Finding a needle in a haystack is a proverbially difficult task. The chance of finding a needle is increased if the haystack is made up of a substantial proportion of needles, unless the needles are identical in appearance to the hay. This illustrates a challenge in the development of risk prediction models for cardiovascular disease (CVD) events in rheumatoid arthritis (RA). Although there are many needles in the RA population (i.e., individuals with elevated CVD risk appropriate for early preventive intervention), many do not appear to be high risk based on traditional CVD risk factors. As a telling illustration, Crowson, et al1 demonstrated that 16% of the 525 patients with RA from Olmsted County, Minnesota, USA, experienced a CVD event during 10 years of followup. However, the 10-year Framingham risk score only predicted that 8.7% would have an event, a striking difference that illustrates the potential contribution of nontraditional risk factors, such as those related to RA disease activity and severity, to CVD risk.
When almost 50% of the needles look like hay, how do you separate them? An early approach proposed was to multiply an individual’s CVD risk score by 1.5, based on the oft-cited average relative increase in CVD events for RA compared with the general population2,3. Although based on expert opinion and not validated using data from a longitudinal cohort, this strategy was recommended by a guideline committee organized by the European League Against Rheumatism Standing Committee for Clinical Affairs. In its first guideline published in 20104, the committee recommended using the 1.5 multiplication of the CVD risk score …
Address correspondence to Dr. J.T. Giles. E-mail: jtg2122{at}columbia.edu