Blood conservation with membrane oxygenators and dipyridamole

Cardiopulmonary bypass induces platelet activation and dysfunction, which result in platelet deposition and depletion. Reduced platelet numbers and abnormal platelet function may contribute to postoperative bleeding. A membrane oxygenator may preserve platelets and reduce bleeding more than a bubble oxygenator, and the antiplatelet agent dipyridamole may protect platelets intraoperatively and reduce bleeding postoperatively. A prospective randomized trial was performed in 44 patients undergoing elective coronary artery bypass grafting to assess the effects of the membrane oxygenator and dipyridamole on platelet counts, platelet activation products, and postoperative bleeding. Patients who were randomized to receive a bubble oxygenator and no dipyridamole had the lowest postoperative platelet counts, the greatest blood loss, and the most blood products transfused. Platelet counts were highest and blood loss was least in patients randomized to receive a membrane oxygenator and dipyridamole (p less than .05). A bubble oxygenator with dipyridamole and a membrane oxygenator without dipyridamole resulted in intermediate postoperative platelet counts and blood loss. Arterial thromboxane B2 and platelet factor 4 concentrations were elevated on cardiopulmonary bypass in all groups. Both the membrane oxygenator and dipyridamole were independently effective (by multivariate analysis) in preserving platelets. Optimal blood conservation was achieved with a membrane oxygenator and dipyridamole.     

Exposure,hazard, and survival analysis of diffusion on social networks

Sociologists, economists, epidemiologists, and others recognize the importance of social networks in the diffusion of ideas and behaviors through human societies. To measure the flow of information on real‐world networks, researchers often conduct comprehensive sociometric mapping of social links between individuals and then follow the spread of an “innovation” from reports of adoption or change in behavior over time. The innovation is introduced to a small number of individuals who may also be encouraged to spread it to their network contacts. In conjunction with the known social network, the pattern of adoptions gives researchers insight into the spread of the innovation in the population and factors associated with successful diffusion. Researchers have used widely varying statistical tools to estimate these quantities, and there is disagreement about how to analyze diffusion on fully observed networks. Here, we describe a framework for measuring features of diffusion processes on social networks using the epidemiological concepts of exposure and competing risks. Given a realization of a diffusion process on a fully observed network, we show that classical survival regression models can be adapted to estimate the rate of diffusion, and actor/edge attributes associated with successful transmission or adoption, while accounting for the topology of the social network. We illustrate these tools by applying them to a randomized network intervention trial conducted in Honduras to estimate the rate of adoption of 2 health‐related interventions—multivitamins and chlorine bleach for water purification—and determine factors associated with successful social transmission.     

Capacity to Participation in Cerebral Palsy: Evidence of an Indirect Path Via Performance

Objective

To examine the hypothesis that the influence of physical activity capacity on participation is mediated through activity performance.

Design

Secondary analysis of a prospective cross-sectional study sample.

Setting

Regional pediatric specialty care hospital.

Participants

Children (N=128; 59% boys; age range, 2–9y) with cerebral palsy with Gross Motor Function Classification System levels I to III; 49% had hemiplegia, and 72% had spasticity.

Interventions

Not applicable.

Main Outcome Measures

Activity capacity was measured with the Gross Motor Function Measure-66, performance was measured with the Activities Scale for Kids, and participation was measured with the Assessment of Life Habits. Children's Assessment of Participation and Enjoyment and the Assessment of Preschool Children's Participation assessed diversity participation. Regression equations and Sobel z test were used to examine the mediated effect via performance.

Results

Physical activity performance mediates 74.9% (β=.83, P<.001) of the effect of activity capacity on total participation levels and 52.8% (β=.47, P=.001) of the effect of capacity on diversity participation.

Conclusions

The relation between what an ambulatory child with cerebral palsy is able to perform in a clinical setting and their participation in life is significantly mediated by what they actually do motorically in day-to-day life. Results suggest that interventions focusing on improving what they actually do every day, regardless of their capacity to perform (what they can do when tested), may positively influence participation.     

Effects of Proximate Foreclosed Properties on Individuals’ Weight Gain in Massachusetts, 1987–2008

Objectives. We assessed the extent to which living near foreclosed properties is associated with individuals’ subsequent weight gain.Methods. We linked health and address information on 2068 Framingham Offspring Cohort members (7830 assessments) across 5 waves (1987–2008) to records of all Massachusetts foreclosures during that period. We used counts of lender-owned foreclosed properties within 100 meters of participants’ homes to predict body mass index (BMI; defined as weight in kilograms divided by the square of height in meters) and the odds of being overweight (BMI ≥ 25), adjusted for individual and area-level covariates.Results. Mean BMI increased from 26.6 in 1987–1991 to 28.5 in 2005–2008; overweight prevalence increased from 59.0% to 71.3%. Foreclosures were within 100 meters of 159 (7.8%) participants’ homes on 187 occasions (1.8%), in 42 municipalities (21%). For each additional foreclosure, BMI increased by 0.20 units (95% confidence interval [CI] = 0.03, 0.36), and the odds ratio for being overweight associated with proximity to a foreclosure was 1.77 (95% CI = 1.02, 3.05).Conclusions. We found a robust association between living near foreclosures and BMI, suggesting that neighbors’ foreclosures may spur weight gain.More than 6 million mortgages were involved in foreclosure between 2007 and 2010,1 and more than 1.8 million US homes (1.5% of all housing units) were subject to a foreclosure filing in 2011 alone.2 Researchers have expressed concerns about the impact of the housing crisis on the public’s health,3–5 identifying housing distress and many of its sequelae as health risk factors.6–10 However, robust empirical evidence regarding the association between foreclosure and health remains sparse (Table A, available as a supplement to this article at http://www.ajph.org).11–18 Current studies, though useful, are limited by cross-sectional data,11,12,18 ecologic study designs,16 retrospective reporting,15,17 and self-reported measures.11–15,18 Although it is crucial that living close to foreclosed properties (i.e., homes that have been repossessed by lenders for nonpayment of mortgages) could affect the health of individuals not personally experiencing foreclosure, only 2 existing papers conceptualize foreclosure as a community-level health risk factor.11,16Because they are typically vacant, bank-owned foreclosures can be unsightly or dangerous if poorly maintained or unsecured. They also compete with nearby properties for sale. Both these disamenity and supply-side impacts are thought to lower nearby home values,19–22 potentially provoking fears of reduced home equity among neighbors. Foreclosures have also been shown to encourage crime,23 to disrupt neighborhood social networks and strain social support systems,4 and to degrade the quality of the built environment as a form of blight.Many of these economic, social, and physical impacts are, in turn, documented health risk factors, and in some studies, associated with higher BMI.24–29 With the Framingham Offspring Cohort data between years 1987 and 2008, and linking these to geocoded data on foreclosed properties, we tested the hypothesis that living near foreclosures is a risk factor for higher objectively measured body mass index (BMI; defined as weight in kilograms divided by the square of height in meters) and odds of being overweight.