Mediation Analysis with Survival Outcomes: Accelerated Failure Time vs. Proportional Hazards Models.

Objective: Survival time is an important type of outcome variable in treatment research. Currently, limited guidance is available regarding performing mediation analyses with survival outcomes, which generally do not have normally distributed errors, and contain unobserved (censored) events. We present considerations for choosing an approach, using a comparison of semi-parametric proportional hazards (PH) and fully parametric accelerated failure time (AFT) approaches for illustration.

The Personalized Advantage Index: translating research on prediction into individualized treatment recommendations. A demonstration.

Background: Advances in personalized medicine require the identification of variables that predict differential response to treatments as well as the development and refinement of methods to transform predictive information into actionable recommendations.

Objective: To illustrate and test a new method for integrating predictive information to aid in treatment selection, using data from a randomized treatment comparison.

Method: Data from a trial of antidepressant medications (N = 104) versus cognitive behavioral therapy (N = 50) for Major Depressive Disorder were used to produce predictions of post-treatment scores on the Hamilton Rating Scale for Depression (HRSD) in each of the two treatments for each of the 154 patients.

Understanding processes of change: how some patients reveal more than others-and some groups of therapists less-about what matters in psychotherapy.

Objective: We identify difficulties researchers encounter in psychotherapy process-outcome investigations, and we describe several limitations of the popular "variance accounted for" approach to understanding the effects of psychotherapy.

Methods & Results: Using data simulations, we show how the expected correlation between an excellent measure of therapy quality and outcome would be surprisingly small (approximately .25) under conditions likely to be common in psychotherapy research.

Mediation analysis: a retrospective snapshot of practice and more recent directions.

R. Baron and D. A.

Sequence of improvement in depressive symptoms across cognitive therapy and pharmacotherapy.

Background: The authors examined the patterns of improvement in cognitive and vegetative symptoms of major depression in individuals treated with cognitive therapy (CT) or pharmacotherapy (PT).

Method: Outpatients diagnosed with major depressive disorder (n=180) were randomized to receive either CT or PT. Cognitive and vegetative symptoms of major depression were measured by the Beck Depression Inventory-II at baseline and regularly throughout 16 weeks of treatment.

Bias resulting from the use of 'assay sensitivity' as an inclusion criterion for meta-analysis.

Assay sensitivity has been proposed as a criterion for including psychiatric clinical outcome studies in meta-analyses. The authors assess the performance of assay sensitivity as a method for determining study appropriateness for meta-analysis by calculating expected standard drug vs placebo effect sizes for various combinations of high quality and flawed studies. In the absence of flawed studies, expected effect sizes are close to unbiased only when sample sizes are very large.

Reducing exposure of clinical research subjects to placebo treatments.

The ethics of pill placebo and placebo psychotherapy conditions in clinical research are controversial. Even when not life threatening, mental disorders dramatically diminish the quality of life. Pill-placebo conditions in drug treatment research have been justified on the grounds that a placebo versus standard drug comparison is necessary to test the quality of the study, viz.