Alyssa Platt

Association of vitamin D deficiency and age-related macular degeneration in medicare beneficiaries

Several studies have found an association between vitamin D deficiency and age-related macular degeneration (AMD).1-4 Vitamin D has been shown to have immunomodulatory and antiangiogenic properties, suggesting a biologically plausible role in the pathogenesis of AMD.5 This study examines the possible association of vitamin D deficiency and subsequent incidence of first diagnosis of nonneovascular and neovascular AMD in a cohort of Medicare beneficiaries. To our knowledge, this is the first study to evaluate incidence rather than prevalence of AMD in a large sample of vitamin D–deficient patients.

Spatial autocorrelation in uptake of antenatal care and relationship to individual, household and village-level factors: results from a community-based survey of pregnant women in six districts in western Kenya

BackgroundThe majority of maternal deaths, stillbirths, and neonatal deaths are concentrated in a few countries, many of which have weak health systems, poor access to health services, and low coverage of key health interventions. Early and consistent antenatal care (ANC) attendance could significantly reduce maternal and neonatal morbidity and mortality. Despite this, most Kenyan mothers initiate ANC care late in pregnancy and attend fewer than the recommended visits.MethodsWe used survey data from 6,200 pregnant women across six districts in western Kenya to understand demand-side factors related to use of ANC. Bayesian multi-level models were developed to explore the relative importance of individual, household and village-level factors in relation to ANC use.ResultsThere is significant spatial autocorrelation of ANC attendance in three of the six districts and considerable heterogeneity in factors related to ANC use between districts. Working outside the home limited ANC attendance. Maternal age, the number of small children in the household, and ownership of livestock were important in some districts, but not all. Village proportions of pregnancy in women of child-bearing age was significantly correlated to ANC use in three of the six districts. Geographic distance to health facilities and the type of nearest facility was not correlated with ANC use. After incorporating individual, household and village-level covariates, no residual spatial autocorrelation remained in the outcome.ConclusionsANC attendance was consistently low across all the districts, but factors related to poor attendance varied. This heterogeneity is expected for an outcome that is highly influenced by socio-cultural values and local context. Interventions to improve use of ANC must be tailored to local context and should include explicit approaches to reach women who work outside the home.

Changes in Functional Status Among Persons Over Age Sixty-Five Undergoing Total Knee Arthroplasty

Background:This study assessed changes in physical functional status following receipt of total knee arthroplasty (TKA) for patients diagnosed with osteoarthritis (OA) of the knee in a national sample of persons aged 65+ in the United States relative to a sample of similar OA patients who did not receive TKA. Methods:Data from the Health Retirement Survey (HRS) and linked Medicare claims from 1994 to 2006 were used to identify persons with diagnoses of OA of the lower leg who received a TKA (n = 516) and those who did not receive TKA (n = 1756). Predicted probabilities of receiving total knee arthroplasty from logit analysis were used for matching TKA and comparison groups on demographic, socioeconomic, and baseline functional status factors. Functional status measures were: mobility, gross motor function, large muscle, and limitations in activities of daily living (ADL). Average treatment effects of the treated (ATT), which compares changes in functional status between those who received TKA with similar individuals who did not receive TKA, were computed using propensity score matching. Results:Mobility (average treatment effect of the treated (ATT = 0.315; 95% CI: 0.118–0.512), gross motor function (ATT = 0.314; 95% CI: 0.156–0.472), and ADL limitations (ATT = 0.174; 95% CI: 0.055–0.293), improved among persons receiving TKA relative to the comparison group. Relative to the mean values of the physical function at baseline, mobility, gross motor function, and ADL limitations persons receiving TKA had better functional outcomes than the comparison group by 17.5, 39.3, and 46.9 percent, respectively. Conclusions:TKA is effective in improving functional status in elderly persons.

What Is Threatening the Effectiveness of Insecticide-Treated Bednets? A Case-Control Study of Environmental, Behavioral, and Physical Factors Associated with Prevention Failure

