(b) Those costs or charges associated with individual health care providers or health care provider groups providing inpatient or outpatient services under a contractual agreement with hospitals (excluding simple admitting privileges) shall be under the jurisdiction of the board. The jurisdiction of the board shall not extend to the regulation of rates of private health care providers or health care groups providing inpatient or outpatient services under a contractual agreement with hospitals when the provision of such service is outside the hospital setting, and shall not extend to the regulation of rates of all other private health care providers practicing outside the hospital setting: Provided, That such practice outside of the hospital setting is not found to be an evasion of the purposes of this article.