Critically ill patients encompass an enormously heterogeneous population and, as such, therapeutic interventions, including drug therapy, can produce multiple outcomes in different patient subgroups. For example, researchers not only look for an ‘average effect’ of a drug on a typical patient, but also seek to understand individual variability. The presence of variability impacts significantly on the success of clinical trials and failure to identify this variability can result in the clinical trial being under-powdered to detect a treatment effect. For clinicians, failure to recognize variability can result in unintended toxicity or excessive harm in certain patients. Hence, understanding variability is critically important in both research and clinical practice.
Rethinking Sepsis: New Insights from Gene Expression Profiling Studies