Pulmonary complications of interpandemic influenza A in hospitalized adults.
BACKGROUND
To define the pulmonary complications of influenza during the current interpandemic period, we reviewed clinical, laboratory, and radiographic data from 193 adults (> or =18 years old) (1999-2003) who were hospitalized with influenza A during 4 winters.


RESULTS
The mean age was 75 years, 8% had documented bacterial infection, 15% required intensive care unit treatment, and 6% died. Chest radiograph (CXR) findings were classified as showing acute disease (AD; n=101) or no AD (NAD; n=92). Most CXR findings were subtle in nature. Subjects with AD were more likely to have > or =1 cardiac diagnosis (odds ratio [OR], 2.2 [95% confidence interval {CI}, 1.2-4.1]), to have rales on examination (OR, 1.9 [95% CI, 1.0-3.7]), to be symptomatic for >3 days (OR, 2.2 [95% CI, 1.2-4.1]), and to be less likely to wheeze (OR, 0.37 [95% CI, 0.20-0.70]). Total and neutralizing anti-influenza antibody titers were lower in patients with influenza than in respiratory syncytial virus-infected control subjects (P<.05), which suggests a protective effect of antibody. Interestingly, antibody titers did not differ between subjects with AD and those with NAD.


CONCLUSIONS
In the absence of significant antigenic shifts, previous exposure to influenza, including vaccinations, may play a role in reducing the severity of influenza-associated lower respiratory tract disease.
Murata
Yoshihiko
Y
Department of Medicine, University of Rochester School of Medicine and Dentistry and Infectious Diseases Unit, Department of Medicine, Rochester General Hospital, Rochester, NY 14621, USA. Yoshihiko.Murata@viahealth.org
Walsh
Edward E
EE
Falsey
Ann R
AR
D000293:Adolescent; D000328:Adult; D000368:Aged; D000956:Antigens, Viral / Q000097:blood; D004196:Disease Outbreaks; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D009980:Influenza A virus / Q000235:genetics / Q000276:immunology; D007251:Influenza, Human / Q000150:complications*; D008297:Male; D008875:Middle Aged; D009518:New York / Q000453:epidemiology; D011859:Radiography; D012141:Respiratory Tract Infections / Q000097:blood / Q000150:complications / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000473:pathology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012720:Severity of Illness Index; D013183:Sputum / Q000821:virology
D000956:Antigens, Viral; D007074:Immunoglobulin G