Best management of patients incurring in minor head injury (MHI) while undergoing chronic anticoagulation is a controversial and debated clinical problem [[1], [2], [3], [4], [5], [6], [7]]. Finding a point of equilibrium between caution and avoiding unnecessary radiological examinations and/or in-hospital observation is still a conundrum. In this context, the availability of validated protocols and reliable predictors of prognosis would be of great benefit. In particular, after a first CT-scan [[8], [9], [10], [11]], it remains unclear whether such patients should then be hospitalized for observation and/or undergo a later second CT scan [[12], [13], [14], [15]], given the increase of risk for intracranial injury (ICI) linked to anticoagulation [16,17].

A 2002 guideline from European Federation of Neurological Societies (EFNS) recommends that all anticoagulated patients with MHI should receive an initial CT scan, admission for a 24-h period of close neurologic observation, and then a second CT scan before discharge [18]. In 2012, we tested this guideline on 87 patients receiving warfarin without intracranial lesions on a first CT scan, finding a rate of 6% of delayed ICI (dICI), defined as a second positive head CT scan after a first negative head CT scan [19]. Unfortunately, statistical power was insufficient to analyze multivariable predictors of ICI. Since then, some systematic reviews (SRs) [[20], [21], [22], [23], [24], [25]] have been published, reporting a lower incidence of dICI (0.5–2%). However, most published studies were retrospective and did not report clinical data of the patients. A well-powered prospective cohort study is needed to estimate risk of dICI and identify clinical factors predictive of adverse outcomes.

We measured the incidence of death, admission in hospital, neurosurgery, re-admission to ED, dICI and ICI at the first or second CT in anticoagulated patients following a MHI, who were treated according to EFNS guidelines in our Emergency Department Observational Unit (EDOU). We assessed a number of well-known clinical predictors for poor clinical outcomes, dICI and ICI at the first or second CT scan.