As members of the Obama administration and Congress met on Thursday to try to find common ground on health care, a new report warned that without comprehensive legislation, more than 275,000 adults nationwide will die over the next decade because of a lack of health insurance. Nearly 14,000 of those deaths would occur in New York State.

An earlier study by the Institute of Medicine estimated that 18,000 people died prematurely in 2000 because they lacked insurance; the Urban Institute updated that figure to 22,000 in 2006. The new study, by liberal advocacy group Families USA, applied the same methodology used in the previous reports to drill down and calculate, on both a national and state-by-state basis, the latest figures.

“This is only the tip of the iceberg, and the most severe consequence, which is death,” said Kathleen Stoll, director of health policy at Families USA. In addition, thousands of other citizens, perhaps millions, are experiencing a reduction in the quality of their lives and their health because they lack insurance, she said.

Not surprisingly, many of the states with the largest number of projected premature deaths also have the largest populations. The top 12 states, in order of estimated premature deaths, are: California (34,600), Texas (31,700), Florida (25,400), New York (13,900), Georgia (11,500), North Carolina (9,600), Illinois (9,400), Ohio (8,900), Louisiana (7,700), Michigan (7,600), Pennsylvania (7,500) and Tennessee (7,500).

In 2008, roughly 46 million people in the United States lacked health insurance, according to the Census Bureau. The new report estimates that currently 68 adults under age 65 die every day because they don’t have coverage. Absent a significant change in coverage, the figure will climb to 84 by 2019, the study projects.

A growing body of research has explored the connection between a lack of health insurance and an increased risk of death. Uninsured people are more likely to skip screenings and other preventive care, so their medical problems are often diagnosed later, when they are more advanced and tougher to treat. The uninsured are also more likely to skimp on necessary medical care, whether it’s prescription drugs to keep their blood pressure in check or surgery to clear up clogged arteries.

“The bottom line is that if you don’t get a disease picked up early and you don’t get necessary treatment, you’re more likely to die,” said Stan Dorn, a senior fellow at the Urban Institute and the author of the organization’s earlier study.

Experts say that the new study’s estimates of premature death likely err on the conservative side. The report calculated that lack of insurance increased mortality rates by 25 percent. But research conducted using more recent data found that not having insurance increases death rates by 40 percent.

In addition, these numbers don’t include children. Children are generally very healthy, and many are eligible for coverage under public programs like the state Children’s Health Insurance Program. But many children aren’t enrolled in Medicaid or other programs for which they’re eligible. According to research cited in the Families USA study, hospital mortality rates were 60 percent higher for children without insurance.

In addition to projecting premature deaths, the new study estimated the number of people who had died since the last major push for health care legislation in the early 1990s. It found that between 1995 and 2009, lack of insurance was responsible for more than 290,000 premature deaths.

Any estimate of this sort depends on the type of health care legislation under discussion. For this report, Families USA relied on Congressional Budget Office estimates regarding the bills that were passed by the House and the Senate, which would increase the number of insured by some 30 million. A health overhaul like the one proposed by Republicans, which would increase the number of insured by about three million, would yield much less bang for the buck.

“Clearly you wouldn’t see the same amelioration of the consequences,” Ms. Stoll said.