Inflammatory cytokines such as IL-1 and TNF alpha are postulated to play a role in development of anemia of chronic disease through inhibition of erythropoietin synthesis.[20] It is known that the elderly have increased levels of inflammatory cytokines, but it is unclear whether this is the result of the cardiovascular effects associated with aging or of the aging process itself.[21] Inflammatory markers such as C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) were collected as part of the study, but only a minority of patients underwent these tests. Here, EPO is linked to anemia (phenotype).