In our study of 2,362 ED visits involving head trauma and OAC therapy, we identified five cases of d-ICH, accounting for 0.2% of the visits (95% CI [0.07–0.5%]). Of these, two cases (0.08%, [95% CI 0.01–0.3%]) were classified as clinically relevant, due to their association with mortality, yet neither required ICU admission nor neurosurgery. None of the observed d-ICH cases were diagnosed within the 24-hour observation period recommended by SNC and the Austrian consensus document. On the contrary, the few cases of d-ICH in our study were diagnosed four or more days after their initial ED visit, aligning with Chenoweth et al.’s findings where two of three d-ICH cases were detected after 24 hours19. This suggests that the 24-hour observation period may be inadequate in detecting d-ICH. Our findings challenge the utility of currently recommended 24-hour observation period by the Scandinavian Neurotrauma Committee (SNC) guideline and the Austrian expert consensus document. Our results lend support to other guidelines that do not mandate such observation6–9,12.
Mandatory observation for d-ICH in the ED and in-hospital units carries significant costs and adds a burden on already strained healthcare resources. In 2012, the cost in the USA was estimated at 1,000,000 USD to detect a single case of d-ICH, and this cost is likely much higher now20. Additionally, the typical patient demographic for OAC therapy – older and frail individuals – may be harmed by even short-term hospitalizations13–16. Furthermore, other concerns could be present that are of higher individual value than in-hospital observation for the rare event of d-ICH.
Previous studies assessing the risk of d-ICH in anticoagulated patients have utilized diverse methodologies and patient populations, making it difficult to determine its true prevalence. The latest meta-analysis by Puzio et al., conducted after the introduction of direct oral anticoagulant (DOAC) therapies, reported a 2.3% incidence of d-ICH in patients treated with OAC who suffered a blunt head injury21. However, several more recent studies, reflecting the increased useof DOACs compared to warfarin, generally suggest incidence rates of ≤ 1%22,23,23–25. The variance in incidence rates between studies could be attributed not only to differences in follow-up methodology but also to misdiagnosis. For instance, Verschoof et al. found that 66% of their d-ICH cases were actually erroneous, with subtle ICH noted retrospectively on initial CT scans26. The advent of advanced CT technology may reduce the incidence of d-ICH by enabling the detection of minimal ICH on initial scans27.
Our study, which observed a d-ICH incidence of 0.2% (95% CI [0.07–0.5%]), was not designed to find all cases of d-ICH, being a retrospective cohort without structured follow-up or imaging. However, our findings are in line with recent studies that report a low incidence of d-ICH.
Many cases of d-ICH are minor and often managed conservatively. Clinically important d-ICH, which requires neurosurgery or causes death, appear to be very rare. Puzio et al.’s meta-analysis indicated a crude risk of death from d-ICH at 0.33% and d-ICH-related neurosurgical interventions at 0.13%1. Several newer studies have shown that important interventions, such as neurosurgery, is extremely rare, with many reporting no neurosurgical interventions across various patient populations14,16,22–25. This aligns with the results of our study, where we found no d-ICH related neurosurgical interventions (0.0%, 95% CI [0.0-0.03%]) or ICU admissions (0.0%, 95% CI [0.0-0.03%]), and a low mortality rate (0.08%, [95% CI 0.01–0.3%]).
Given the low incidence of clinically relevant d-ICH, and considering that very few cases seem appropriate for neurosurgical intervention, it has been proposed that mandatory observation for OAC treated patients should be omitted28. This perspective is mirrored in more recently reviewed guidelines, like those from NICE and French recommendations, which do not advocate for routine observation following a negative initial CT9,12. This opinion, reinforced by recent evidence including findings from this study, supports reconsidering the necessity of mandatory observation and calls for a revision of the SNC guidelines.