Lung disease was the most common underlying condition in a British study of 192 patients who had been admitted to the hospital because of complications related to H1N1 influenza.1 More than 25% of those hospitalized had asthma.
The second most common comorbidity was cardiac disease (15% of patients), and pregnant women accounted for 5% of those hospitalized.
Many of the younger patients in the study had been previously healthy. About half of the 80 patients age 16 to 44 years and 35 of the 40 children younger than 5 years with H1N1-related complications had no known comorbidities.
1. Ellis O. People with asthma are most at risk of complications from swine flu, study shows. BMJ. 2009;339:b4103.