Clinical research study
Scores to Predict Major Bleeding Risk During Oral Anticoagulation Therapy: A Prospective Validation Study

https://doi.org/10.1016/j.amjmed.2012.04.005Get rights and content

Abstract

Background

Clinical scores may help physicians to better assess the individual risk/benefit of oral anticoagulant therapy. We aimed to externally validate and compare the prognostic performance of 7 clinical prediction scores for major bleeding events during oral anticoagulation therapy.

Methods

We followed 515 adult patients taking oral anticoagulants to measure the first major bleeding event over a 12-month follow-up period. The performance of each score to predict the risk of major bleeding and the physician's subjective assessment of bleeding risk were compared with the C statistic.

Results

The cumulative incidence of a first major bleeding event during follow-up was 6.8% (35/515). According to the 7 scoring systems, the proportions of major bleeding ranged from 3.0% to 5.7% for low-risk, 6.7% to 9.9% for intermediate-risk, and 7.4% to 15.4% for high-risk patients. The overall predictive accuracy of the scores was poor, with the C statistic ranging from 0.54 to 0.61 and not significantly different from each other (P = .84). Only the Anticoagulation and Risk Factors in Atrial Fibrillation score performed slightly better than would be expected by chance (C statistic, 0.61; 95% confidence interval, 0.52-0.70). The performance of the scores was not statistically better than physicians' subjective risk assessments (C statistic, 0.55; P = .94).

Conclusion

The performance of 7 clinical scoring systems in predicting major bleeding events in patients receiving oral anticoagulation therapy was poor and not better than physicians' subjective assessments.

Section snippets

Study Design and Setting

This prospective cohort study was conducted in the Internal Medicine and Ambulatory Care and Community Medicine Departments of Lausanne University Hospital, Switzerland. The protocol was approved by the institutional review board, and all participants gave their informed consent.

Study Population

We included all consecutive patients aged ≥ 18 years who were receiving oral anticoagulant therapy at the time of hospital discharge or at presentation in the ambulatory clinic from January 1, 2008, to March 31, 2009.

Study Population

Of 650 consecutive patients receiving oral anticoagulant therapy who were screened between January 1, 2008, and March 31, 2009, we excluded 132 patients (20.8%) because of refusal or inability to give informed consent. We further excluded 3 patients (0.5%) who withdrew consent within a few weeks of the start of the study, leaving a final sample of 515 patients. The 3 patients who withdrew consent did not have a bleeding event before withdrawal. Excluded patients were significantly older than

Discussion

We found that existing clinical scores poorly predict major bleeding events in unselected internal medicine patients receiving oral anticoagulant therapy. The C statistics ranged from 0.54 to 0.61 with 95% CIs crossing 0.50 for all scores except the ATRIA score. This suggests that the discriminatory power was not better than would have been expected due to chance alone for all scores except the ATRIA score, which performed only slightly better.19 Furthermore, overall score performances were not

Conclusions

Our results indicate that clinical scores poorly predict the risk of major bleeding in unselected patients receiving oral anticoagulant therapy. Score performances do not seem to be better than physicians' subjective assessments. Novel clinical risk assessment methods that accurately and reliably predict the risk of major bleeds among those receiving oral anticoagulant therapy are needed.

Acknowledgments

The authors thank Dr Jeffrey Schnipper, assistant professor of medicine at the Harvard School of Medicine (Boston, MA), for careful review of the article. Dr J. Schnipper played no role in the design or conduct of the study, or in the collection, management, or interpretation of the data.

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    Funding: This study was supported by an intramural grant (CardioMet) from the University Hospital Lausanne, Switzerland. Dr Jacques Donzé was supported by grants provided by the Swiss National Science Foundation (PBLAP3-131814 and PBLAP3-136815). The providers of the grants played no role in the design or conduct of the study, or in the collection, management, or interpretation of the data.

    Conflict of Interest: None.

    Authorship: All authors had access to the data and played a role in writing this manuscript.

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