SEOUL—As North Korea pushes for economic self-reliance, injuries are killing more people every year, according to a new report.

About 15,600 North Koreans a year are dying from injuries, and accidents are overtaxing the regime’s outdated health-care system, which is already under pressure from economic sanctions. The report—by Harvard Medical School and the KF-VUB Korea Chair, which is part of a Brussels-based research institute—says ambulances lack fuel to transport passengers. New parts can’t be ordered for broken medical...