Oﬃce for National Statistics. Population estimates by ethnic group. http://www.ons. gov.uk/ons/taxonomy/index.html?nscl= Population+Estimates+by+Ethnic+Group#tabdata-tables (accessed Dec 23, 2013). Ahmed SF, Franey C, McDevitt H, et al. Recent trends and clinical features of childhood vitamin D deﬁciency presenting to a children’s hospital in Glasgow. Arch Dis Child 2011; 96: 694–96.
Reﬁning the American guidelines for prevention of cardiovascular disease We would like to propose a compromise in the debate on the clinical application of the recently proposed American guidelines for prevention of cardiovascular disease.1 Paul Ridker and Nancy Cook (Nov 30, p 1762)2 criticise the current guidelines’ assumption of a constant relative risk reduction and its subsequent focus on absolute (baseline) risk predictions. They plea for statins prescription based on treatment eﬀects observed in specific trial populations. In our view, combining absolute risk predictions with individualised estimates of relative risk reduction is required to quantify the absolute treatment beneﬁt of statins. Relative risk reduction across subgroups with diﬀerent levels of baseline risk can be based on the results of the individual patient data meta-analysis of statin trials. 3 Ideally, the individualised relative risk reductions are estimated in a re-analysis of these trial data, by adding a statistical treatment interaction with the risk predictions according to 2013 guidelines.4 Ridker and Cook recommend recalibration of the guidelines’ new prediction model in additional external validation cohorts. Rather, we should use already available contemporary validation cohorts to adjust poorly calibrated risk predictions for time trends. To account for well recognised cardiovascular disease risk diﬀerences across the ethnic groups of Hispanics, Asians, and native-Americans, 598
recalibration might be based on available external data as well.5 In conclusion, we recommend building guidelines on adequate estimates of absolute treatment benefit, requiring a recalibrated absolute risk prediction model in conjunction with individualised estimates of the relative risk reduction. We declare that we have no conﬂicts of interest.
*David van Klaveren, Yvonne Vergouwe, Ewout W Steyerberg [email protected]
Department of Public Health, Erasmus MC, 3015 Rotterdam, The Netherlands 1
Stone NJ, Robinson J, Lichtenstein AH, et al. 2013 ACC/AHA guideline on the treatment of blood cholesterol to reduce atherosclerotic cardiovascular risk in adults: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation 2013; published online Nov 13. DOI:10.1161/01.cir.0000437738.63853.7a. Ridker PM, Cook NR. Statins: new American guidelines for prevention of cardiovascular disease. Lancet 2013; 382: 1762–65. Cholesterol Treatment Trialists’ (CTT) Collaborators. The eﬀects of lowering LDL cholesterol with statin therapy in people at low risk of vascular disease: meta-analysis of individual data from 27 randomised trials. Lancet 2012; 380: 581–90. Kent DM, Rothwell PM, Ioannidis JP, Altman DG, Hayward RA. Assessing and reporting heterogeneity in treatment eﬀects in clinical trials: a proposal. Trials 2010; 11: 85. D’Agostino RB Sr, Grundy S, Sullivan LM, Wilson P, Group CHDRP. Validation of the Framingham coronary heart disease prediction scores: results of a multiple ethnic groups investigation. JAMA 2001; 286: 180–87.
The recent American Heart Association (AHA) and American College of Cardiology (ACC) guidelines1 recommend that more people are offered treatment to prevent heart attacks and strokes; they do this by lowering the risk cutoff from a 20% 10-year risk to 7·5% (the approximate risk of a person aged 60 years). Paul Ridker and Nancy Cook state that the risk calculator in the guidelines overestimates risk about two-fold.2 This variation, however, has little eﬀect on discriminating between who will and will not have a heart attack or stroke (ie, on screening performance).3 Age has a much greater discriminatory effect than do risk factors such as
blood pressure and cholesterol despite their aetiological importance.3 Screening using age alone has advantages. It is simple and removes the need for risk estimation, which is only necessary when many screening factors are combined (eg, in antenatal screening for Down’s syndrome, where no single marker dominates over others). Therefore, screening using age alone avoids debate about the accuracy of risk estimation using different algorithms, none of which materially improve screening performance over age alone.4 Also, the focus should move from risk in the absence of intervention to the health beneﬁt of intervention, which is what matters. If people took blood pressure and cholesterol lowering medicines from age 60 years without previous risk factor measurement, one third would beneﬁt and they would, on average, gain 7 years of life without a heart attack or stroke. NW jointly holds European, Canadian, and US patents for a combinaton pill for the prevention of cardiovascular disease. JM declares that he has no conﬂicts of interest.
*Nicholas Wald, Joan Morris [email protected]
Wolfson Institute of Preventive Medicine, London, EC1M 6BQ, UK 1
Stone NJ, Robinson J, Lichtenstein AH, et al. 2013 ACC/AHA guideline on the treatment of blood cholesterol to reduce atherosclerotic cardiovascular risk in adults: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol 2013; published online Nov 13. DOI:10.1016/j. jacc.2013.11.002. Ridker PM, Cook NR. Statins: new American guidelines for prevention of cardiovascular disease. Lancet 2013; 382: 1762–65. Wald NJ, Simmonds M, Morris JK. Screening for future cardiovascular disease using age alone compared with multiple risk factors and age. PLoS One 2011; 6: e18742. Simmonds MC, Wald NJ. Risk estimation versus screening performance: a comparison of six risk algorithms for cardiovascular disease. J Med Screen 2012; 19: 201–05.
Paul Ridker and Nancy Cook1 express concern that the new American Heart Association (AHA) and American College of Cardiology (ACC) risk calculator “systematically overestimates” observed risks.2 This www.thelancet.com Vol 383 February 15, 2014