Background Insecticide-treated nets are the cornerstone of global malaria control and have been shown to reduce malaria morbidity by 50–60%. However, some areas are experiencing a resurgence in malaria following successful control. We describe an efficacy decay framework to understand why high malaria burden persists even under high ITN coverage in a community in western Kenya. Methods We enrolled 442 children hospitalized with malaria and paired them with age, time, village and gender-matched controls. We completed comprehensive household and neighborhood assessments including entomological surveillance. The indicators are grouped into five domains in an efficacy decay framework: ITN ownership, compliance, physical integrity, vector susceptibility and facilitating factors. After variable selection, case-control data were analyzed using conditional logistic regression models and mosquito data were analyzed using negative binomial regression. Predictive margins were calculated from logistic regression models. Results Measures of ITN coverage and physical integrity were not correlated with hospitalized malaria in our study. However, consistent ITN use (Adjusted Odds Ratio (AOR) = 0.23, 95%CI: 0.12–0.43), presence of nearby larval sites (AOR = 1.137, 95%CI: 1.02–1.27), and specific types of crops (AOR (grains) = 0.446, 95%CI: 0.24–0.82) were significantly correlated with malaria amongst children who owned an ITN. The odds of hospitalization for febrile malaria nearly tripled when one other household member had symptomatic malaria infection (AOR–2.76, 95%CI:1.83–4.18). Overall, perfect household adherence could reduce the probability of hospitalization for malaria to less than 30% (95%CI:0.12–0.46) and adjusting environmental factors such as elimination of larval sites and growing grains nearby could reduce the probability of hospitalization for malaria to less than 20% (95%CI:0.04–0.31). Conclusion Availability of ITNs is not the bottleneck for malaria prevention in this community. Behavior change interventions to improve compliance and environmental management of mosquito breeding habitats may greatly enhance ITN efficacy. A better understanding of the relationship between agriculture and mosquito survival and feeding success is needed.

Innovative public–private partnership to target subsidised antimalarials: a study protocol for a cluster randomised controlled trial to evaluate a community intervention in Western Kenya

Introduction There are concerns of inappropriate use of subsidised antimalarials due to the large number of fevers treated in the informal sector with minimal access to diagnostic testing. Targeting antimalarial subsidies to confirmed malaria cases can lead to appropriate, effective therapy. There is evidence that community health volunteers (CHVs) can be trained to safely and correctly use rapid diagnostic tests (RDTs). This study seeks to evaluate the public health impact of targeted antimalarial subsidies delivered through a partnership between CHVs and the private retail sector. Methods and analysis We are conducting a stratified cluster-randomised controlled trial in Western Kenya where 32 community units were randomly assigned to the intervention or control (usual care) arm. In the intervention arm, CHVs offer free RDT testing to febrile individuals and, conditional on a positive test result, a voucher to purchase a WHO-qualified artemisinin combination therapy (ACT) at a reduced fixed price in the retail sector. Study outcomes in individuals with a febrile illness in the previous 4 weeks will be ascertained through population-based cross-sectional household surveys at four time points: baseline, 6, 12 and 18 months postbaseline. The primary outcome is the proportion of fevers that receives a malaria test from any source (CHV or health facility). The main secondary outcome is the proportion of ACTs used by people with a malaria-positive test. Other secondary outcomes include: the proportion of ACTs used by people without a test and adherence to test results. Ethics and dissemination The protocol has been approved by the National Institutes of Health, the Moi University School of Medicine Institutional Research and Ethics Committee and the Duke University Medical Center Institutional Review Board. Findings will be reported on clinicalstrials.gov, in peer-reviewed publications and through stakeholder meetings including those with the Kenyan Ministry of Health. Trial registration number Pre-results, NCT02461628.

Deterring domestic violence: Do criminal sanctions reduce repeat offenses?

This study presents an empirical analysis of domestic violence case resolution in North Carolina for the years 2004 to 2010. The key hypothesis is that penalties at the level set for domestic violence crimes reduce recidivism (re-arrest on domestic violence charges or conviction in 2 years following an index arrest). We use state court data for all domestic violence-related arrests. Decisions to commit an act of domestic violence are based on a Bayesian process of updating subjective beliefs. Individuals have prior beliefs about penalties for domestic violence based on actual practice in their areas. An individual’s experience with an index arrest leads to belief updating. To address endogeneity of case outcomes, we use an instrumental variables strategy based on decisions of prosecutors and judges assigned to each index arrest in our sample. Contrary to our hypothesis, we find that penalities, at least as set at the current levels, do not deter future arrests and convictions.

Assessing the independent and combined effects of subsidies for antimalarials and rapid diagnostic testing on fever management decisions in the retail sector: results from a factorial randomised trial in western Kenya

