study staff immediately contact sexual partners to notify them of exposure, offer HIV testing, and link to care if HIV seropositive. At control sites, passive partner referral is performed according to national guidelines, and assisted partner notification is delayed by 6 weeks. Primary outcomes, assessed 6 weeks after index partner enrollment and analyzed at the cluster level, are the number of partners accepting HIV testing and number of HIV infections diagnosed and linked to care per index partner. Secondary outcomes are the incremental cost-effectiveness of partner notification and the costs of identifying >1 partner per index case. Participants are closely monitored for adverse outcomes, particularly intimate partner violence. The study is unblinded due to practical limitations. DISCUSSION: This rigorously designed trial will inform policy decisions regarding implementation of HIV partner notification services in Kenya, with possible application to other parts of sub-Saharan Africa. Examination of effectiveness and cost-effectiveness in diverse settings will enable targeted application and define best practices. TRIAL REGISTRATION: ClinicalTrials.gov NCT01616420 .

Local health department food safety and sanitation expenditures and reductions in enteric disease, 2000-2010.

OBJECTIVES: In collaboration with Public Health Practice-Based Research Networks, we investigated relationships between local health department (LHD) food safety and sanitation expenditures and reported enteric disease rates. METHODS: We combined annual infection rates for the common notifiable enteric diseases with uniquely detailed, LHD-level food safety and sanitation annual expenditure data obtained from Washington and New York state health departments. We used a multivariate panel time-series design to examine ecologic relationships between 2000-2010 local food safety and sanitation expenditures and enteric diseases. Our study population consisted of 72 LHDs (mostly serving county-level jurisdictions) in Washington and New York. RESULTS: While controlling for other factors, we found significant associations between higher LHD food and sanitation spending and a lower incidence of salmonellosis in Washington and a lower incidence of cryptosporidiosis in New York. CONCLUSIONS: Local public health expenditures on food and sanitation services are important because of their association with certain health indicators. Our study supports the need for program-specific LHD service-related data to measure the cost, performance, and outcomes of prevention efforts to inform practice and policymaking.

Classifying local health departments on the basis of the constellation of services they provide.

OBJECTIVES: We explored service variation among local health departments (LHDs) nationally to allow systematic characterization of LHDs by patterns in the constellation of services they deliver. METHODS: We conducted latent class analysis by using categorical variables derived from LHD service data collected in 2008 for the National Profile of Local Health Departments Survey and before service changes resulting from the national financial crisis. RESULTS: A 3-class solution produced the best fit for this data set of 2294 LHDs. The 3 configurations of LHD services depicted an interrelated set of narrow or limited service provision (limited), a comprehensive (core) set of key services provided, and a third class of core and expanded services (core plus), which often included rare services. The classes demonstrated high geographic variability and were weakly associated with expenditure quintile and urban or rural location. CONCLUSIONS: This empirically derived view of how LHDs organize their array of services is a unique approach to categorizing LHDs, providing an important tool for research and a gauge to monitor how changes in LHD service patterns occur.

Targeted health department expenditures benefit birth outcomes at the county level.

BACKGROUND: Public health leaders lack evidence for making decisions about the optimal allocation of resources across local health department (LHD) services, even as limited funding has forced cuts to public health services while local needs grow. A lack of data has also limited examination of the outcomes of targeted LHD investments in specific service areas. PURPOSE: This study used unique, detailed LHD expenditure data gathered from state health departments to examine the influence of maternal and child health (MCH) service investments by LHDs on health outcomes. METHODS: A multivariate panel time-series design was used in 2013 to estimate ecologic relationships between 2000-2010 LHD expenditures on MCH and county-level rates of low birth weight and infant mortality. The unit of analysis was 102 LHD jurisdictions in Washington and Florida. RESULTS: Results indicate that LHD expenditures on MCH services have a beneficial relationship with county-level low birth weight rates, particularly in counties with high concentrations of poverty. This relationship is stronger for more targeted expenditure categories, with expenditures in each of the three specific examined MCH service areas demonstrating the strongest effects. CONCLUSIONS: Findings indicate that specific LHD investments in MCH have an important effect on related health outcomes for populations in poverty and likely help reduce the costly burden of poor birth outcomes for families and communities. These findings underscore the importance of monitoring the impact of these evolving investments and ensuring that targeted, beneficial investments are not lost but expanded upon across care delivery systems.

