noun “the branch of medicine which deals with the incidence, distribution, and possible control of diseases and other factors relating to health”

Epidemiology is the study and analysis of the patterns, causes, and effects of health and disease conditions in defined populations. It is the cornerstone of public health, and shapes policy decisions and evidence-based practice by identifying risk factors for disease and targets for preventive healthcare. Major areas of epidemiological study include disease causation, transmission, outbreak investigation, disease surveillance, forensic epidemiology and screening, biomonitoring, and comparisons of treatment effects such as in clinical trials.

Despite over two million people attending NSW emergency departments with undifferentiated disease, ranging from sprained ankles and upper respiratory tract infections to acute coronary syndromes, major trauma and cardiac arrest, there is no central mechanism to collect and analyse clinical data. This has lead to a situation where both clinicians and policy-makers are bereft of the basic information and evidence required to make outcomes-based patient care decisions. Diagnostic strategies and therapeutic interventions within the prehospital and emergency settings are therefore made based on best available evidence, but with minimal outcome data to reinforce or modify practice.