Scott C. Brown

Is Dual-Chamber Programming Inferior to Single-Chamber Programming in an Implantable Cardioverter-Defibrillator? Results of the INTRINSIC RV (Inhibition of Unnecessary RV Pacing With AVSH in ICDs) Study

Background— The INTRINSIC RV (Inhibition of Unnecessary RV Pacing with AVSH in ICDs) study tested the hypothesis that dual-chamber rate-responsive (DDDR) with atrioventricular search hysteresis (AVSH) 60-130 programming is not inferior to single-chamber (VVI)–40 programming in an implantable cardioverter defibrillator with respect to all-cause mortality and heart failure hospitalizations using an equivalence margin of 5%. Methods and Results— At 108 centers, 1530 patients with an implantable cardioverter defibrillator indication received a VITALITY AVT (Guidant Corporation, St. Paul, Minn) implantable cardioverter defibrillator programmed consistently to DDDR AVSH 60-130 for the first week. Of those, 988 patients with <20% right ventricular pacing at 1 week were randomized to DDDR AVSH 60-130 or to VVI-40 programming. Among those randomized, 502 were assigned to DDDR AVSH and 486 to VVI. Groups were similar with regard to coronary disease (68%), gender (21% female), and New York Heart Association functional class >I (79%). A total of 32 patients (6.4%) in the DDDR AVSH arm and 46 patients (9.5%) in the VVI arm died or were hospitalized for heart failure during a mean follow-up of 10.4 months (relative risk=0.67, P=0.072 in favor of DDDR AVSH). DDDR AVSH was not inferior to VVI programming (P<0.001). All-cause mortality was not significantly different between the DDDR AVSH arm (3.6%) and the VVI arm (5.1%; P=0.23). The mean percent right ventricular pacing in the DDDR AVSH arm was 10% (median 4%) versus 3% (median 0%) in the VVI arm. Conclusions— In the INTRINSIC RV trial, among those randomized, DDDR AVSH was associated with similar outcomes as with VVI backup pacing.

The relationship of pain and depression to cognitive function in rheumatoid arthritis patients

&NA; The purpose of this study was to assess the hypothesis that pain and depression negatively impact the cognitive functioning of individuals with rheumatoid arthritis (RA). One hundred twenty‐one community‐dwelling RA patients (ages 34–84) completed a battery of cognitive tasks and multiple measures of pain and depression. Structural equation modeling techniques were used to assess the relative contributions of pain, depression, and age to cognitive performance. Individuals who performed poorly on cognitive tasks reported more pain and depression and were older than those individuals who performed well on cognitive tasks. Moreover, high levels of pain were associated with depression. Further analyses revealed that depression mediated the relationship between pain and cognition. That is, when depression was entered into the analyses, the previously significant effects of pain on cognition were no longer found. Interestingly, depression still mediated the pain–cognition relationship even after controlling for age. These findings suggest the importance of both pain and depression for understanding cognitive function in RA and may have important implications for treating this disease.

Heart Rate Predicts Outcomes in an Implantable Cardioverter-Defibrillator Population

Background— Elevated heart rate (HR) is associated with adverse cardiovascular events and total mortality in the general population and in individuals with heart disease. Our hypothesis was that mean HR predicts total mortality and heart failure hospitalization in patients undergoing implantable cardioverter-defibrillator (ICD) implantation. Methods and Results— The Inhibition of Unnecessary RV Pacing With AV Search Hysteresis in ICDs (INTRINSIC RV) trial included 1530 patients undergoing ICD implantation. After implantation of a dual-chamber ICD, patients were followed for a mean of 10.4 months. The mean HR for 1436 patients over the follow-up period was determined from device histograms. Patients were grouped into strata by mean HR, and the relationship between the primary end point and mean HR was analyzed with Mantel-Haenszel ordinal &khgr;2 tests. Higher intrinsic (unpaced) HR was associated with greater risk of achieving the primary end point of death or heart failure hospitalization (P<0.001). Of patients with a mean HR <75 bpm, 5.8% died or were hospitalized for heart failure, whereas 20.9% with a mean HR >90 bpm achieved the same end point, a 3.6-fold difference (P<0.0001). In a multivariate model with the use of Cox regression, HR was a significant predictor with a hazard ratio of 1.34 (P=0.0001; 95% confidence interval, 1.19 to 1.50), as were age, New York Heart Association functional class, and percent right ventricular pacing, but it was independent of gender and &bgr;-blocker dosing. When considered as continuous or discrete variables grouped by 5-bpm increments, HR remained a significant predictor. Conclusions— In this ICD population, the mean intrinsic HR was strongly associated with outcomes. Clinical Trial Registration— http://www.clinicaltrials.gov. Identifier: NCT00148967.

