Analyzing survival data in conjunction with time-dependent surrogate endpoints in clinical trials

Current survival techniques do not provide a good method for handling clinical trials with a large percent of censored observations. This research proposes using time-dependent surrogates of survival as outcome variables, in conjunction with observed survival time, to improve the precision in comparing the relative effects of two treatments on the distribution of survival time. This is in contrast to the standard method used today which uses the marginal density of survival time, T. only, or the marginal density of a surrogate, X, only, therefore, ignoring some available information. The surrogate measure, X, may be a fixed value or a time-dependent variable, X(t). X is a summary measure of some of the covariates measured throughout the trial that provide additional information on a subject's survival time. It is possible to model these time-dependent covariate values and relate the parameters in the model to the parameters in the distribution of T given X. The result is that three new models are available for the analysis of clinical trials. All three models use the joint density of survival time and a surrogate measure. Given one of three different assumed mechanisms of the potential treatment effect, each of the three methods improves the precision of the treatment estimate.     

What do we know about the social networks of single parents who do not use supportive services?

The role that social support and social networks play in mediating isolation and stress experienced by vulnerable families is well established. However, a major issue facing supportive human services is to find and engage families with limited social networks and link them to supports that could improve outcomes for their families. This paper reports on the results of in‐depth interviews with 20 sole parents with children aged under 5 who were not well connected to services. It documents their social networks with the use of a social network map. Using a social capital lens, the analysis attempts to differentiate the different relationships in the participants' lives. Most participants were not satisfied with their informal networks, with conflicted or ambivalent reliance on family, absence of support and community engagement and fragility of informal networks. Although this group of isolated mothers does encounter the formal service system, the opportunities to increase and strengthen their networks do not eventuate. Better understanding of the nature and extent of social networks can inform practitioners and policy‐makers of the critical factors needed to increase service use for parents with limited resources.