; or (III) whether the individual meets other criteria as determined appropriate by the Secretary. (iv) If the prior authorization request is approved, such request shall be retroactive to the date on which such request was received. (v) An approved prior authorization shall be valid for a 60-day period. The Secretary may provide for an extension of such period if the Secretary determines such an extension is appropriate. (vi) An approved prior authorization shall be deemed to constitute medical necessity but shall not eliminate the documentation requirements necessary to support a claim for the transport. (vii) Other elements determined appropriate by the Secretary. (C) Reliance upon contractors The Secretary may rely upon contractors to implement the requirements of this paragraph. The contractor’s compensation shall be limited to a demonstration that it has reduced the number of non-emergency basic life support services involving individuals with end-stage renal disease for renal dialysis services (as described in section 1881(b)(14)(B)) furnished other than on an emergency basis. (D) Applicable ESRD ambulance services In this paragraph, the term applicable ESRD ambulance services means ambulance services consisting of non-emergency basic life support services involving transport of an individual with end-stage renal disease for renal dialysis services (as described in section 1881(b)(14)(B)) furnished other than on an emergency basis. (E) Ambulance service provider In this paragraph, the term ambulance service provider means an entity that furnishes ambulance services (as described in section 1861(s)(7)) and is not a provider of services (as defined section 1861(u)). (F) Implementation (i) In general Subject to clause (ii), the Secretary may carry out this paragraph through program instruction or otherwise. (ii) Sufficient notice to prepare Not later than June 30, 2018, the Secretary shall make the aspects of the process under this paragraph available to the public. . (b) References to ambulance service