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

doi:10.1136/bmj.b2584

Published 7 July 2009, doi:10.1136/bmj.b2584
Cite this as: BMJ 2009;339:b2584

Research

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

Gary S Collins, medical statistician¹, Douglas G Altman, professor of statistics in medicine¹

¹ Centre for Statistics in Medicine, Wolfson College Annexe, University of Oxford, Oxford OX2 6UD

Correspondence to: G S Collins gary.collins{at}csm.ox.ac.uk

Objective To independently evaluate the performance of the QRISKscore for predicting 10 year risk of cardiovascular diseasein an independent UK cohort of patients from general practiceand compare the performance with Framingham equations.

Design Prospective open cohort study.

Setting 274 practices from England and Wales contributing tothe THIN database.

Participants 1.07 million patients, registered between 1 January1995 and 1 April 2006, aged 35-74 years (5.4 million personyears) with 43 990 cardiovascular events.

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

Results This independent validation indicated that QRISK offersan improved performance in predicting the 10 year risk of cardiovasculardisease in a large cohort of UK patients over the Anderson Framinghamequation. Discrimination and calibration statistics were betterwith QRISK. QRISK explained 32% of the variation in men and37% in women, compared with 27% and 31% respectively for AndersonFramingham. QRISK underpredicted risk by 13% for men and 10%for women, whereas Anderson Framingham overpredicted risk by32% for men and 10% for women. In total, 85 010 (8%) of patientswould be reclassified from high risk ( $≥$ 20%) with Anderson Framinghamto low risk with QRISK, with an observed 10 year cardiovasculardisease 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 incidencerate of cardiovascular disease events among men was 30.5 per1000 person years (95% confidence interval 29.9 to 31.2) inhigh risk patients identified with QRISK and 23.7 per 1000 personyears (23.2 to 24.1) in high risk patients identified with AndersonFramingham. Similarly, the incidence rate of cardiovasculardisease events among women was 26.7 per 1000 person years (25.8to 27.7) in high risk patients identified with QRISK comparedwith 22.2 per 1000 person years (21.4 to 23.0) in high riskpatients identified with Anderson Framingham.

Conclusions The QRISK cardiovascular disease risk equation offersan improvement over the long established Anderson Framinghamequation in terms of identifying a high risk population forcardiovascular disease in the United Kingdom. QRISK underestimates10 year cardiovascular disease risk, but the magnitude of underpredictionis smaller than the overprediction with Anderson Framingham.

© Collins et al 2009
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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Tunstall-Pedoe, H., Woodward, M., Watt, G. (2009). ASSIGN, QRISK, and validation. BMJ 339: b3514-b3514 [Full text]
Collins, G. S, Altman, D. G (2009). Authors' reply. BMJ 339: b3516-b3516 [Full text]
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