Clinical infectious diseases : an official publication of the Infectious Diseases Society of America
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Clinical trials of nosocomial pneumonia can include patients with hospital-acquired pneumonia, ventilator-associated pneumonia, and health care-associated pneumonia. All study participants should meet a clinical definition of infection and have some microbiologic confirmation of infection and its etiology. If the trial is to reflect clinical practice and to be practical to conduct, insistence that all patients have bronchoscopic quantitative cultures performed may not be practical. ⋯ All trials should include a protocol to control for standards of care, including timing of initial therapy, recent antibiotic use, local microbiology patterns, duration of therapy, and the use of a de-escalation therapy strategy. Blinding of a trial may not be required if studying a new agent that is more active against multidrug-resistant pathogens than against currently available comparators. Any new agent should meet a noninferiority end point for 30-day mortality, but if superiority is a goal of trial design, end points could be microbiologic eradication, time to microbiologic eradication, prolonged duration of therapy, need to modify initial therapy, and serial evaluation of the arterial oxygen tension to fractional inspired oxygen ratio.
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For treatment studies of an infectious disease, such as pneumonia, microbiologic eradication is the logical primary end point. Several problems for pneumonia in general and several more specific to VAP preclude the use of microbiologic eradication as a primary end point. These problems include no positive culture result at baseline, difficulty distinguishing colonization from infection on baseline cultures, no specimen available for testing when determining cure, and induction of colonization by antibiotic treatment. ⋯ Although promising, especially for open-label studies focused on multidrug-resistant pathogens, further research is needed before serial quantitative cultures can be used to define microbiologic failure. Of the biomarkers, procalcitonin level may be a valuable adjunct to clinical evaluation but cannot be a primary end point alone. A decreasing or low procalcitonin level after initiation of antibiotic treatment correlates well with bacterial eradication.
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There is an increasing focus on having quality systems in place during the planning stages of clinical trials. Such systems require the development and implementation of standards for each step. Although this is not imposing something totally new on clinical research, a systematic approach will produce a more reliable and useful end product--high-quality data obtained without compromising the protection of human subjects' rights and welfare. A suggested quality system with standards for each step is addressed in this article.