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Background: Sample size calculation is a key point in the design of a randomized controlled trial. With time-to-event outcomes, it's often based on the logrank test. We provide a sample size calculation method for a composite endpoint (CE) based on the geometric average hazard ratio (gAHR) in case the proportional hazards assumption can be assumed to hold for the components, but not for the CE.Methods: The required number of events, sample size and power formulae are based on the non-centrality parameter of the logrank test under the alternative hypothesis which is a function of the gAHR. We use the web platform, CompARE, for the sample size computations. A simulation study evaluates the empirical power of the logrank test for the CE based on the sample size in terms of the gAHR. We consider different values of the component hazard ratios, the probabilities of observing the events in the control group and the degrees of association between the components. We illustrate the sample size computations using two published randomized controlled trials. Their primary CEs are, respectively, progression-free survival (time to progression of disease or death) and the composite of bacteriologically confirmed treatment failure or Staphylococcus aureus related death by 12 weeks.Results: For a target power of 0.80, the simulation study provided mean (± SE) empirical powers equal to 0.799 (±0.004) and 0.798 (±0.004) in the exponential and non-exponential settings, respectively. The power was attained in more than 95% of the simulated scenarios and was always above 0.78, regardless of compliance with the proportional-hazard assumption.Conclusions: The geometric average hazard ratio as an effect measure for a composite endpoint has a meaningful interpretation in the case of non-proportional hazards. Furthermore it is the natural effect measure when using the logrank test to compare the hazard rates of two groups and should be used instead of the standard hazard ratio. [ABSTRACT FROM AUTHOR]

Background: High food insecurity has been demonstrated in rural American Indian households, but little is known about American Indian families in urban settings or the association of food insecurity with diet for these families. The purpose of this study was to examine the prevalence of food insecurity in American Indian households by urban-rural status, correlates of food insecurity in these households, and the relationship between food insecurity and diet in these households.Methods: Dyads consisting of an adult caregiver and a child (2-5 years old) from the same household in five urban and rural American Indian communities were included. Demographic information was collected, and food insecurity was assessed using two validated items from the USDA Household Food Security Survey. Factors associated with food insecurity were examined using logistic regression. Child and adult diets were assessed using food screeners. Coping strategies were assessed through focus group discussions. These cross-sectional baseline data were collected from 2/2013 through 4/2015 for the Healthy Children, Strong Families 2 randomized controlled trial of a healthy lifestyles intervention for American Indian families.Results: A high prevalence of food insecurity was determined (61%) and was associated with American Indian ethnicity, lower educational level, single adult households, WIC participation, and urban settings (p = 0.05). Food insecure adults had significantly lower intake of vegetables (p < 0.05) and higher intakes of fruit juice (<0.001), other sugar-sweetened beverages (p < 0.05), and fried potatoes (p < 0.001) than food secure adults. Food insecure children had significantly higher intakes of fried potatoes (p < 0.05), soda (p = 0.01), and sports drinks (p < 0.05). Focus group participants indicated different strategies were used by urban and rural households to address food insecurity.Conclusions: The prevalence of food insecurity in American Indian households in our sample is extremely high, and geographic designation may be an important contributing factor. Moreover, food insecurity had a significant negative influence on dietary intake for families. Understanding strategies employed by households may help inform future interventions to address food insecurity.Trial Registration: ( NCT01776255 ). Registered: January 16, 2013. Date of enrollment: February 6, 2013. [ABSTRACT FROM AUTHOR]

Background: Components of the microenvironment such as bone marrow stromal cells (BMSCs) are well known to support multiple myeloma (MM) disease progression and resistance to chemotherapy including the proteasome inhibitor bortezomib. However, functional distinctions between BMSCs in MM patients and those in disease-free marrow are not completely understood. We and other investigators have recently reported that NF-κB activity in primary MM cells is largely resistant to the proteasome inhibitor bortezomib, and that further enhancement of NF- κB by BMSCs is similarly resistant to bortezomib and may mediate resistance to this therapy. The mediating factor (s) of this bortezomib-resistant NF-κB activity is induced by BMSCs is not currently understood. Results: Here we report that BMSCs specifically derived from MM patients are capable of further activating bortezomib-resistant NF-κB activity in MM cells. This induced activity is mediated by soluble proteinaceous factors secreted by MM BMSCs. Among the multiple factors evaluated, interleukin-8 was secreted by BMSCs from MM patients at significantly higher levels compared to those from non-MM sources, and we found that IL-8 contributes to BMSC-induced NF-κB activity. Conclusions: BMSCs from MM patients uniquely enhance constitutive NF-κB activity in MM cells via a proteinaceous secreted factor in part in conjunction with IL-8. Since NF-κB is known to potentiate MM cell survival and confer resistance to drugs including bortezomib, further identification of the NF-κB activating factors produced specifically by MM-derived BMSCs may provide a novel biomarker and/or drug target for the treatment of this commonly fatal disease. [ABSTRACT FROM AUTHOR]