A new study by Cornell University says research over the past 25 years points to a wide consensus that transgender medical treatment is effective, despite a Pentagon determination that the science remains uncertain.

The university looked at 56 peer-reviewed studies on how hormone treatment or surgery can help transgender people. Ninety-three percent reported the treatment improved their well-being, according to a summary provided by Cornell.

The findings represent a “robust international consensus” on treatment, the university said.

“Among researchers who have studied gender transition, there is little doubt that it improves the well-being of transgender people, often markedly,” said Nathaniel Frank, the director of Cornell’s What We Know Project for policy and co-author of the study. “A consensus like this is rare in social science.”

Defense Secretary Jim Mattis is seeking to bar anybody who has had hormone therapy or surgery treatment from enlisting in the military, and to deny treatment to those who are already serving.

The new policy recommendations were unveiled last month as part of a 44-page review of the issue of transgender military service and the existing outside research on the subject. It remains on hold for now as the Trump administration battles transgender troops and rights groups in federal court over the changes.

In a key finding, Mattis determined transgender people diagnosed with gender dysphoria, a condition of being unhappy or anxious about their current gender, had higher levels of mental health issues such as suicide. The study also said there was no proof that treatment could solve those issues.

“While there are numerous studies of varying quality showing that this treatment can improve health outcomes for individuals with gender dysphoria, the available scientific evidence on the extent to which such treatments fully remedy all of the issues associated with gender dysphoria is unclear,” the Pentagon review says.

Three major medical associations have also questioned the conclusion and called Mattis’ proposed transgender policy discriminatory.

The Pentagon and White House have “mischaracterized and rejected the wide body of peer-reviewed research on the effectiveness of transgender medical care,” James Madara, CEO of the American Medical Association, wrote in a letter to Mattis last week. “We believe there is no medically valid reason — including a diagnosis of gender dysphoria — to exclude transgender individuals from military service.”

The American Psychiatric Association and American Psychological Association have issued statements opposing the policy and told the Washington Examiner they believe the Pentagon is misrepresenting the current medical consensus.