Joint modeling of longitudinal and survival data with the Cox model and two-phase sampling

A common objective of cohort studies and clinical trials is to assess time-varying longitudinal continuous biomarkers as correlates of the instantaneous hazard of a study endpoint. We consider the setting where the biomarkers are measured in a designed sub-sample (i.e., case-cohort or two-phase sampling design), as is normative for prevention trials. We address this problem via joint models, with underlying biomarker trajectories characterized by a random effects model and their relationship with instantaneous risk characterized by a Cox model. For estimation and inference we extend the conditional score method of Tsiatis and Davidian (Biometrika 88(2):447–458, 2001) to accommodate the two-phase biomarker sampling design using augmented inverse probability weighting with nonparametric kernel regression. We present theoretical properties of the proposed estimators and finite-sample properties derived through simulations, and illustrate the methods with application to the AIDS Clinical Trials Group 175 antiretroviral therapy trial. We discuss how the methods are useful for evaluating a Prentice surrogate endpoint, mediation, and for generating hypotheses about biological mechanisms of treatment efficacy.     

A simulation study of methods for selecting subgroup‐specific doses in phase 1 trials

Patient heterogeneity may complicate dose‐finding in phase 1 clinical trials if the dose‐toxicity curves differ between subgroups. Conducting separate trials within subgroups may lead to infeasibly small sample sizes in subgroups having low prevalence. Alternatively,it is not obvious how to conduct a single trial while accounting for heterogeneity. To address this problem,we consider a generalization of the continual reassessment method on the basis of a hierarchical Bayesian dose‐toxicity model that borrows strength between subgroups under the assumption that the subgroups are exchangeable. We evaluate a design using this model that includes subgroup‐specific dose selection and safety rules. A simulation study is presented that includes comparison of this method to 3 alternative approaches,on the basis of nonhierarchical models,that make different types of assumptions about within‐subgroup dose‐toxicity curves. The simulations show that the hierarchical model‐based method is recommended in settings where the dose‐toxicity curves are exchangeable between subgroups. We present practical guidelines for application and provide computer programs for trial simulation and conduct.     

Agreement and discrepancy between children,parents, and social workers on school‐based effort avoidance in child welfare services

A multiperspective approach is beneficial for obtaining reliable and multifaceted pictures of child behaviour problems. The goal of the present study is to examine interrater agreement on school‐based effort avoidance between children receiving child welfare services, parents, and social workers. Given previous findings, interrater agreement is expected to be low. Self‐reported data on school‐based effort avoidance were gathered for children and adolescents in child welfare services. Additionally, social workers (using the Teacher‐Report Checklist for social and learning behaviour) and parents (using the parallel version of the self‐rating questionnaire on school‐based effort avoidance) were asked to complete an external assessment tool to compare children's perspectives with the ratings of significant adults. The results confirmed significant discrepancies between parents' and children's ratings on effort avoidance tendencies. Furthermore, there were only small to moderate correlations between children's self‐ratings and the adults' assessments; however, the consensus between adults was higher than the interrater agreement between children and social workers. Discrepancies in ratings from multiple informants underline the importance of integrating multiple perspectives, especially children's perspectives, in the diagnostic process in order to plan and adapt appropriate care and treatment.     

Misbeliefs About Gambling in a Convenience Sample from the General Population

We examined knowledge about the role of randomness in gambling and the principle of independence of events, in a community sample. We also investigated whether this knowledge varies according to gender and age. A convenience sample of 1257 residents in French-speaking Switzerland, aged 18–88 years (28.5% of women) completed a short online questionnaire. This assessed the perceived role of human skills in four different games as well as beliefs relating to the principle of independence of events. The results show that 19.5% of the respondents perceived Roulette as a game for which the outcome is determined by skill. They also showed that 15.1% of the respondents did not hold beliefs about the independence of events principle. Gender and age differences were also observed: Men were proportionally more likely to hold erroneous beliefs about gambling skills and the independence of events, compared to women. The 18–25 year-old age group attributed Roulette outcomes to the gambler’s skill more frequently than the older categories. The implications of these findings for prevention and social support are discussed.     

Who is leading the campaign charts? Comparing individual popularity on old and new media

Attention in the mass media is seen as crucial for electoral success. However, most ordinary candidates hardly get any attention in the news. With social media outlets becoming ever more popular, the question is whether the overall asymmetry in attention for candidates still holds today. Do candidates who dominate the traditional media during the campaign also dominate the social media? Or can candidates make up for a lack of mass media coverage by attracting attention on these new media platforms? This paper aims to answer these questions by pairing Twitter activity and Twitter popularity with newspaper attention for a large number of individual candidates in the 2014 Belgian election campaign. We expand the normalization versus equalization debate by not only looking at how much a new medium is used, but also at its success in terms of popularity and audience reach. Our findings show that the two platforms are indeed related, mainly because a small political elite dominates both old and new media. Twitter popularity and Twitter activity (albeit to a lesser extent) are higher among powerful politicians. We elaborate on why these findings are so much in line with the normalization hypothesis.     

