For some people with severe mental illness, life is a cycle of hospitalization, skipped medication, decline and then rehospitalization. They may deny they have psychiatric disorders, refuse treatment and cascade into out-of-control behavior that can be threatening to themselves or others.

Now, a study has found that a controversial program that orders these patients to receive treatment when they are not hospitalized has had positive results. Patients were much less likely to end up back in psychiatric hospitals and were arrested less often. Use of outpatient treatment significantly increased, as did refills of medication. Costs to the mental health system and Medicaid of caring for these patients dropped by half or more.

The study evaluated the program run by New York State, known as Kendra’s Law because it was enacted after Kendra Webdale was pushed to her death on the New York City subway tracks by a man with untreated schizophrenia in 1999. Forty-four other states have some form of Kendra’s Law, but New York’s is by far the most developed because the state has invested significant resources into paying for it, experts say.

From the start, Kendra’s Law has had staunch defenders and detractors. But the new analysis, led by researchers at Duke University and published in The American Journal of Psychiatry, joins a series of studies that suggest the program can be helpful for patients who, while they constitute only a small number of the people with mental illness, are some of the most difficult and expensive to care for.