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 staffs or use existing company centers to serve the employee population. Lastly, an increasing number of companies are taking part in shared, multi-employer clinics, located either on one employer's area or centrally located.The supplier will build, staff and manage the center either at the request of a group of companies or will get employers in a specified geographic area. No matter the design used, it's key that company stay engaged in provider choice, center oversight, strategic and policy direction. Staffing practices vary from one onsite clinic to another, though over 60% of centers are led by a Nurse Practitioner or Doctor's Assistant.