More than 14 million—or 22.7 percent—of U.S. children were underinsured in 2007, says a study published late last month in the New England Journal of Medicine.

That was far higher than the 3.4 million children found to be without insurance at all during the year and the 7.6 million children who had insurance during only part of the year, the data showed.

The study, titled Underinsurance Among Children in the United States, was conducted by researchers at the Health Resources and Services Administration (HRSA). It drew data from the 2007 National Survey of Children's Health, a nationally-representative study that looked at more than 91,000 children and examined underinsurance, or insurance that does not sufficiently meet a child's needs.Researchers looked at children who were never insured in the previous year, children who were insured only part of the year, and children who had health insurance throughout the year.

"Much has been written about expanding health insurance coverage for children," says lead author Dr. Michael D. Kogan, a researcher in HRSA's Maternal and Child Health Bureau. "Far less attention has been devoted to whether insurance sufficiently meets children's needs."

The study asked parents three key questions: whether parents thought that their child's health insurance offered benefits or covered services that met his or her needs; whether the child's health insurance allowed them to see needed providers; and whether out-of-pocket costs were reasonable. The child was considered underinsured if the parent did not answer "usually" or "always" to all three questions, even if they were insured throughout the year.

Other study findings include the following:

•Older children, black and Hispanic children, children in fair or poor health, and children with special health-care needs were more likely to be underinsured.

•Children with private insurance were more likely to be underinsured than those with public insurance (24.2 percent versus 14.7 percent).

•The most common reason for underinsurance was that costs paid by the family weren't viewed as reasonable.

•Publicly insured children were more likely to report difficulties seeing needed providers, whereas parents of privately insured children were much more likely to report having inadequate coverage of charges.

•Underinsured children have problems with access to health care similar to those of uninsured children.

•Compared to children who were consistently and adequately insured throughout the year, underinsured children were more likelyto have difficulty obtaining referrals for needed care, lacked a usual source of care, delayed or didn't get needed care, and had problems getting care from specialists when needed.

HRSA, a part of the U. S. Department of Health and Human Services, is the primary federal agency for improving access to health-care services for people who are uninsured, isolated, or medically vulnerable.