Criteria for response in patients in clinical trials of empiric antibiotic regimens for febrile neutropenia. Is there agreement?

A review of the literature on the criteria of response in patients on clinical trials of empiric antibiotic therapy revealed that there are at least three definitions utilized worldwide along with individual investigator definitions. The main definitions include definitions by Pizzo from the NCI, by the EORTC Antimicrobial group and by the Immunocompromised Host Society. The outcome in clinical trials can be affected by the definition used if the major endpoint in the study compares response rates of two or more initial empiric antimicrobial regimens for febrile neutropenia. Survival based definitions (Pizzo) are very useful but may not identify which regimen required the least number of modifications during the critical initial 3-5 days of trial. Evaluations later in the course of the febrile episode will not likely be influenced by these definitions as most patients with prolonged and severe neutropenia will eventually require modifications of therapy. A consensus to use a single response definition is necessary to allow comparisons and meta-analysis of results with specific antibiotic regimens for febrile neutropenia. These must be enforced by editors of major medical journals to truly allow this to happen.