The risks in risk prediction

Comprehensive assessment of the risk of cardiovascular disease using a multiple risk factor system is now widely accepted as the method of choice for targeting interventions in primary prevention. However, several risk equations are available, and there is no consensus on which system or score to use.1 In the linked paper (doi:10.1136/bmj.e4181),2 a risk estimation system (QRISK2-2011), which was derived from the UK QRESEARCH database, is examined in an independent UK population to assess its predictive ability. Such external validation studies are necessary in the development of risk estimation systems to prove the accuracy and generalisability of such systems.

This important study shows that QRISK2-2011 has both better callibration (the degree to which the number of events predicted by the risk estimation system agree with the number of events observed) and better discrimination (a measure of how correctly the system ranks risk between individuals) than the National Institute for Health and Clinical Excellence (NICE) version of the Framingham equation. The NICE Framingham equation is based on the 1991 Anderson Framingham equation, which is known to overpredict disease levels in some populations.1 3 Comparisons of …