determined to be under a disability, and is classified as medical improvement possible or medical improvement not expected , the applicable State agency or the Commissioner of Social Security (as may be appropriate) shall, for purposes of determining such individual's continuing disability— (i) if the individual is classified as medical improvement possible , conduct a review to determine whether the individual remains under a disability during the 5th year following the first month after the individual's waiting period (as defined in section 223(c)(2))