Not having health insurance could put your life at risk. Or it might not make any difference at all.

A new study has calculated that more than 26,000 Americans died prematurely in 2010 as a direct result of not having health insurance. The study, published on Wednesday by health care advocacy group Families USA, has raised old questions about whether health insurance coverage has any bearing on a person's odds of living longer.

Families USA's key finding -- 26,100 premature deaths a year for those 25 to 64 -- is a figure most would find sobering. This works out to about one death every 20 minutes. But it's a conclusion that some researchers might have difficulty accepting, since its methodology is similar to that used in an earlier report with a troubled history.

What is certain is that the Families USA report arrives at a loaded moment, with the Supreme Court preparing to issue a judgment on the constitutionality of the Affordable Care Act, the 2010 health care overhaul designed to provide coverage to some 30 million Americans who lack it.

Ron Pollack, executive director of Families USA, said the availability of care is "not a trivial matter" for the roughly 50 million Americans without health insurance.

"When people are uninsured, what they often do is defer care," Pollack told reporters on a Wednesday conference call. "Some people pay the ultimate price when they don't get that care or don't get it in a timely manner."

The Supreme Court is expected to rule on the Affordable Care Act by June 28.

Pollack told reporters that he and his organization "have great confidence" in the study's conclusions, which indicate that the premature mortality rate among the uninsured grew slightly higher almost every year from 2005 to 2010.

Yet those findings are based on a methodology used in another study from a decade ago that has met with some skepticism in the research community.

The earlier study, published in 2002 by the Institute of Medicine, claimed to find that 18,000 Americans had died in 2000 as a result of having no health insurance.

The findings were widely repeated and even amplified in 2008, when Stan Dorn, a research associate at the Urban Institute, published follow-up research claiming that by 2006 the number of Americans dying as a result of not having insurance had climbed to 22,000 a year.

But there were also dissenting voices. Richard Kronick, then a professor in the Department of Family and Preventive Medicine at the University of California, San Diego School of Medicine, argued in a 2009 paper that the Institute of Medicine report had failed to correct for certain health-related variables, like smoking and body mass index.

Kronick argued that when these and other health factors were taken into account, no significant difference could be found between people who have insurance and those who don't.

"The answer suggested by the evidence presented here is that there would not be much change in the number of deaths in the U.S. as a result of universal coverage," he wrote -- an assertion that a number of policy analysts, of various ideological stripes, said they agreed with, according to the Tampa Bay Times' PolitiFact.

During the call on Wednesday, Pollack defended Families USA's use of the Institute of Medicine methodology.

The institute is "probably as prestigious and highly respected as any scientific body," said Pollack in response to a question from The Huffington Post. If anything, "most of the criticism" of the 2002 study has accused the institute's researchers of being "conservative" rather than inflating the data, he said.

Later, Kim Bailey, research director at Families USA and lead author of the new report, told HuffPost that while "there are always studies that contradict each other," the organization considered the Institute of Medicine research to be an "incredibly rigorous" treatment of available data.

"They're not actually doing original research of their own -- what they're doing is aggregating the research that exists," said Bailey about the institute. But "a huge prevalence of data" shows "an overwhelmingly strong link between uninsurance and premature mortality," she said.

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