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Validation of risk stratification schemes for predicting stroke and thromboembolism in patients with atrial fibrillation: nationwide cohort study

BMJ 2011; 342 doi: https://doi.org/10.1136/bmj.d124 (Published 31 January 2011) Cite this as: BMJ 2011;342:d124
  1. Jonas Bjerring Olesen, research fellow1,
  2. Gregory Y H Lip, professor2,
  3. Morten Lock Hansen, research fellow1,
  4. Peter Riis Hansen, research director1,
  5. Janne Schurmann Tolstrup, research director3,
  6. Jesper Lindhardsen, research fellow1,
  7. Christian Selmer, research fellow1,
  8. Ole Ahlehoff, research fellow1,
  9. Anne-Marie Schjerning Olsen, research fellow1,
  10. Gunnar Hilmar Gislason, research director1,
  11. Christian Torp-Pedersen, professor1
  1. 1Department of Cardiology, Copenhagen University Hospital Gentofte, 2900 Hellerup, Denmark
  2. 2University of Birmingham Centre for Cardiovascular Sciences, City Hospital, Birmingham B18 7QH, UK
  3. 3National Institute of Public Health, 1399 Copenhagen K, Denmark
  1. Correspondence to: J Olesen jo{at}heart.dk
  • Accepted 28 December 2010

Abstract

Objectives To evaluate the individual risk factors composing the CHADS2 (Congestive heart failure, Hypertension, Age≥75 years, Diabetes, previous Stroke) score and the CHA2DS2-VASc (CHA2DS2-Vascular disease, Age 65-74 years, Sex category) score and to calculate the capability of the schemes to predict thromboembolism.

Design Registry based cohort study.

Setting Nationwide data on patients admitted to hospital with atrial fibrillation.

Population All patients with atrial fibrillation not treated with vitamin K antagonists in Denmark in the period 1997-2006.

Main outcome measures Stroke and thromboembolism.

Results Of 121 280 patients with non-valvular atrial fibrillation, 73 538 (60.6%) fulfilled the study inclusion criteria. In patients at “low risk” (score=0), the rate of thromboembolism per 100 person years was 1.67 (95% confidence interval 1.47 to 1.89) with CHADS2 and 0.78 (0.58 to 1.04) with CHA2DS2-VASc at one year’s follow-up. In patients at “intermediate risk” (score=1), this rate was 4.75 (4.45 to 5.07) with CHADS2 and 2.01 (1.70 to 2.36) with CHA2DS2-VASc. The rate of thromboembolism depended on the individual risk factors composing the scores, and both schemes underestimated the risk associated with previous thromboembolic events. When patients were categorised into low, intermediate, and high risk groups, C statistics at 10 years’ follow-up were 0.812 (0.796 to 0.827) with CHADS2 and 0.888 (0.875 to 0.900) with CHA2DS2-VASc.

Conclusions The risk associated with a specific risk stratification score depended on the risk factors composing the score. CHA2DS2-VASc performed better than CHADS2 in predicting patients at high risk, and those categorised as low risk by CHA2DS2-VASc were truly at low risk for thromboembolism.

Footnotes

  • Contributors: JBO made primary contributions to data collection and analysis, interpretation of results, and writing of the manuscript. GYHL helped to write the first draft. GYHL, MLH, PRH, GHG, and CT-P contributed to the study conception and design. All authors contributed to interpretation of results, all revised the manuscript critically for important intellectual content, and all approved the final manuscript. JBO is the guarantor.

  • Funding: None.

  • Competing interests: All authors have completed the Unified Competing Interest form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.

  • Ethical approval: No ethics approval is needed for retrospective register studies in Denmark. The study was approved by the Danish Data Protection Agency (No 2007-41-1667).

  • Data sharing: No additional data available.

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