Ten reasons why we should NOT use severity scores as entry criteria for clinical trials or in our treatment decisions

Objective: Severity scores such as Acute Physiology and Chronic Health Evaluation II have been advocated as entry criteria for clinical trials and in clinical decision-making. We present ten reasons why we believe this approach is not appropriate and may even be detrimental. Data Sources. Available relevant literature from authors' personal databases and personal knowledge of past and future clinical trial development. Data Synthesis: Severity scores were not designed for use in individual patients or for therapeutic decision-making for specific interventions. Difficulties with the time window needed to calculate these scores and the need to administer therapies early further limit their use in this context. The complex nature of the scores makes it difficult to use them at the bedside and there is considerable inter-observer variability in score calculation. Inclusion of chronic health and age points in severity scores may prevent younger, previously healthy patients, with similar acute physiological dysfunction and therefore total lower severity scores, from trial inclusion or from receiving therapies that may be beneficial. Conclusions: We believe severity of illness scores are poor surrogates for risk stratification and should not be used as a criterion for patient enrollment into clinical trials or as the basis for individual treatment decisions. (Crit Care Med 2010; 38: 283-287)