WEDNESDAY, Aug. 11 (HealthDay News) -- White children and those in poor families are more likely to have repeated ear infections than other children, U.S. researchers have found.

Ear infection (also called otitis media) is one of the most common health problems in children. By the age of 3, more than 80 percent of children have had at least one ear infection. The cost of medical and surgical treatment of these infections is $3 billion to $5 billion a year in the United States.

About 4.65 million U.S. children suffer frequent ear infections each year, defined as more than three infections over 12 months, according to background information in the study by University of California, Los Angeles (UCLA) and Harvard University researchers.

The research team analyzed 1997-2006 data from the U.S. National Health Interview Survey and found that the rates of frequent ear infections were 7 percent for white children, 6.2 percent for Hispanic children, 5 percent for black children, and 4.5 percent for children of other racial or ethnic groups. The average age of the children in the study was 8.5 years.

The study authors also found that the rate of frequent ear infections among children in households below the poverty line was higher (8 percent) than that for those in families above the poverty line.

"The racial and ethnic disparity was somewhat surprising," study co-author Dr. Nina Shapiro, director of pediatric otolaryngology at Mattel Children's Hospital UCLA, said in a UCLA news release.

"We are not certain why these gaps exist, but possible explanations could include anatomic differences, cultural factors or disparate access to health care. It could also be that white children are overdiagnosed and non-white children are underdiagnosed," she said.

The findings are published in the August issue of the journal Laryngoscope.

More information

The Nemours Foundation has more about ear infections in children.