Evidence-based decision-making (part 1): Origins and evolution in the health sciences.

Evidence is defined as data on which a judgment or conclusion may be based. In the early 1990s, medical clinicians pioneered evidence-based decision-making. The discipline emerged as the use of current best evidence in making decisions about the care of individual patients. The practice of evidence-based medicine required the integration of individual clinical expertise with the best available, external clinical evidence from systematic research and the patient's unique values and circumstances. In this context, evidence acquired a hierarchy of strength based upon the method of data acquisition. Subsequently, evidence-based decision-making expanded throughout the allied health field. In public health, and particularly for populations in crisis, three major data-gathering tools now dominate: (1) rapid health assessments; (2) population based surveys; and (3) disease surveillance. Unfortunately, the strength of evidence obtained by these tools is not easily measured by the grading scales of evidence based medicine. This is complicated by the many purposes for which evidence can be applied in public health: strategic decision-making, program implementation, monitoring, and evaluation. Different applications have different requirements for strength of evidence as well as different time frames for decision-making. Given the challenges of integrating data from multiple sources that are collected by different methods, public health experts have defined best available evidence as the use of all available sources used to provide relevant inputs for decision-making.