In addition, a growing number of centers (18-20%) are now run by healthcare facilities or doctor groups, who use or hire their own clinic and administrative personnels or use existing supplier facilities to serve the employee population. Lastly, an increasing number of companies are taking part in shared, multi-employer centers, situated either on one company's location or centrally located.The vendor will develop, personnel and handle the center either at the demand of a group of companies or will solicit employers in a defined geographic location. Regardless of the model utilized, it's key that company remain participated in service provider 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 Practitioner or Physician's Assistant.