  This paper presents a study protocol for an effectiveness evaluation of
antiandrogenic (NAM) medications (i.e. abiraterone acetate and enzalutamide)
against standard of care in patients suffering from metastatic castrate
resistant prostate cancer. The study protocol takes stock in the Rubin Causal
Model for observational data in using historical comparisons for the analysis
on three outcomes: mortality, pain and skeleton related events. We restrict the
evaluation to 1,285 NAM patients with a prostate cancer diagnosis after June
2012 and find the comparisons in the group of men that had a prostate cancer
diagnosis between June 2008 and June 2010. The rich registry data and the lack
of NAMs as an option for the comparisons provide support for the validity of
the design. However, while the design yields balance on the observed
covariates, one cannot discard the possibility that unobserved confounders are
not balanced. Thus, sensitivity analyses are suggested.

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