Nicole Bengiveno/The New York Times

Uninsured children who wind up in the hospital are much more likely to die than children covered by either private or government insurance plans, according to one of the first studies to assess the impact of insurance coverage on hospitalized children.

Researchers at Johns Hopkins Children’s Center analyzed data from more than 23 million children’s hospitalizations in 37 states from 1988 to 2005. Compared with insured children, uninsured children faced a 60 percent increased risk of dying, the researchers found.

The authors estimated that at least 1,000 hospitalized children died each year simply because they lacked insurance, accounting for 16,787 of some 38,649 children’s deaths nationwide during the period analyzed.

“If you take two kids from the same demographic background — the same race, same gender, same neighborhood income level and same number of co-morbidities or other illnesses — the kid without insurance is 60 percent more likely to die in the hospital than the kid in the bed right next to him or her who is insured,” said David C. Chang, co-director of the pediatric surgery outcomes group at the children’s center and an author of the study, which appeared today in The Journal of Public Health.

Although the research was not set up to identify why uninsured children were more likely to die, it found that they were more likely to gain access to care through the emergency room, suggesting they might have more advanced disease by the time they were hospitalized.

In addition, uninsured children were in the hospital, on average, for less than a day when they died, compared with a full day for insured children. Children without insurance incurred lower hospital charges — $8,058 on average, compared with $20,951 for insured children.

In children who survived hospitalization, the length of stay and charges did not vary with insurance status.

The paper’s lead author, Dr. Fizan Abdullah, assistant professor of surgery at Johns Hopkins, dismissed the possibility that providers gave less care or denied procedures to the uninsured. “The children who were uninsured literally died before the hospital could provide them more care,” Dr. Abdullah said.

Furthermore, Dr. Abdullah said, indications are that the uninsured children “are further along in their course of illness.”

The results are all the more striking because children’s deaths are so rare that they could be examined only by a very large study, said Dr. Peter J. Pronovost, a professor of surgery at Johns Hopkins and an author of the new study.

“The striking thing is that children don’t often die,” Dr. Pronovost said. “This study provides further evidence that the need to insure everyone is a moral issue, not just an economic one.”

An estimated seven million children are uninsured in the United States, despite recent efforts to extend coverage under the federal Children’s Health Insurance Program.

Advocates for children said they were saddened by the findings but not surprised.

“We know from studies of adults that lack of insurance contributes to worse outcomes, and this study provides evidence that there are similar consequences for children,” said Alison Buist, director of child health at the Children’s Defense Fund, a nonprofit advocacy organization. “If you wait until a child gets care at a hospital, you have missed an opportunity to get them the types of screening and preventive services that prevent them from getting to that level of severity to begin with.”

The most common reasons for children being hospitalized were complications from birth, pneumonia and asthma. The study found that the reasons did not differ depending on insurance status.

Earlier studies have found that uninsured children are more likely than insured children to have unmet medical needs, like untreated asthma or diabetes, and are more likely to go for two years without seeing a doctor.

Following a recent expansion, 14 million children will be covered by the CHIP program by 2013, according to the Congressional Budget Office. Advocates for children are concerned that efforts to overhaul the health care system may actually reverse the progress made toward covering more children if CHIP is phased out and many families remain unable to afford health insurance.

“You can’t just dump 14 million vulnerable children into a new system without evidence that the benefits and the affordability provisions are better than they are now,” Dr. Buist said. “That’s not health reform.”