Minnesota's specialty drug courts continue to significantly reduce recidivism and lower incarceration and its related costs for drug court participants, according to a study released Monday by the state's judicial branch.

In 2012, the branch released the first comprehensive evaluation of the effectiveness of the state's drug courts. That study compared 535 drug court ­participants to similar offenders who experienced traditional court processes over 2½ years.

A follow-up to that 2012 evaluation, which tracked the progress of the same drug court participants and similar offenders over an additional year and a half, showed lower recidivism rates and reduced incarceration costs.

"When we first saw the results of our 2012 drug court evaluation, we were thrilled to see the real impact that Minnesota's drug courts were having on some of the most high-risk drug offenders in the state," said Sixth Judicial District Chief Judge Shaun Floerke, co-chairman of the Drug Court Initiative Advisory Committee. "Thanks to this new evaluation, we are now able to see the long-lasting impact drug courts have on the lives of participants, and the real benefits drug courts provide to our communities."

Comparing offenders who spent similar amounts of time outside of incarceration ("at-risk time") during the evaluation period, the new study showed drug-court participants consistently had significantly lower recidivism rates.

For example, among those offenders who reached four years of "at-risk time" during the evaluation, 28 percent of drug court participants had received a new conviction, compared to 41 percent of non-drug court participants.

Drug-court participants spent fewer days incarcerated: Drug-court participants spent, on average, 74 fewer days incarcerated in jail or prison compared to similar offenders during the four-year evaluation period. The average cost savings for each drug court participant was $4,288 as a result of the reduced ­incarceration.

Minnesota has 50 drug courts in operation.