No exclusive arrangement between a managed care insurer and any person shall require a primary care physician to terminate any existing patient relationship with an individual who is covered by another managed care insurer. The physician shall continue to offer to provide services to existing patients for at least 5 years from the commencement date of this exclusive relationship or the effective date of the change of coverage, whichever is later. During such period, the physician will be reimbursed by the managed care insurer covering the patient at a rate which is not more than the highest rate paid by the insurer for similar services in the same service area.