The Relationship between Social Support and Psychological Distress among Hispanic Elders in Miami, Florida.

This study compared 5 psychological models of the relationship between social support (SS) and behavioral health. These theoretical models, which have garnered some level of prior empirical support, were as follows: (a) main effects, (b) buffering effects, (c) social exchange, (d) equity, and (e) protective health outcomes of providing SS. A population-based sample of 273 community-dwelling Hispanic elders drawn from East Little Havana, Florida (ages 70-100 years old; 86% Cuban) completed self-report measures of SS, financial strain, and psychological distress (PD). Hierarchical multiple regression analyses were used to test the competing SS models. Results indicated that satisfaction with received SS was, as specified in the main-effects model, associated with lower PD, whereas received SS was unexpectedly associated with heightened PD. Reciprocal exchanges of SS (equity model) or exchanges where Hispanic elders provided more SS than they received (protective health outcomes of providing SS model) were also associated with lower PD. The feasibility of a 6th model in which the effects of SS are contingent upon the elders preexisting PD level is proposed. Limitations, implications, and directions for future research are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved).

The relationship between depressive symptoms and walking among Hispanic older adults: a longitudinal, cross-lagged panel analysis.

Objectives: This study examines the relationship between depressive symptoms and walking behavior across 30 months in a prospective study of 217 community-dwelling, Hispanic older adults in Miami, Florida (ages 70–100 years). Method: Analyses examine the direction of the relationship between depressive symptoms and physical activity (i.e., walking) over time, as well as test for a potential bi-directional or reciprocal relationship between these two variables. Results: Structural equation modeling (SEM) with a cross-lagged panel design revealed that walking was unrelated to subsequent depressive symptoms. However, depressive symptoms were related to subsequent walking behavior at every time-point, such that higher levels of depressive symptoms were predictive of less walking in the future. Older adults who had clinically-relevant depressive symptoms at the initial assessment had 1.34 times the risk of not walking 30 months later, compared to older adults without clinically-relevant depressive symptoms. Conclusion: Results support the need for primary care providers to evaluate and address depressive symptoms among older adults, as a means of reducing sedentary behavior and potentially improving health. Further research on the prevention and management of depressive symptoms and sedentary behavior is needed, given the morbidity related to both of these health risks, particularly for minority and low-socio-economic status (SES) older adults.

Neighborhood Greenness and Chronic Health Conditions in Medicare Beneficiaries

INTRODUCTION Prior studies suggest that exposure to the natural environment may impact health. The present study examines the association between objective measures of block-level greenness (vegetative presence) and chronic medical conditions, including cardiometabolic conditions, in a large population-based sample of Medicare beneficiaries in Miami-Dade County, Florida. METHODS The sample included 249,405 Medicare beneficiaries aged ≥65 years whose location (ZIP+4) within Miami-Dade County, Florida, did not change, from 2010 to 2011. Data were obtained in 2013 and multilevel analyses conducted in 2014 to examine relationships between greenness, measured by mean Normalized Difference Vegetation Index from satellite imagery at the Census block level, and chronic health conditions in 2011, adjusting for neighborhood median household income, individual age, gender, race, and ethnicity. RESULTS Higher greenness was significantly associated with better health, adjusting for covariates: An increase in mean block-level Normalized Difference Vegetation Index from 1 SD less to 1 SD more than the mean was associated with 49 fewer chronic conditions per 1,000 individuals, which is approximately similar to a reduction in age of the overall study population by 3 years. This same level of increase in mean Normalized Difference Vegetation Index was associated with a reduced risk of diabetes by 14%, hypertension by 13%, and hyperlipidemia by 10%. Planned post-hoc analyses revealed stronger and more consistently positive relationships between greenness and health in lower- than higher-income neighborhoods. CONCLUSIONS Greenness or vegetative presence may be effective in promoting health in older populations, particularly in poor neighborhoods, possibly due to increased time outdoors, physical activity, or stress mitigation.

