States that require prescribers and dispensers to register with and use prescription drug monitoring programs saw notably fewer opioid prescriptions and reduced opioid-related hospital use compared to states with weak drug monitoring program mandates, according to a new study from investigators at Weill Cornell Medicine. The approximate annual reduction of about 12,000 inpatient stays and 39,000 emergency department visits could save an estimated $155 million a year in Medicaid spending.