In determining, for initial entitlement to benefits, whether an individual is disabled,
we follow a sequential evaluation process whereby current work activity, severity
and duration of impairment, ability to do past work, and ability to do other work
(in light of the individual's age, education and work experience) are considered,
in that order. In determining continuing entitlement to benefits, the adjudicator,
with appropriate consideration of the medical improvement review standard, also follows
a sequential evaluation process which includes the “not severe impairment” concept. Fundamental to these processes is the statutory requirement that to be found
disabled, an individual must be unable to engage in “any substantial gainful activity by reason of any medically determinable physical or mental impairment...” (emphasis added). In reporting on the Social Security Amendments of 1954 which first
introduced this basic definition of disability into the Act, the Senate Committee
on Finance stated that the definition required that there be a “medically determinable impairment of serious proportions ,” that is, “of a nature and degree of severity sufficient to justify its consideration as the
cause of failure to obtain any substantial gainful work.”