Cerner Corp. agreed to buy Siemens AG's health information technology unit for $1.3 billion as the U.S. electronic medical records provider plans to tap rising spending on software by hospitals and doctors. The two companies plan a "strategic alliance" around medical devices, imaging and health-care technology, they said yesterday in a statement. The purchase is expected to add more than 15 cents to earnings per share in 2015, Kansas City-based Cerner said. The Obama administration has paid doctors and hospitals about $25 billion to install the systems since 2011, trying to improve the efficiency and safety of health care.