Survey of underlying conditions of persons hospitalized with acute respiratory disease during influenza epidemics in Houston, 1978-1981.

The peak occurrence of hospitalizations of persons with acute respiratory disease (ARD), usually pneumonia, has coincided with the peak of influenza virus activity each year. The purpose of this study was to examine the diagnoses other than ARD on the discharge record of patients hospitalized with ARD. We were particularly interested in determining the frequency of high-risk conditions for which influenza vaccine is currently recommended. The risk for ARD hospitalization was 19.7 per ten thousand for persons with high-risk conditions and only 9.3 for persons without. Chronic pulmonary disorders were the most common underlying conditions identified, and persons with pulmonary conditions had the greatest risk for ARD hospitalization. The highest rate occurred among persons older than 65 yr of age with pulmonary conditions (87.5 per ten thousand), and the rate was 27.5 for persons 45 to 64 yr of age. Cardiac conditions were the second most frequent group of underlying disorders of patients hospitalized with ARD. Only for persons younger than 20 yr of age was the risk of ARD hospitalization greater for persons with cardiac conditions than for those with pulmonary conditions (22.9 and 14.9 per ten thousand, respectively). Death, however, was more frequent among persons with underlying heart disease. Intensified effort is needed to fully implement recommendations for prophylaxis of influenza in order to reduce these risks.