States with the most laws regulating firearms, including Massachusetts and New York, have the lowest gun-death rates from homicides and suicides, according to a study published by the American Medical Association.

Physicians and researchers at Boston Children’s Hospital and Harvard University used data on gun fatalities collected by the U.S. Centers for Disease Control and surveys of states’ laws compiled by advocacy groups such as the Brady Center to Prevent Gun Violence to find a statistical relationship between gun regulation and death prevention.

“States that have the most firearm laws have the fewest firearm deaths, and it’s a very direct association,” said Eric Fleegler, lead author of the study published Wednesday in JAMA Internal Medicine. Further studies are needed to draw any conclusions about cause-and-effect relationships, the researchers said.

The article appeared as a debate unfolds in Congress and state legislatures over whether to require more background checks and ban assault weapons and high-capacity magazines in the aftermath of the Newtown massacre. The Dec. 14 shooting inside a Connecticut elementary school left 26 dead, including 20 children, and sparked a national outcry about gun violence.

Louisiana, which has only one gun law, had the highest gun- fatality rate, 18 per 100,000 people, the study showed.

New York averaged 19 firearms laws from 2007 through 2010, the fifth-most among the 50 states. The state had the fourth- lowest gun-death rate, with 4.8 per 100,000, the study found. It trailed Hawaii, Massachusetts and Rhode Island in that category. New York City reported a record-low number of homicides last year. Mayor Michael Bloomberg, who advocates stricter gun control, is the founder and majority owner of Bloomberg News parent Bloomberg LP.

Illinois, whose biggest city, Chicago, has seen a wave of gun violence, ranked ninth in laws and 11th among the states in firearms deaths, with an average 7.9 per 100,000. Chicago recorded 506 homicides last year and drew national attention when a 15-year-old girl, Hadiya Pendleton, who had performed at President Obama’s inauguration, was killed Jan. 29, about a mile from Obama’s South Side home.

Chicago Police Superintendent Garry McCarthy told the Illinois House Judiciary Committee last month that his department “recovers more guns than any municipality in the United States of America, year in and year out.”

A person answering the phone at the Fairfax, Va., press office of the National Rifle Association, the nation’s biggest gun-rights lobby, didn’t immediately respond to a request for comment about the study. The person said it was the organization’s policy not to identify its phone representatives by name.

Hawaii, which ranked sixth among the states with 16 laws, had the lowest rate, 2.9 gun-fatalities per 100,000, the study found. Massachusetts, with the most firearms laws, had a gun- fatality rate of 3.4 per 100,000.

South Dakota was an anomaly. It had only two gun laws, yet its rate of 8.2 gun fatalities per 100,000 ranked below the national median of 9.9, according to the study.

Researchers tallied and scored the states on how many of 24 key gun regulations they had on their books, then split the states into four groups based on the number of laws they had enacted.

When they compared states with the most laws with those that have less than two, rates of homicide and suicide by gun were 42 percent less in states with the most laws, said Fleegler, a pediatrician at Boston Children’s Hospital and professor at Harvard Medical School.

In the four-year period studied, the U.S. experienced 121,084 deaths from guns, averaging more than 30,000 a year.

In 2010 guns were responsible for 68 percent of the 16,259 homicides and 51 percent of the 38,364 suicides, the study reported, citing CDC data. In 2005, the CDC estimated costs from fatal and nonfatal firearm injuries at $711 million in medical care and $40.5 billion in lost work and productivity, the study said.

Newsletter