“Clinical prediction rules” or “decision rules” are designed to suggest a pathway of probability of a pathological condition and help the clinician choose a diagnostic or therapeutic course of action. The rules reduce the uncertainty inherent in medical practice—for example, in emergency medicine and trauma—by appraising clinical findings to make predictions. Because these rules affect patient care and health costs, they must be carefully evaluated before implementation. For this purpose, guidance and methodological standards exist for users and developers of clinical prediction rules.1 2 In the linked cluster randomised controlled study (doi:10.1136/bmj.b4146),3 Steill and colleagues assess the effectiveness of a knowledge translation strategy to implement the validated Canadian c-spine rule in 12 emergency departments in Canada.

Specific algorithms and prediction rules for the initial assessment of patients with cervical spine injury have been proposed in the literature. Since the early 1990s, the National Emergency X-Radiography Utilization Study’s low risk criteria (NEXUS)4 and the …