Evolving statistical methods to facilitate evaluation of the causal association between erythropoiesis-stimulating agent dose and mortality in nonexperimental research: strengths and limitations.

Findings from randomized controlled trials examining the efficacy of therapy with erythropoiesis-stimulating agents (ESAs) to normalize hemoglobin levels in patients with chronic kidney disease or kidney failure have raised questions regarding the safety of this class of drugs. However, no trial to date has specifically assessed the safety of ESA-dosing algorithms used to achieve the lower hemoglobin targets typically using in clinical practice. Although a wealth of nonexperimental data is available for dialysis patients, analyses based on these data are more susceptible to confounding bias than randomized controlled trials. Conducting valid pharmacoepidemiologic studies of drug effects in hemodialysis patients is complicated by the extent of their comorbidities, frequent hospitalizations, various concomitant medications, and an exceedingly high mortality rate. The need for greater ESA doses for the treatment of anemia in sicker patients potentially and plausibly generates confounding by indication, the control of which is complicated by the presence of time-dependent confounding. Here, we describe sources of bias in nonexperimental studies of ESA therapy in hemodialysis patients and critically appraise analytical methods that may help minimize bias in such studies.

[Drug trials in humans. Risks in the light of the London catastrophe]. / Arzneimitteltestung am Menschen. Die Risiken im Licht der Katastrophe von London.

London's first-in-man drug trial with the monoclonal anti-CD28 antibody TGN1412 used for the treatment of oncological and autoimmune diseases resulted in a disaster with life-threatening adverse events in the volunteers triggered by an unexpected cytokine storm. Potential mistakes and consequences from this trial are highlighted in the general context of drug development and its risks. Risks in drug testing are not only found for high risk substances, such as TGN1412, or in the critical first-in-man phase, but can sometimes be detected only in later phases of the clinical testing, such as the phase 3 submission studies, or even after market authorization, as for example was the case in the cyclooxygenase-2-inhibitor rofecoxib (Vioxx) used for the treatment of rheumatic diseases and acute pain. Regulatory requirements to minimize risks in drug trials, however, have improved substantially over the last decades. Moreover, in light of the London incident these are being continuously modified with great diligence.