The well-known program that seeks to help people with alcohol use disorder, Alcoholics Anonymous, has long been criticized for not having the medical research to back up its efficacy.

Until now.

A new study published by the medical journal Cochrane Database of Systematic Review found the peer-led program not only helps people get sober, but it also has higher rates of continuous sobriety compared with professional mental health therapy, such as cognitive behavioral therapy.

The study is important because it dispels misinformation about the program, said lead author Dr. John Kelly, a professor of psychiatry and addiction medicine at Harvard Medical School.

“In the popular press, there’s been reports of AA not working or being even harmful for people,” he said. “So, we wanted to clarify the scientific picture to the highest scientific standard.”

The study had the opposite findings of a similar study published by Cochrane in 2006 that found “no experimental studies unequivocally demonstrated the effectiveness of AA or TSF (twelve-step facilitation) approaches for reducing alcohol dependence of problems."

The 2006 review included eight trials with about 3,400 people, while the new review included 27 studies of more than 10,500 people.

The studies reviewed for Wednesday's publication rated AA's effectiveness by measuring factors including the length of time participants abstained from alcohol, the amount they reduced their drinking, if they continued drinking, the consequences of their drinking and their health care costs.

AA was never found less effective and was often significantly better than other interventions or quitting cold turkey. One study found the program 60% more effective than alternatives.

Lisa Smith, a recovery advocate who chronicled her addiction and recovery from alcoholism and cocaine in the book "Girl Walks Out of a Bar," said the study "provides important confirmation to what I have seen throughout my 15 years of sobriety in AA."

“Anyone struggling with their drinking can walk into a meeting full of people who’ve been there and are ready offer support," said Smith, an attorney.

Psychologist Keith Humphreys, co-author of the study and a Stanford University psychiatry professor, said mental health professionals – including him early in his career – are frequently skeptical of AA's effectiveness. Psychologists and psychiatrists are often trained to provide cognitive behavioral therapy and motivational enhancement therapy to treat patients with alcohol-use disorder.

He recalled thinking, “How dare these people do things that I have all these degrees to do?”

Kelly said the peer-led basis of AA is what makes the program so effective and has the potential to save health care providers $10 billion a year in alcohol-related incidents. The program is free.

Women and the bottle. Alcohol is killing more people, and younger.

They were young. They thought they had time. Then they nearly died of liver disease.

'Deaths of despair':Drugs, alcohol and suicide hit young adults hardest

“AA didn’t come from the scientific community, it came from people who were suffering addiction,” he said. “They’re just people with lived experience, and that’s powerful when you multiply that by a couple of million people.”

The study found higher rates in long-term sobriety when medical professionals connected their patients to AA after completing a 12-step program. Kelly hopes that the review will encourage more studies of other programs, possibly without spiritual elements, such as Smart Recovery.

It is the spiritual aspect of AA that turns people off and sends them to alternatives, said Smart Recovery executive director Mark Ruth. AA and other 12-step programs recommend the use of a higher power to help members recognize something, even if it isn't God or any religious deity, has a power greater than they are.

"We believe in faith as part of a person’s personal choice, not as part of a program or a tool," he said.

Meeting facilitators are trained to "redirect conversations" when faith comes up as the program wants to remain science and evidence based, he said.

Although the federal Substance Abuse and Mental Health Administration recommends the use of "medication-assisted treatment" combined with therapy for opioid addiction, many in 12-step programs including AA don't consider people taking these anti-craving drugs to be sober. Ruth says that's another key differentiator for his program, which has "no stigmas" and focuses on "where they want to go and how we can assist them to get there."

According to the 2018 National Survey on Drug Use and Health, 14.4 million adults over 18 have alcohol use disorder.

An estimated 88,000 people die from alcohol-related causes annually, making alcohol the third leading preventable cause of death in the U.S. behind tobacco and poor diet, according to the National Institute on Alcohol Abuse and Alcoholism.

Smith, Ruth and the study authors said it's most important for people to find an approach to recovery that works.

"As an organization, we have nothing but great respect for the AA 12-step program," said Ruth. "It's like choosing a vanilla shake versus a chocolate shake."

Follow Adrianna Rodriguez on Twitter: @AdriannaUSAT.

If you're struggling with issues mentioned in this story and you would like to connect with others online, join USA TODAY’s "I Survived It" Facebook support group.