More than a quarter of American children have a chronic health condition such as obesity or asthma, but many children overcome these problems with time, U.S. researchers said.
They said the findings make clear that chronic health conditions are rising among children, and access to healthcare is essential to diagnose and treat them.
"A lot of kids will have chronic conditions over the course of their childhood," said Dr. Jeanne Van Cleave of Massachusetts General Hospital for Children in Boston, who worked on the study published in the Journal of the American Medical Association.
"It is very important for children to have continuous access to high-quality healthcare, especially primary care, where a lot of these conditions are picked up and treated," she said in a telephone interview.
Van Cleave and colleagues used data from a government survey of three groups of children — each group with about 1,000 or more children — aged 2 through 8 between 1988 and 2006.
They found the rate of chronic health conditions — obesity, asthma and learning problems such as attention deficit hyperactivity disorder or ADHD — doubled to 26.6 percent in 2006 from 12.8 percent in 1994.
"The good news is, for about half of these kids, their conditions will go away over time," Van Cleave said.
They found that 16.6 percent of all the children surveyed had a chronic condition at the beginning of the study period, and 20.8 percent reported having a chronic condition at the end.
But only 7.4 percent of the children had a chronic condition both at the beginning and at the end of the study period, and 9.3 percent of children reported having a chronic condition at the beginning of the study that was not present at the end.
"It's a very hopeful finding. It offers a lot of opportunity for prevention and for finding out more about why certain chronic conditions resolve, and why others don't, and why the same chronic condition in one child will resolve and why it doesn't in another child," Van Cleave said.
The trick, she said, is finding out why conditions go away so that more children may be helped.
She said future studies need to look at what factors surround the kids who see improvements compared with the ones who do not.
"Our study didn't specifically look at for which children the chronic condition of obesity was less likely to resolve. That would be a very important piece of information we could use in actual medical care," Van Cleave said.
Dr. Geetha Raghuveer of Children's Mercy Hospital in Kansas City, Missouri, who was not involved with the study, said that while it was heartening that chronic conditions went away in several children, it was worrying that such a large percentage of children had a chronic health problem at some point.
She said these problems "will need prevention strategies geared toward larger environments such as families, schools, communities," and laws that make nutritious foods more accessible and affordable.