Depressive Symptoms, Social Support, and Walking Among Hispanic Older Adults

Objectives: Depressive symptoms and physical inactivity are health risks among minority older adults. This study examined whether social support moderated the relationship of depressive symptoms to walking behavior among 217 community-dwelling, Hispanic older adults. Method: Cross-sectional analyses were used to test whether different forms of social support interacted with depressive symptoms to affect both likelihood and amount of walking. Results: Analyses showed a significant interaction between depressive symptoms and instrumental support related to the likelihood of walking and a marginally significant interaction between depressive symptoms and instrumental social support related to the amount of walking. Depressive symptoms were associated with a lower likelihood and lower amount of walking among participants receiving high levels of instrumental social support (e.g., help with chores) but not low instrumental support. Emotional and informational support did not moderate the depression to walking relationship. Conclusion: Receiving too much instrumental support was related to sedentary behavior among depressed older adults.

Host outdoor exposure variability affects the transmission and spread of Zika virus: Insights for epidemic control

Background Zika virus transmission dynamics in urban environments follow a complex spatiotemporal pattern that appears unpredictable and barely related to high mosquito density areas. In this context, human activity patterns likely have a major role in Zika transmission dynamics. This paper examines the effect of host variability in the amount of time spent outdoors on Zika epidemiology in an urban environment. Methodology/Principal findings First, we performed a survey on time spent outdoors by residents of Miami-Dade County, Florida. Second, we analyzed both the survey and previously published national data on outdoors time in the U.S. to provide estimates of the distribution of the time spent outdoors. Third, we performed a computational modeling evaluation of Zika transmission dynamics, based on the time spent outdoors by each person. Our analysis reveals a strong heterogeneity of the host population in terms of time spent outdoors–data are well captured by skewed gamma distributions. Our model-based evaluation shows that in a heterogeneous population, Zika would cause a lower number of infections than in a more homogenous host population (up to 4-fold differences), but, at the same time, the epidemic would spread much faster. We estimated that in highly heterogeneous host populations the timing of the implementation of vector control measures is the major factor for limiting the number of Zika infections. Conclusions/Significance Our findings highlight the need of considering host variability in exposure time for managing mosquito-borne infections and call for the revision of the triggers for vector control strategies, which should integrate mosquito density data and human outdoor activity patterns in specific areas.

Expanding Integrated Vector Management to promote healthy environments

Integrated Vector Management (IVM) strategies are intended to protect communities from pathogen transmission by arthropods. These strategies target multiple vectors and different ecological and socioeconomic settings, but the aggregate benefits of IVM are limited by the narrow focus of its approach; IVM strategies aim only to control arthropod vectors. We argue that IVM should encompass environmental modifications at early stages - for instance, infrastructural development and sanitation services - to regulate not only vectors but also nuisance biting arthropods. An additional focus on nuisance biting arthropods will improve public health and quality of life and minimize social-disparity issues fostered by pests. Optimally, IVM could incorporate environmental awareness and promotion of control methods proactively to reduce threats of serious pest situations.

Walking and Proximity to the Urban Growth Boundary and Central Business District

BACKGROUND Planners have relied on the urban development boundary (UDB)/urban growth boundary (UGB) and central business district (CBD) to encourage contiguous urban development and conserve infrastructure. However, no studies have specifically examined the relationship between proximity to the UDB/UGB and CBD and walking behavior. PURPOSE To examine the relationship between UDB and CBD distance and walking in a sample of recent Cuban immigrants, who report little choice in where they live after arrival to the U.S. METHODS Data were collected in 2008-2010 from 391 healthy, recent Cuban immigrants recruited and assessed within 90 days of arrival to the U.S. who resided throughout Miami-Dade County FL. Analyses in 2012-2013 examined the relationship between UDB and CBD distances for each participants residential address and purposive walking, controlling for key sociodemographics. Follow-up analyses examined whether Walk Score(®), a built-environment walkability metric based on distance to amenities such as stores and parks, mediated the relationship between purposive walking and each of UDB and CBD distance. RESULTS Each one-mile increase in distance from the UDB corresponded to an 11% increase in the number of minutes of purposive walking, whereas each one-mile increase from the CBD corresponded to a 5% decrease in the amount of purposive walking. Moreover, Walk Score mediated the relationship between walking and each of UDB and CBD distance. CONCLUSIONS Given the lack of walking and walkable destinations observed in proximity to the UDB/UGB boundary, a sprawl repair approach could be implemented, which strategically introduces mixed-use zoning to encourage walking throughout the boundarys zone.