Studying outcomes of intensive care unit survivors: the role of the cohort study

Background: As research focuses on long-term patient outcomes and the "real world" effectiveness of intensive care unit (ICU) therapies, the cohort study is increasingly being used in critical care research. Methods: Using examples of prior cohort studies in intensive care, we review the key elements of this research design and evaluate its advantages and limitations for critical care research. Furthermore, through a systematic search of the literature we summarize data from 70 prior published cohort studies of medium- and long-term outcomes in adult critical care medicine. Discussion: This research demonstrates that the prospective cohort study is a powerful research design that has not been fully leveraged to assess relationships between exposures and long-term outcomes of ICU survivors. Conclusions: We make recommendations for the design of future cohort studies to maximize the impact of this research in improving the long-term outcomes of critically ill patients.