Scientific evaluation of benefit and risk is especially important to the physician community utilizing medical devices to treat symptomatic vascular disease. As there are multiple avenues for publication, physicians are potentially exposed to various levels of scientific rigor so we must critically evaluate any data on patient treatment. In our assessments we must take into account that any valid assessment of clinical outcomes and treatment effect is dependent on proper study design, which certainly includes the likelihood of ascertainment bias, as well as a high level of reliable follow-up data. As often is the case when utilizing non-blinded randomized data one must be on the look-out for ascertainment bias which refers to the situation when the results of a clinical trial are distorted by knowledge about how patients were treated either because of lack of blinding or improper allocation concealment [1]. However, of all potential flaws, incomplete follow-up is particularly dangerous as it may go unnoticed within even flawed Kaplan-Meier estimates [2,3].