Recently, in a series of papers, a method based on pseudo-values has been proposed for direct regression modeling of the survival function, the restricted mean and cumulative incidence function with right censored data. The models, once the pseudo-values have been computed, can be fit using standard generalized estimating equation software. Here we present SAS macros and R functions to compute these pseudo-values. We illustrate the use of these routines and show how to obtain regression estimates for a study of bone marrow transplant patients.
We extend the definition of the controlled direct effect of a point exposure on a survival outcome, other than through some given, time-fixed intermediate variable, to the additive hazard scale. We propose two-stage estimators for this effect when the exposure is dichotomous and randomly assigned and when the association between the intermediate variable and the survival outcome is confounded only by measured factors, which may themselves be affected by the exposure. The first stage of the estimation procedure involves assessing the effect of the intermediate variable on the survival outcome via Aalen's additive regression for the event time, given exposure, intermediate variable and confounders. The second stage involves applying Aalen's additive model, given the exposure alone, to a modified stochastic process (i.e. a modification of the observed counting process based on the first-stage estimates). We give the large sample properties of the estimator proposed and investigate its small sample properties by Monte Carlo simulation. A real data example is provided for illustration
A high educational attainment is shown to have a positive effect on second birth rates for Danish one-child mothers during the period 1981-94. We examine whether a timesqueeze is a possible explanation: due to the longer enrolment in the educational system, highly educated women have less time at their disposal in order to get the desired number of children. Also, we examine to what extent the partnerŠs education can explain some of the positive effect. We find no evidence that the positive effect of education is due to a time-squeeze nor to a partner effect.
This study aims to evaluate the incidence of breast cancer after risk-reducing mastectomy (RRM) in healthy BRCA mutation carriers. This study is a long-term follow-up of 307 BRCA mutation carriers of whom 96 chose RRM. None of the study participants had a previous history of breast or ovarian cancer nor had they undergone RRM or risk-reducing bilateral salpingo-oophorectomy (BSO) prior to the time of BRCA testing. The annual incidence of post-mastectomy breast cancer was 0.8% compared with 1.7% in the non-operated group. Implications of these findings in relation to genetic counseling and future management are discussed.
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