An analysis in 10 states of people hospitalized with the pandemic strain of H1N1 influenza shows that asthma is by far the most common underlying condition associated with severe cases of the disease. In children, other, much rarer chronic conditions, such as sickle cell anemia, cerebral palsy and muscular dystrophy, are also predisposing patients to life-threatening bouts of the virus, federal health officials said. Epidemiologists at the Centers for Disease Control and Prevention studied the experience of about 1,400 people older than 18 and 500 children who had been hospitalized in 10 states since the new influenza strain emerged in April. The states were California, Colorado, Connecticut, Georgia, Maryland, Minnesota, New Mexico, New York, Oregon and Tennessee. Among the hospitalized adults, 26 percent had asthma; 10 percent had diabetes; 8 percent had a chronic lung disease such as emphysema; 7.6 percent were immunosuppressed from cancer, HIV infection or another ailment; and 6.1 percent were pregnant. (Heart disease was also common, although CDC officials could not immediately say what fraction of patients had it.) In all, 45 percent of adults ill enough to be admitted to the hospital had a preexisting condition. CDC epidemiologists do not know what fraction of the rest were obese -- a newly recognized risk factor for severe or fatal flu. An earlier analysis of 227 patients found that 15 percent were obese and 8 percent were morbidly obese. Among children hospitalized with flu, asthma and neurological or muscular diseases were the most common underlying conditions, followed by blood disorders, especially sickle cell. About 6 percent of children had a blood disorder; percentages for the other conditions were not available.
