Mendelian Randomization Suggests No Causal Association Between C-reactive Protein and Carotid Intima-media Thickness in the Young Finns Study

Abstract

To the Editor: It is unclear whether C-reactive protein (CRP), a nonspecific marker of acute phase inflammatory response, is causally related to arterial intima-media thickness (IMT), a risk factor for coronary heart disease (CHD). Previous evidence from conventional observational studies is inconsistent and suggests that the association may be biased or confounded.1 According to the Mendelian randomization approach, the genetic variants in the CRP gene ( CRP ) may represent good instruments for CRP levels that are largely free from reverse causation bias and confounding.1 If the association between CRP and IMT is causal, then genetic variants in CRP should be related to IMT to the extent predicted by the magnitude of their association with average CRP levels. …