Asthma Differs in Rich, Poor Countries

The link between childhood asthma and allergies may be twice as strong in rich nations compared with poorer countries.

That's according to a new study from researchers including Gudrun Weinmayr, PhD, of Germany's Ulm University.

They gathered data on more than 54,000 children aged 8-12 in 22 countries worldwide, including study centers in the U.K., Ghana, India, Brazil, China, Sweden, and Ecuador.

Some of the kids lived in big cities. Others lived in rural areas. Their parents reported the children's asthma symptoms. More than half of the kids also got allergy skin tests.

Asthma symptoms, such as wheeze, varied widely among the countries, ranging from less than 1% in Pichincha, Ecuador, to more than a quarter in Uruguaiana, Brazil.

The researchers checked the countries' gross national income and found a wealth gap in the asthma data.

Overall, in wealthier countries, kids with asthma were twice as likely to test positive for allergies as those in less affluent nations.

The numbers varied a lot from nation to nation. Near the extremes are Mumbai, India, where only 2% of kids with tested positive for allergies, compared with nearly 59% in the Netherlands.

The reasons for that pattern aren't clear. The researchers didn't have details about all the factors that could make a child more or less likely to develop asthma and allergies.

But nutrition, pollution, housing conditions, exposure to microbes, and other factors may play a role, Weinmayr's team suggests.

The findings only apply on a global scale. So don't make assumptions about links between personal wealth and children's allergies and asthma, the researchers warn.