As part of the Women Health Initiative (WHI) Study, researchers wished to investigate the role of systemic inflammation in predicting cardiovascular disease in women (N Engl J Med 2002;347(20):1557-65). Researchers used a prospective study design with a large sample size. Blood levels of C-reactive protein (CRP) were measured at baseline and women were followed for an average of 8 years. The following Table shows the relative risk estimates of a cardiovascular event (heart attack or stroke) within 5 years by quintile of CRP level for the 30,000 women. The first quintile is used as the reference category. Based on the relative risk data below, one can conclude: (note: quintile means any of five equal groups into which a population can be divided according to the distribution of values of a particular variable.) Quintile of CRP Level 2 0.49 50.40- 1.08 >1.08-2.09 >2.09-4.10 24.10 mo/dL mo dl mo/dl moldL ma/dL Relative Risk 1.0 Number of Women 8000 O There is no risk of heart attack/stroke for women with CRP levels in the first quintile. Decreasing CRP level appears to increase the risk of heart attack/stroke, Increasing CRP level appears to increase the risk of heart attack/stroke. There appears to be no association between CRP levels and heart attack/stroke