Addressing bias in observational studies of alcohol withdrawal syndrome: a call to the field.
WE READ WITH interest the recent systematic review and meta-analysis on alcohol withdrawal syndrome (Goodson et al., 2014). We applaud the efforts of Goodson and colleagues (2014) to seek further insights about this morbid condition but we would like to sound a cautionary alarm. The hard work of Goodson and others in the field is hindered by a flawed research base. Appropriately, almost all studies in this field use observational methods. Unfortunately, they typically do not employ standard safeguards in observational research designed to protect against potential biases. This presents a substantial challenge to progress in the understanding of this clinical state. Until researchers address these biases with rigorous studies, research will continue to produce inconsistent results that preclude consensus regarding how to predict severe alcohol withdrawal syndrome and thus provide patients with the most effective and the safest therapy. Observational research on alcohol withdrawal syndrome is particularly prone to susceptibility, exposure suspicion, and diagnostic suspicion bias (Fiellin et al., 1998; Sackett, 1979). Despite well-accepted strategies to address these biases, alcohol researchers have nearly uniformly failed to create inception cohorts, use standard operational definitions for risk factors and outcomes, or employ blinding of risk factors or outcomes. Inception cohorts allow researchers to include and compare patients at a similar point in their disease process. Operational definitions allow researchers to indicate the explicit criteria that were used in determining risk factors and outcomes, and Goodson and colleagues’ (2014) methods appropriately excluded studies in which these were unclear. Blinding minimizes the likelihood that knowledge of risk factors or outcomes will influence the determination of the basic elements of the research. We fear that clinicians and policy makers run the risk of basing decisions on flawed evidence (despite systematic reviews and meta-analyses) until these deficiencies in the basic science of observational research are addressed in subsequent research on alcohol withdrawal syndrome.