Asthma Rates Post Puzzling Gain Among Children

Asthma rates in children and adolescents tripled in some groups over a 20-year period, according to a study that adds to evidence of a puzzling growth of the disease across the country.

There is no hard evidence for why rates rose from 1964 to 1983 in Rochester, Minn., study co-author Dr. Marc Silverstein said Thursday. But some researchers speculate that explanations could include more energy-efficient homes that can trap cat dander and other airborne particles, greater survival of low birth weight infants who may be prone to asthma, more cigarette smoking by mothers, and greater use of day care, which could expose more infants to viral infections that may promote asthma.

The approximate annual rate of new asthma cases tripled in boys and girls ages 10 to 14 and in girls ages 5 to 9. The rate doubled or nearly doubled in boys and girls ages 1 to 4 and in boys ages 5 to 9. No increases appeared in other age groups.

The report follows other studies that indicated asthma became more common in children during the 1970s and ‘80s, hospitalized more young children in the ‘80s and caused more deaths.

The federal Centers for Disease Control reported last week that the national asthma death rate rose 46% during the 1980s.

The work is presented in the October issue of the American Review of Respiratory Disease.

The study used medical records for 18,000 residents of Rochester, which is demographically similar to that of the national white population, researchers said.

The overall rate of new cases grew from 183 per 100,000 residents in 1964 to 284 per 100,000 in 1983. The change was due entirely to cases among children ages 1 to 14, researchers found.