High-intensity interval training (HIIT) increases insulin-like growth factor-I (IGF-I) in sedentary aging men but not masters’ athletes: an observational study

Introduction: The aim of this investigation was to examine the impact high-intensity interval training (HIIT) on serum insulin-like growth factor-I (IGF-I) in active compared with sedentary aging men.

Methods: 22 lifetime sedentary (SED; 62?±?2 years) and 17 masters’ athletes (LEX; 60?±?5 years) were recruited to the study. As HIIT requires preconditioning exercise in sedentary cohorts, the study required three assessment phases; enrollment (phase A), following preconditioning exercise (phase B), and post-HIIT (phase C). Serum IGF-I was determined by electrochemiluminescent immunoassay.

Results: IGF-I was higher in LEX compared to SED at baseline (p?=?0.007, Cohen’s d?=?0.91), and phase B (p?=?0.083, Cohen’s d?=?0.59), with only a small difference at C (p?=?0.291, Cohen’s d?=?0.35). SED experienced a small increase in IGF-I following preconditioning from 13.1?±?4.7 to 14.2?±?6.0?μg·dl^?1 (p?=?0.376, Cohen’s d?=?0.22), followed by a larger increase post-HIIT (16.9?±?4.4?μg·dl^?1), which was significantly elevated compared with baseline (p?=?0.002, Cohen’s d?=?0.85), and post-preconditioning (p?=?0.005, Cohen’s d?=?0.51). LEX experienced a trivial changes in IGF-I from A to B (18.2?±?6.4 to 17.2?±?3.7?μg·dl^?1 [p?=?0.538, Cohen’s d?=?0.19]), and a small change post-HIIT (18.4?±?4.1?μg·dl^?1 [p?=?0.283, Cohen’s d?=?0.31]). Small increases were observed in fat-free mass in both groups following HIIT (p?d?=?0.32–0.45).

Conclusions: In conclusion, HIIT with preconditioning exercise abrogates the age associated difference in IGF-I between SED and LEX, and induces small improvements in fat-free mass in both SED and LEX.     

Parent–child gender matching and child psychological adjustment after divorce

The present study aimed to determine whether a parent–child gender match would influence child psychological adjustment after divorce. Participants included 69 parents (36 mothers) in active family law litigation to resolve issues related to postdissolution of marriage or time-sharing matters. Participants provided demographic information and completed the Child Behavior Checklist (CBCL; Achenbach, 1991 Achenbach, T. M. (1991). Manual for the child behavior checklist/4–18 and 1991 profile. Burlington, VT: Department of Psychiatry, University of Vermont. [Google Scholar]) to assess their perceptions of their child’s internalizing and externalizing behavior problems. Results demonstrated that internalizing and externalizing behaviors were not affected by whether children spent more time with the same gender parent, opposite gender parent, or split their time equally between both. Comparisons and contradictions between the results in this study and existing research are discussed, as well as practical implications.     

Personality profiles of factitious disorder imposed by mothers: A comparative analysis

Factitious Disorder Imposed by Another (FDIA) can be difficult to expeditiously identify. Understanding personality characteristics of FDIA perpetrators via psychological assessment may decrease the time between initial abuse and identification of FDIA. Personality characteristics of FDIA mother-perpetrators were examined through a comparative analysis of MMPI-2 profiles. It was predicted that mother-perpetrators would have significantly higher overall profile elevations on the MMPI-2 and elevations on specific clinical scales than a comparative control group. Results indicated that mother-perpetrators displayed significantly higher, elevations on the Psychasthenia (Pt) and Schizophrenia (Sc) scales and a trend toward significantly higher elevation on the Psychopathic Deviate (Pd) scale than the control group. These findings, along with the demographic information obtained, establish a preliminary foundation for understanding an overall profile of mother-perpetrators.     

Does childhood family structure help create stratification in adult education and labor market attainment?: An argument for the selectivity perspective

Stratification in opportunities for and attainment of educational credentials, stable and well‐paying jobs, wealth, and socioeconomic status causes problems for both individuals and the societies they live in. It is unclear, however, the extent to which important childhood experiences, such as family structure and transitions, shapes opportunity paths and eventual attainment later in adulthood. The intergenerational transmission literature suggests little if any role of family structure in later attainment, while family scholars and demographers find more compelling evidence that childhood family structures and transitions are influential in adulthood. We argue that both perspectives may be identifying selectivity processes that help explain potential links between families of origin and differences in opportunities to attain education, careers, and status. We then provide suggestions for future work in each of these scholarly traditions to help untangle both the degree to which family structure does or does not affect adult attainment and whether selectivity is the key explanation for any such relationships.