According to a recent international survey,

... only 31% of primary care doctors in the U.S. said they were always notified when a patient was discharged from the hospital, and 32% said they were notified when a patient was seen in the emergency department.
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Source: "New International Survey: One-Quarter of U.S. Primary Care Doctors Say Their Practices Are Not Prepared to Manage Sickest Patients; 84% Not Prepared for Severely Mentally Ill Patients," The Commonwealth Fund/Health Affairs, December 7, 2015, http://www.commonwealthfund.org/publications/press-releases/2015/dec/international-survey-press-release