Response of C-reactive protein and serum amyloid a to influenza A infection in older adults

Influenza epidemics are associated with significant morbidity and mortality in the elderly, with a substantial proportion of deaths due to cardiovascu lar events. Elevations of acute-phase proteins have been associated with an increased risk of atherosclerotic events. Therefore, serum amyloid A (SAA) and C-reactive protein (CRP) were measured during influenza illness and 4 weeks later in 7 young persons, 15 elderly outpatients, and 36 hospitalized adults. Striking elevations were seen in mean acute SAA and CRP levels in all groups, but hospitalized patients had the highest levels (SAA, 503 vs. 310 mug/mL [P = .006]; CRP, 120 vs. 34 mug/mL [P < .001]). The presence of dyspnea, wheezing, and fever was also associated with high CRP levels. Infl uenza infection is associated with significant elevations of SAA and CRP le vels in elderly patients, especially those who require hospitalization. It is possible that direct effects of CRP may exacerbate preexisting atheroscl erotic lesions and may help explain cardiovascular events associated with a cute influenza.