Should all anticoagulated patients with head injury receive a CT scan? Decision-analysis modelling of an observational cohort

Objectives: It is not currently clear whether all anticoagulated patients with a head injury should receive CT scanning or only those with evidence of traumatic brain injury (eg, loss of consciousness or amnesia). We aimed to determine the cost-effectiveness of CT for all compared with selective CT use for anticoagulated patients with a head injury. Design: Decision-analysis modelling of data from a multicentre observational study. Setting: 33 emergency departments in England and Scotland. Participants: 3566 adults (aged >= 16 years) who had suffered blunt head injury, were taking warfarin and underwent selective CT scanning. Main outcome measures: Estimated expected benefits in terms of quality-adjusted life years (QALYs) were the entire cohort to receive a CT scan; estimated increased costs of CT and also the potential cost implications associated with patient survival and improved health. These values were used to estimate the cost per QALY of implementing a strategy of CT for all patients compared with observed practice based on guidelines recommending selective CT use. Results: Of the 1420 of 3534 patients (40%) who did not receive a CT scan, 7 (0.5%) suffered a potentially avoidable head injury-related adverse outcome. If CT scanning had been performed in all patients, appropriate treatment could have gained 3.41 additional QALYs but would have incurred 193 pound 149 additional treatment costs and 130 pound 683 additional CT costs. The incremental cost-effectiveness ratio of 94 pound 895/QALY gained for unselective compared with selective CT use is markedly above the threshold of 20-30 pound 000/QALY used by the UK National Institute for Care Excellence to determine cost-effectiveness. Conclusions: CT scanning for all anticoagulated patients with head injury is not cost-effective compared with selective use of CT scanning based on guidelines recommending scanning only for those with evidence of traumatic brain injury.