Expanding health insurance coverage in Massachusetts helped reduce deaths, a Harvard University study found, suggesting that Obamacare may help save lives as it’s rolled out nationwide.

Massachusetts enacted comprehensive health coverage in 2006, serving as a model for the 2010 Patient Protection and Affordable Care Act known as Obamacare. The state reported about 3 percent fewer deaths in the four years after the overhaul than previously, according to researchers from the Harvard University School of Public Health. The study published in the Annals of Internal Medicine found no similar decline in death rates in other states that hadn’t enacted health reform.

The findings showed that increasing health insurance coverage helped saves lives from illnesses that can get better with timely medical care such as cancer, infections and heart disease, said Benjamin Sommers, a lead study author. The decline in mortality was largest in Massachusetts counties with lower incomes and higher uninsured rates before the changes.

“Our results suggest that health insurance matters a lot for people’s lives,” Sommers, an assistant professor of health policy and economics at Harvard University School of Public Health in Boston, said in a telephone interview. “It makes it easier for them to get the care they need, they feel better about their health and they live longer. The evidence is mounting that giving people health insurance who didn’t have it before makes a major difference in their lives.”

Future studies need to look at whether there are similar declines in deaths in the U.S. from the Affordable Care Act, he said. Eight million people signed up for private health plans under the program, the U.S. government said.

The study released yesterday “adds big weight to the side that, yes, expanding health insurance coverage does improve health,” David Auerbach, a policy researcher at RAND Corp. in Boston, in a telephone interview. Auerbach wasn’t involved in the study.

Researchers looked at mortality changes for adults 20 to 64 years old in Massachusetts prior to the health overhaul, the period from 2001 to 2005, and after, the years 2007 to 2010. They also compared the changes in Massachusetts with similar counties in states that hadn’t passed health care changes.

They found the Massachusetts health law prevented about 320 deaths a year, or one life saved for every 830 people who gained insurance. That meant that the each person who gained health insurance lowered their risk of dying by about 30 percent, the authors said.

The drop in mortality was about twice as large for nonwhites and Latinos as it was for whites, the findings showed.

Kavita Patel, a fellow at the Brookings Institution in Washington, said Massachusetts had a lower rate of uninsured people to start with than other states.

“In other states, I would predict we would see even stronger findings,” Patel, who didn’t participate in the research, said in a telephone interview. “Access matters. That’s the bottom line.”

Separately, Massachusetts officials said yesterday they are trying to fix the state’s health insurance exchange created under Obamacare or may join the U.S. enrollment system on a temporary basis. Technical flaws prevented the state from signing up customers online after its exchange was introduced last October.