Prothrombotic changes in hemostatic parameters and C-reactive protein in the elderly with winter acute respiratory tract infections

Mortality rates attributable to cerebrovascular and ischemic heart disease increase among older adults during the winter. Prothrombotic changes in the hemostatic system related to seasonal factors, such as ambient temperature changes, and winter acute respiratory tract infections, may contribute to this excess seasonal mortality, A prospective nested case-control study was conducted to assess the impact of winter acute respiratory tract infection s on fibrinogen. factor VII, factor VIIa, D-dimer, prothrombin fragment 1.2 , PAI-1, soluble P-selectin and C-reactive protein (CRP) in older adults. T he change in laboratory parameters from baseline (fall) to the time of infe ction in both middle-aged and elderly individuals was compared with matched non-infected controls. in older adult participants with winter acute respi ratory tract infections, significant increases occurred in fibrinogen and C -reactive protein, but not in any other markers. The mean fibrinogen increa sed 1.52 gn. (38%) and the mean CRP increased 37 mg/L (370%) over baseline (both p <0.001). In a multivariate analysis, both infection and season were associated with the increase in fibrinogen, but only infection was associa ted with the CRP increase. Old age magnified the increase in CRP but not in fibrinogen. Winter acute respiratory tract infections induce an exaggerate d inflammatory response in older adults. The associated increase in fibrino gen, an independent risk factor far ischemic heart disease, may be partly r esponsible for the excess winter vascular mortality.