In addition, a growing number of clinics (18-20%) are now run by hospitals or doctor groups, who use or employ their own clinic and administrative personnels or utilize existing supplier centers to serve the worker population. Finally, an increasing number of employers are participating in shared, multi-employer centers, located either on one company's area or centrally located.The supplier will develop, staff and handle the center either at the request of a group of employers or will obtain companies in a specified geographic area. Regardless of the design used, it's key that company stay engaged in supplier selection, center oversight, strategic and policy direction. Staffing practices vary from one onsite center to another, though over 60% of facilities are led by a Nurse Professional or Doctor's Assistant.