To review scoping was conducted using established methodological frameworks for evidence mapping11,12, with detailed methodological procedures provided in the supplementary materials to ensure transparency and reproducibility. The protocol for this scoping review was not registered prospectively. However, this scoping review followed Arksey and O’Malley’s framework, with methodological refinements informed by Levac et al. and the Joanna Briggs Institute guidance.
This approach was selected to allow for a broad identification of knowledge gaps and variation in the available evidence, especially given that critically ill populations are often excluded from randomized trials13,14.
The rationale for this methodology was to integrate evidence from heterogeneous ICU populations and designs on bleeding risk determinants without conducting quantitative synthesis or comparative effectiveness analysis. Reporting was guided by the Preferred Reporting Items for Systematic Reviews and Meta-analysis extension for Scoping Reviews14. A Preferred Reporting Items for Systematic Reviews and Meta-analysis flow diagram outlining the study selection process is presented in the supplementary materials.
Eligibility criteria
Eligibility included reviews, randomized controlled trials and non-randomized controlled trials, observational studies, guidelines or consensus documents describing NOACs-related bleeding endpoints. Studies were required to include adult critically ill patients, intensive care unit populations, or clinical conditions directly related to a critical illness (eg, sepsis, acute organ dysfunction) or invasive procedures. Studies targeting stable outpatient populations were excluded. Table 1 summarizes the eligibility criteria.
| Domain | Inclusion Criteria | Exclusion Criteria | Reference |
| Population | Adult patients receiving NOACs in critical illness, ICU settings | Pediatric populations, pregnant patients, and stable outpatient populations | 11, 13 |
| Intervention/Exposure | Use of NOACs (apixaban, rivaroxaban, dabigatran, edoxaban), including continuation, interruption, or management during critical illness | Studies focusing on vitamin K antagonists or parenteral anticoagulants without NOAC data | 12 |
| Outcomes of Interest | Bleeding events, bleeding risk factors, reversal strategies, and resumption of anticoagulants | Studies not reporting bleeding-related outcomes | 13 |
| Study design | Randomized controlled trials, observational studies, reviews, and guidelines | Case reports, editorials, conference abstracts, and commentaries | 11, 12 |
| Clinical Context | ICU populations and conditions relevant to critical illness (sepsis, invasive procedures, organ dysfunction) | Studies without relevance to critical illness or ICU practice | 13 |
| Language and publication type | English and peer-reviewed publications | Non-English publications and non-peer-reviewed sources | 12 |
Table 1: Eligibility criteria for study selection Summary of inclusion and exclusion criteria applied to studies based on population, intervention or exposure (NOAC use), outcomes of interest, study design, clinical context, and publication characteristics..
Search strategy and information sources
Structured search queries (increasing in complexity) were used to search major biomedical databases (PubMed, Embase, and Web of Science), covering the period from January 2009 to March 2025. An updated search was conducted through March 2025 to find more recent studies. The search strategy was a combination of controlled vocabulary (MeSH/Emtree) and free-text terms for NOACs, bleeding or haemorrhagic complications, and critical illness or intensive care, combined using Boolean operators. Additional articles were screened in the reference lists of relevant articles. Duplicates were removed by using reference management software before screening. Full strategy (including Boolean operators, database-specific filters, and date limits) is available in the Supplementary Materials. The search was limited to studies published in English and involving human subjects. Given the scoping nature of the review, no limits were placed on study design. Furthermore, this review did not comprehensively include gray literature sources such as conference abstracts, theses, and non-peer-reviewed reports. The inclusion of guidance documents and consensus statements, where relevant, ensured an all-encompassing approach regarding clinical recommendations.
Selection of study and charting of data.
Two reviewers independently performed study selection at both title/abstract screening and full-text review stages. Reviewer discrepancies were resolved through discussion and, if necessary, consultation with a third reviewer. Two reviewers independently extracted data using a standardized data charting form and cross-verified to ensure consistency. Furthermore, study screening and selection were facilitated by reference management software for organizing records and duplicate removal.
Results were synthesized narratively applying scoping review methodology due to considerable heterogeneity in study design, patient populations, and reported outcomes.
Database searching and reference screening
Database searching and reference screening identified 1,050 records. After duplicates were removed (n = 607), based on title and abstract, 443 studies were screened, of which 139 were excluded. We screened 304 full-text articles for eligibility, excluding 254 due to low relevance to ICU settings or bleeding outcomes. This scoping review ultimately included 50 studies (Supplementary Figure 1S).
The studies included were primarily observational, with randomized trials and secondary literature (narrative reviews and clinical guidelines). Much of the evidence came from noncritically ill populations or retrospective analysis, and there is little prospective data specific to the ICU. The included studies differed in study design, patient populations, and definitions for bleeding outcomes.
The evidence included was mainly in the form of secondary literature (e.g., narrative reviews and clinical guidelines) with a smaller number of primary studies directly addressing NOACs-associated bleeding events in critically ill patients. This means that existing evidence is scarce and largely based on extrapolated data or expert opinion.
Clinical situations of NOACs use in the ICU
NOACs therapy can be given to patients in the ICU as continuation of chronic therapy or for acute thromboembolic events in the setting of hospitalization. Common ICU scenarios include atrial fibrillation, venous thromboembolism, cancer-associated thrombosis and perioperative anticoagulation management15,16. Often, NOAC therapy is continued in the setting of acute physiological compromise due to the absence of ICU-specific guidelines and unease with regard to thromboembolic reoccurrence17.
Critical illness often requires invasive procedures, temporary discontinuation of anticoagulation, or bridging strategies, all making NOAC management challenging7. Furthermore, alterations in gastrointestinal absorption, enteral feeding intolerance, as well as drug–drug interactions with antimicrobials, antifungals, and antiarrhythmic agents corrode the safe use of NOACs in ICU5,18. These factors lead to significant interpatient variability in anticoagulant exposure, which in turn imposes considerable uncertainty in dosing and bleeding risk among critically ill patients19. Such variability underscores the lack of standardized ICU-specific anticoagulation treatment strategies, implying that all critically ill patients should undergo an individualized risk assessment. In most available studies, these clinical scenarios exhibit heterogeneity in terms of thromboembolic risk and