Local health departments and specific maternal and child health expenditures: relationships between spending and need.

OBJECTIVE: As a part of the Public Health Activities and Service Tracking study and in collaboration with partners in 2 Public Health Practice-Based Research Network states, we examined relationships between local health department (LHD) maternal and child health (MCH) expenditures and local needs. DESIGN: We used a multivariate pooled time-series design to estimate ecologic associations between expenditures in 3 MCH-specific service areas and related measures of need from 2005 to 2010 while controlling for other factors. MEASURES: Retrospective expenditure data from LHDs and for 3 MCH services represented annual investments in (1) Special Supplemental Nutrition for Women, Infants, and Children (WIC), (2) family planning, and (3) a composite of Maternal, Infant, Child, and Adolescent (MICA) service. Expenditure data from all LHDs in Florida and Washington were then combined with "need" and control variables. STUDY POPULATION: Our sample consisted of the 102 LHDs in Florida and Washington and the county (or multicounty) jurisdictions they serve. RESULTS: Expenditures for WIC and for our composite of MICA services were strongly associated with need among LHDs in the sample states. For WIC, this association was positive, and for MICA services, this association was negative. Family planning expenditures were weakly associated, in a positive direction. CONCLUSIONS: Findings demonstrate wide variations across programs and LHDs in relation to need and may underscore differences in how programs are funded. Programs with financial disbursements based on guidelines that factor in local needs may be better able to provide service as local needs grow than programs with less needs-based funding allocations.

Local Health Department Provision of WIC Services Relative to Local "Need"- Examining 3 States and 5 Years.

Great variation exists in the nature of LHD service delivery and it varies, in part, relative to jurisdiction population size. Larger LHD jurisdictions may achieve an economy of scale in WIC service delivery that is not matched in smaller areas. Overall, we found that WIC service provision appears relatively consistent across study states and in the presence of increasing need, with greater responsiveness to need in urban areas. As demand for some preventive services increases LHDs in rural areas may need greater support than LHDs in large jurisdictions for meeting local demand. Unlike WIC, LHD-provided services that have less consistently maintained service-delivery guidelines may have a harder time responding to increasing need. The relative consistency of a federally-funded program such as WIC may serve as a good baseline for further study of less consistently delivered programs among LHDs. LHD service statistics can serve as useful data sources in measuring volume of service delivery relative to need.

Validation of the normalized difference vegetation index as a measure of neighborhood greenness.

PURPOSE: To assess the validity of a Geographic Information Systems (GIS) measure, the Normalized Difference Vegetation Index (NDVI), as a measure of neighborhood greenness for epidemiologic research. METHODS: Using remote-sensing spectral data, NDVI was calculated for a 100-m radial distance around 124 residences in greater Seattle. The criterion standard was rating of greenness for corresponding residential areas by 3 environmental psychologists. Pearson correlations and regression models were used to assess the association between the psychologists' ratings of greenness and NDVI. Analyses were also stratified by residential density to assess whether the correlations differed between low and high density. RESULTS: The mean NDVI among this sample of residences was 0.27 (standard deviation [SD], 0.11; range, -0.04 to 0.54), and the mean psychologist rating of greenness was 2.84 (SD, 0.98; range, 1-5). The correlation between NDVI and expert ratings of greenness was high (r = 0.69). The correlation was equivalently strong within each strata of residential density. CONCLUSIONS: NDVI is a useful measure of neighborhood greenness. In addition to showing a strong correlation with expert ratings, this measure has practical advantages, including availability of data and ease of application to various boundaries, which would aid in replication and comparability across studies.