Critics opposed to hefty government research spending may think twice after learning that a 15-year, $260 million federally funded study—known as the Women’s Health Initiative (WHI) estrogen plus progestin clinical trial—showed changes in medical practice stemming from the trial provided a net economic return of $37.1 billion over a 10-year period—or about $140 on every federal dollar invested in the trial.

Those findings, published in the Annals of Internal Medicine, are the result of a 15-year trial, a collaboration between WHI and faculty at the Fred Hutchinson Cancer Research Center in Seattle. The lengthy trial, which involved more than 160,000 women nationwide, changed American’s thinking on using combined hormone-replacement  therapy (HRT) as a prevention strategy for cardiovascular disease. Instead, the trial revealed rather than cutting the risk of serious disease HRT did the opposite, increasing the chances women would develop heart disease, blood clots and breast cancer, according to the study results.

“What these findings underscore is the significant role clinical trials play in science and the importance of continuing to find ways to strategically invest public research funds to maximize value to society,” Garnet Anderson, Ph.D., the lead Women’s Health Initiative investigator and director of the Hutchinson’s public health sciences division, said in a statement.

In 2002, the trial was halted after researchers found the associated risks of HRT outweighed the benefits. While 5.5 million women were using HRT, the study’s findings led to a 50% drop in the first year and a continued 5% to 10% drop annually, with the FDA and other groups endorsing the authors’ conclusions.  

To examine what the change in medical practice meant from an economic standpoint, Hutchinson researchers, led by Joshua A. Roth, Ph.D., calculated the financial return as the difference in net economic value between two groups of women—the actual number of women taking HRT after the trial ended and a simulation model of 39 million postmenopausal women who would have taken HRT had there been no trial—minus the $260 million cost of the trial (in 2012 dollars). 

The results and savings show 10 years after the study’s publication, about 4.3 million fewer women were using HRT ($26.2 million), 126,000 fewer breast cancer cases ($4.5 million) and 76,000 fewer cases of cardiovascular disease ($2.2 billion).  The study also pulled together all of the costs of treatments, side effects and loss of life, and subtracted those numbers from the study’s price tag.

The study also revealed HRT therapy may have played a role in preventing colon cancer and bone problems, as the researchers estimated 363,000 more fractures associated with bone weakening and 150,000 more cases of colorectal cancer following the decrease in HRT use.

“It [the study] really brings the point home when you crunch the numbers to see that millions of U.S .women likely stopped or never used combined hormone therapy based on the trial’s findings, and that the change in use resulted in important reductions in disease incidence and associated medical spending,” Roth said in a statement.

The WHI program is funded by the National Heart, Lung and Blood Institute, National Institutes of Health and the HHS.