In addition, a growing number of centers (18-20%) are now run by hospitals or physician groups, who utilize or employ their own clinic and administrative personnels or make use of existing service provider centers to serve the staff member population. Finally, an increasing variety of companies are participating in shared, multi-employer centers, situated either on one company's location or centrally situated.The vendor will construct, personnel and handle the center either at the request of a group of employers or will get companies in a specified geographic area. No matter the design used, it's essential that employer remain engaged in service provider choice, center oversight, tactical and policy direction. Staffing practices vary from one onsite clinic to another, though over 60% of centers are led by a Nurse Specialist or Physician's Assistant.