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An independent and external validation of QRISK2 cardiovascular disease risk score: a prospective open cohort study

BMJ 2010; 340 doi: https://doi.org/10.1136/bmj.c2442 (Published 13 May 2010) Cite this as: BMJ 2010;340:c2442

Rapid Response:

Screening for future cardiovascular disease: the need for simplification

Screening for future
cardiovascular disease: the need for simplification

 

 

Collins and Altman[1] show that
QRISK1 or QRISK2 scores are more accurate in predicting future risk of cardiovascular
disease (CVD) than using the NICE Framingham
risk equations. For example, with the latter at a predicted 20% 10-year risk the
risk was actually about 15%. This difference is expected, because a person’s age
dominates in the prediction and the age-specific incidence of CVD events has
declined since the Framingham
risk equations were derived. The difference is of little importance in relation
to screening performance, because this depends on the ranking of risk estimates
separately in individuals who will and will not develop CVD over a given period;
an across-the-board reduction in absolute risk will not alter the ranking.  The screening performance based on using a 20%
10-year risk of CVD with QRISK and NICE Framingham
is given in the paper and summarized in the attached table. In women, because
the detection rate (sensitivity) happens to be the same (26%) it is possible to
assess the screening performance; using QRISK the false-positive rate was 6%,
for NICE Framingham
it was 7%, a 1 percentage point difference. Among men a direct comparison of
screening performance is not possible because neither the detection rate nor
the false-positive rate happen to be the same. Using the AUROC statistics given
in table 3 of their paper, the difference in the false-positive rates in men between
QRISK2 and NICE Framingham
for the same 26% detection rate is also 1%.

 

We think that the important issue
is not that someone is given a 20% 10-year risk of CVD instead of 15% (ie. about 2% a year instead of 1.5%), or that, for a given
detection rate, the difference in false-positive rates is only 1%. The issue is
that with the proposed QRISK2 screening strategy less than half of individuals
with CVD events are identified for preventive treatment, even though the
treatment (taking statins and blood pressure lowering
drugs) is effective, acceptably safe, and inexpensive. We suggest that more effort
needs to be spent on prevention and less on detailed screening assessments. Unless
the gain in screening performance for each additional component of the
screening algorithm is large in relation to the extra cost and complexity of
screening the additional component should not be recommended. This applies to the
elements in the Framingham
risk assessment as well as to QRISK1 and QRISK2.

 

It is perhaps time to review CVD
screening policy with the aim of specifying a simple, cost-effective method that
will lead to the prevention of most CVD events in the population with little
harm or inconvenience.

 

Nicholas J Wald*

Mark Simmonds

Wolfson Institute of Preventive
Medicine

Barts and the London School
of Medicine and Dentistry

Queen Mary University of London

Charterhouse Square

London
EC1M 6BQ

 

*Corresponding author: n.j.wald{at}qmul.ac.uk

 

 

1.                 
Collins GS, Altman DG. An independent and external
validation of QRISK2 cardiovascular disease risk score: a prospective open
cohort study. BMJ 2010:340:c2442

 

 

 

Table: Estimates of
detection rates, for CVD events and false-positive rate according to screening
algorithm and sex (from Collins and Altman[1]) using a 20% 10 year CVD risk
cut-off

 

Men

Women

Screening algorithm

Detection

rate

False-positive rate

Detection

rate

False-positive rate

QRISK2

40%

13%

26%

6%

NICE Framingham

54%

22%

26%

7%

 

Competing interests:
Nicholas Wald holds patents (granted and pending) on the formulation of a combined pill to simultaneously reduce four cardiovascular risk factors including blood pressure.

Competing interests: Collins and Altman[1] show thatQRISK1 or QRISK2 scores are more accurate in predicting future risk of cardiovasculardisease (CVD) than using the NICE

10 June 2010
Nicholas J Wald
Professor
Mark Simmonds
Wolfson Institute of Preventive Medicine, Queen Mary University of London