Interleukin-6 and incident coronary heart disease: Results from the British Women's Heart and Health Study

IntroductionInflammatory mechanisms may play a role in the pathogenesis of atherosclerosis and its complications. Interleukin-6 (IL-6) is an ‘upstream’ pro-inflammatory cytokine that stimulates hepatocytes to synthesize acute phase response proteins such as C-reactive protein (CRP) and fibrinogen. The purpose of this study was to determine whether IL-6 is associated with incident coronary heart disease (CHD) events independently of established risk factors and to examine its predictive ability for future CHD events.MethodsData from the British Women's Heart and Health Study, a prospective cohort of randomly sampled British women 60–79 years old at baseline was used. Three thousand five hundred and eighty-one women had no evidence of coronary heart disease at baseline and were followed up for a median of 4.6 years. Cox proportional hazard models were used to estimate the association of IL-6 with incident CHD.ResultsThe age-adjusted association of IL-6 with the risk of CHD (hazard ratio, HR per doubling of IL-6 = 1.26, 95% CI 1.10, 1.43) was attenuated when adjusting for established CHD risk factors (HR per doubling of IL-6 = 1.13, 95% CI 0.97, 1.31). The main confounders of the association of IL-6 and CHD risk were smoking and forced expiratory volume (FEV1). Further attenuation was observed when additional terms for components of the metabolic syndrome were added into the model (HR = 1.08, 95% CI 0.93, 1.27).ConclusionsThere was no strong evidence of an association between IL-6 and incident CHD in older British women after controlling for established CHD risk factors. Studies with measures of lung function and socio-economic position are needed to further investigate the role of IL-6 in CHD etiology.