Relative efficiency of unequal versus equal cluster sizes in cluster randomized trials using generalized estimating equation models

There is growing interest in conducting cluster randomized trials (CRTs). For simplicity in sample size calculation, the cluster sizes are assumed to be identical across all clusters. However, equal cluster sizes are not guaranteed in practice. Therefore, the relative efficiency (RE) of unequal versus equal cluster sizes has been investigated when testing the treatment effect. One of the most important approaches to analyze a set of correlated data is the generalized estimating equation (GEE) proposed by Liang and Zeger, in which the “working correlation structure” is introduced and the association pattern depends on a vector of association parameters denoted by ρ. In this paper, we utilize GEE models to test the treatment effect in a two‐group comparison for continuous, binary, or count data in CRTs. The variances of the estimator of the treatment effect are derived for the different types of outcome. RE is defined as the ratio of variance of the estimator of the treatment effect for equal to unequal cluster sizes. We discuss a commonly used structure in CRTs—exchangeable, and derive the simpler formula of RE with continuous, binary, and count outcomes. Finally, REs are investigated for several scenarios of cluster size distributions through simulation studies. We propose an adjusted sample size due to efficiency loss. Additionally, we also propose an optimal sample size estimation based on the GEE models under a fixed budget for known and unknown association parameter (ρ) in the working correlation structure within the cluster.     

Weaponizing Principles: Clinical Ethics Consultations & the Plight of the Morally Vulnerable

Internationally, there is an on‐going dialogue about how to professionalize ethics consultation services (ECSs). Despite these efforts, one aspect of ECS‐competence that has received scant attention is the liability of failing to adequately capture all of the relevant moral considerations in an ethics conflict. This failure carries a high price for the least powerful stakeholders in the dispute. When an ECS does not possess a sophisticated dexterity at translating what stakeholders say in a conflict into ethical concepts or principles, it runs the risk of naming one side's claims as morally legitimate and decrying the other's as merely self‐serving. The result of this failure is that one side in a dispute is granted significantly more moral weight and authority than the other. The remedy to this problem is that ECSs learn how to expand the diagnostic moral lens they employ in clinical ethics conflicts.     

Genomic characterization of metastatic patterns from prospective clinical sequencing of 25,000 patients

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Normal serum biochemical and hematological parameters in Macaca fascicularis.

The effects of age, sex, pregnancy, were analyzed and data from fasted and fed animals were compared in a population of cynomolgus macaques. No significant sex effects were observed for biochemical values and no changes were found in male hematological parameters in relation to age. Most values of females during pregnancy were within normal ranges. Comparison between fed and fasted animals showed that several biochemical parameters (e.g., ALT, glucose, CPK, LDH) and several hematological parameters (e.g., monocytes, eosinophils, basophils, hemoglobin, MCV, MCHC, and MCH) were affected by food intake.     

Stem cell research in Asia: A critical view

Stem cell research stands as a high‐priority field in many countries across the Asia‐Pacific region, and the past decade has seen remarkable investment into facilities and programs intended to increase competitiveness in the drive to find clinical applications. In the years roughly framed by Korean cloner Woo‐Suk Hwang's meteoric ascent and fall, speculation was rampant that Asia was poised to overtake the West in this field of science. But that potential remains unfulfilled. In this article, I will look at some of the deficits in infrastructure and governance that underlie the East–West stem cell gap, and suggest a number of measures that might be taken to remedy them. J. Cell. Biochem. 107: 853–856, 2009. © 2009 Wiley‐Liss, Inc.     

Identification of Tumor Antigens in the HLA Peptidome of Patient-derived Xenograft Tumors in Mouse

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Highlights

• •Sufficient tumor tissues are often unavailable large HLA peptidome discovery.
• •Using patient derived xenograft (PDX) tumors can overcome this limitation.
• •The large PDX HLA peptidomes expand significantly those of the original biopsies.
• •The HLA peptidomes of the PDX tumors included many tumor antigens.