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An independent external validation and evaluation of QRISK cardiovascular risk prediction: a prospective open cohort study

BMJ 2009; 339 doi: https://doi.org/10.1136/bmj.b2584 (Published 07 July 2009) Cite this as: BMJ 2009;339:b2584
  1. Gary S Collins, medical statistician1,
  2. Douglas G Altman, professor of statistics in medicine1
  1. 1Centre for Statistics in Medicine, Wolfson College Annexe, University of Oxford, Oxford OX2 6UD
  1. Correspondence to: G S Collins gary.collins{at}csm.ox.ac.uk
  • Accepted 28 April 2009

Abstract

Objective To independently evaluate the performance of the QRISK score for predicting 10 year risk of cardiovascular disease in an independent UK cohort of patients from general practice and compare the performance with Framingham equations.

Design Prospective open cohort study.

Setting 274 practices from England and Wales contributing to the THIN database.

Participants 1.07 million patients, registered between 1 January 1995 and 1 April 2006, aged 35-74 years (5.4 million person years) with 43 990 cardiovascular events.

Main outcome measures First diagnosis of cardiovascular disease (myocardial infarction, coronary heart disease, stroke, and transient ischaemic attack) recorded in general practice records.

Results This independent validation indicated that QRISK offers an improved performance in predicting the 10 year risk of cardiovascular disease in a large cohort of UK patients over the Anderson Framingham equation. Discrimination and calibration statistics were better with QRISK. QRISK explained 32% of the variation in men and 37% in women, compared with 27% and 31% respectively for Anderson Framingham. QRISK underpredicted risk by 13% for men and 10% for women, whereas Anderson Framingham overpredicted risk by 32% for men and 10% for women. In total, 85 010 (8%) of patients would be reclassified from high risk (≥20%) with Anderson Framingham to low risk with QRISK, with an observed 10 year cardiovascular disease risk of 17.5% (95% confidence interval 16.9% to 18.1%) for men and 16.8% (15.7% to 18.0%) for women. The incidence rate of cardiovascular disease events among men was 30.5 per 1000 person years (95% confidence interval 29.9 to 31.2) in high risk patients identified with QRISK and 23.7 per 1000 person years (23.2 to 24.1) in high risk patients identified with Anderson Framingham. Similarly, the incidence rate of cardiovascular disease events among women was 26.7 per 1000 person years (25.8 to 27.7) in high risk patients identified with QRISK compared with 22.2 per 1000 person years (21.4 to 23.0) in high risk patients identified with Anderson Framingham.

Conclusions The QRISK cardiovascular disease risk equation offers an improvement over the long established Anderson Framingham equation in terms of identifying a high risk population for cardiovascular disease in the United Kingdom. QRISK underestimates 10 year cardiovascular disease risk, but the magnitude of underprediction is smaller than the overprediction with Anderson Framingham.

Footnotes

  • Contributors: GSC conducted the analysis and prepared the first draft, which was revised according to comments and suggestions from DGA. GSC is guarantor for the paper.

  • Funding: This study was commissioned by the Department of Health. The funder had no role in the study design, analysis, or interpretation or writing of the manuscript.

  • Competing interests: None declared.

  • Ethnical approval: Not required.

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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