Example: The annuitant was previously found to be disabled on the basis that while his impairment was not medically disabling, it did prevent him from doing his past or any other work. The prior adjudicator did not, however, include a residual functional capacity assessment in the rationale of that decision and a review of the prior evidence does not show that such an assessment was ever made. If a decrease in medical severity, i.e., medical improvement, has occurred, the residual functional capacity based on the current level of severity of the annuitant's impairment will have to be compared with his residual functional capacity based on its prior severity in order to determine if the medical improvement is related to his ability to do work. In order to make this comparison, the Board will review the prior evidence and make an objective assessment of the annuitant's residual functional capacity at the time of its most recent favorable medical determination, based on the symptoms, signs and laboratory findings as they then existed.
20 C.F.R. §220.178