Objectives There is an urgent need to understand how to improve targeting of artemisinin combination therapy (ACT) to patients with confirmed malaria infection, including subsidised ACTs sold over-the-counter. We hypothesised that offering an antimalarial subsidy conditional on a positive malaria rapid diagnostic test (RDT) would increase uptake of testing and improve rational use of ACTs. Methods We designed a 2×2 factorial randomised experiment evaluating 2 levels of subsidy for RDTs and ACTs. Between July 2014 and June 2015, 444 individuals with a malaria-like illness who had not sought treatment were recruited from their homes. We used scratch cards to allocate participants into 4 groups in a ratio of 1:1:1:1. Participants were eligible for an unsubsidised or fully subsidised RDT and 1 of 2 levels of ACT subsidy (current retail price or an additional subsidy conditional on a positive RDT). Treatment decisions were documented 1 week later. Our primary outcome was uptake of malaria testing. Secondary outcomes evaluated ACT consumption among those with a negative test, a positive test or no test. Results Offering a free RDT increased the probability of testing by 18.6 percentage points (adjusted probability difference (APD), 95% CI 5.9 to 31.3). An offer of a conditional ACT subsidy did not have an additional effect on the probability of malaria testing when the RDT was free (APD=2.7; 95% CI −8.6 to 14.1). However, receiving the conditional ACT subsidy increased the probability of taking an ACT following a positive RDT by 19.5 percentage points (APD, 95% CI 2.2 to 36.8). Overall, the proportion who took ACT following a negative test was lower than those who took ACT without being tested, indicated improved targeting among those who were tested. Conclusions Both subsidies improved appropriate fever management, demonstrating the impact of these costs on decision making. However, the conditional ACT subsidy did not increase testing. We conclude that each of the subsidies primarily impacts the most immediate decision. Trial registration number NCT02199977.

A mobile health technology platform for quality assurance and quality improvement of malaria diagnosis by community health workers

Background Community health workers (CHWs) play an important role in improving access to services in areas with limited health infrastructure or workforce. Supervision of CHWs by qualified health professionals is the main link between this lay workforce and the formal health system. The quality of services provided by lay health workers is dependent on adequate supportive supervision. It is however one of the weakest links in CHW programs due to logistical and resource constraints, especially in large scale programs. Interventions such as point of care testing using malaria rapid diagnostic tests (RDTs) require real time monitoring to ensure diagnostic accuracy. In this study, we evaluated the utility of a mobile health technology platform to remotely monitor malaria RDT (mRDT) testing by CHWs for quality improvement. Methods As part of a large implementation trial involving mRDT testing by CHWs, we introduced the Fionet system composed of a mobile device (Deki Reader, DR) to assist in processing and automated interpretation of mRDTs, which connects to a cloud-based database which captures reports from the field in real time, displaying results in a custom dashboard of key performance indicators. A random sample of 100 CHWs were trained and provided with the Deki Readers and instructed to use it on 10 successive patients. The CHWs interpretation was compared with the Deki Reader’s automatic interpretation, with the errors in processing and interpreting the RDTs recorded. After the CHW entered their interpretation on the DR, the DR provided immediate, automated feedback and interpretation based on its reading of the same cassette. The study team monitored the CHW performance remotely and provided additional support. Results A total of 1251 primary and 113 repeat tests were performed by the 97 CHWs who used the DR. 91.6% of the tests had agreement between the DR and the CHWs. There were 61 (4.9%) processing and 52 (4.2%) interpretation errors among the primary tests. There was a tendency towards lower odds of errors with increasing number and frequency of tests, though not statistically significant. Of the 62 tests that were repeated due to errors, 79% achieved concordance between the CHW and the DR. Satisfaction with the use of the DR by the CHWs was high. Conclusions Use of innovative mHealth strategies for monitoring and quality control can ensure quality within a large scale implementation of community level testing by lay health workers.

Deterring Rearrests for Drinking and Driving

This study assesses why some individuals are re-arrested for driving while intoxicated (DWI). Using longitudinal data from North Carolina containing information on arrests and arrest outcomes, we test hypotheses that individuals prosecuted and convicted of DWI are less likely to be re-arrested for DWI. We allow for possible endogeneity of prosecution and conviction outcomes by using instrumental variables for the prosecutors prosecution rate and the judges conviction rate. With a three-year follow-up, the probability of DWI re-arrest was reduced by 6.6 percent if the person was prosecuted for DWI and, for those prosecuted, by 24.5 percent if convicted on this charge. Prosecution and conviction for DWI deters re-arrest for DWI.

Dynamic malaria hotspots in an open cohort in western Kenya

Malaria hotspots, defined as areas where transmission intensity exceeds the average level, become more pronounced as transmission declines. Targeting hotspots may accelerate reductions in transmission and could be pivotal for malaria elimination. Determinants of hotspot location, particularly of their movement, are poorly understood. We used spatial statistical methods to identify foci of incidence of self-reported malaria in a large census population of 64,000 people, in 8,290 compounds over a 2.5-year study period. Regression models examine stability of hotspots and identify static and dynamic correlates with their location. Hotspot location changed over short time-periods, rarely recurring in the same area. Hotspots identified in spring versus fall season differed in their stability. Households located in a hotspot in the fall were more likely to be located in a hotspot the following fall (RR = 1.77, 95% CI: 1.66–1.89), but the opposite was true for compounds in spring hotspots (RR = 0.15, 95% CI: 0.08–0.28). Location within a hotspot was related to environmental and static household characteristics such as distance to roads or rivers. Human migration into a household was correlated with risk of hotspot membership, but the direction of the association differed based on the origin of the migration event.