Many low-income American families with sick children are being enrolled in high-deductible health-care plans, a new study has found.

In 2007, about 10 percent of employers offered high-deductible plans, and about 14.8 million adults were enrolled in the plans. But as more families with sick children are enrolled in these plans, there are concerns that families facing high out-of-pocket costs might fail to get recommended care for their children, according to background information in a news release on the study from Children's Hospital Boston.

About half of the people enrolled in high-deductible plans in 2007 did not have a choice of plans, according to a national survey that year.

In this study, researchers analyzed enrollment and claims data from Harvard Pilgrim Health Care in New England. They identified 839 families with children who initially had traditional HMO (health maintenance organization) plans through Harvard Pilgrim but whose employers switched them to a high-deductible health plan when Harvard Pilgrim began offering it. The researchers compared these families with 5,133 families whose employers stayed with the traditional plan.

About one-third of the families who were switched to a high-deductible plan had a child with a chronic condition, 13 percent lived in neighborhoods with high poverty, 36 percent had an above-average burden of illness, and 19 percent had incurred more than $7,000 a year in health-care costs, including out-of-pocket costs.

The study also found:

* Among families who got their insurance through large employers, those living in high-poverty neighborhoods were 1.78 times more likely than families in higher-income areas to be switched to a high-deductible plan.

* Families with coverage through a small employer were less likely to be switched to a high-deductible plan if they had more children, an above-average burden of illness and higher health-care expenditures. Those who were switched tended to be healthier and have fewer children.

The study was published in the April issue of the journal Pediatrics.

"The usual assumption is that high-deductible plans attract healthy and wealthy people, based on studies of people who chose those plans themselves," Dr. Alison Galbraith, of Children's Hospital Boston and Harvard Medical School and an author of the study, said in the news release.

"Our population only had one plan offered to them, and we found that many of those who were switched to high-deductible plans had children with chronic conditions," Galbraith said. "There wasn't a difference in the amount of chronic illness between the high-deductible and traditional families, but it was striking that there wasn't less illness in the high deductible group. We need to be aware of this as these plans become more popular."

The findings "show that families with children in high-deductible plans may comprise two distinct groups, one with higher-risk characteristics and one with lower-risk characteristics compared to traditional plans," she said. "This makes it important to monitor the effects of enrollment in high-deductible plans on children's use of needed care, especially for vulnerable populations that are enrolled."