A new study finds requiring doctors to register with their state prescription drug monitoring program reduces the amount of opioid painkillers Medicaid patients receive. The program uses a database to track patients’ opioid prescriptions. The study also found requiring doctors to register with the program saved money, Philly.com reports. Requiring doctors to register with their state program led to an almost 10 percent drop in prescriptions for the most potent opioids between 2011 and 2014, researcher report in Health Affairs. The study found mandatory checking of the database was no more effective than requiring providers to register. The prescription drug monitoring programs are designed to reduce the number of patients who “doctor-shop,” or get prescriptions from multiple doctors.